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FLOOD DAMAGED

property

David Proverbs & Robby Soetanto

Flood Damaged Property A Guide to Repair

Flood Damaged Property A Guide to Repair David G. Proverbs School of Engineering and the Built Environment, University of Wolverhampton and

Robby Soetanto Department of Civil and Building Engineering, Loughborough University

ß 2004 by Blackwell Publishing Ltd Editorial offices: Blackwell Publishing Ltd, 9600 Garsington Road, Oxford OX4 2DQ, UK Tel: þ44 (0)1865 776868 Blackwell Publishing Inc., 350 Main Street, Malden, MA 02148-5020, USA Tel: þ1 781 388 8250 Blackwell Publishing Asia Pty Ltd, 550 Swanston Street, Carlton, Victoria 3053, Australia Tel: þ61 (0)3 8359 1011 The right of the Author to be identified as the Author of this Work has been asserted in accordance with the Copyright, Designs and Patents Act 1988. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. First published 2004 by Blackwell Publishing Ltd Library of Congress Cataloging-in-Publication Data Proverbs, David G. Flood damaged property: a guide to repair / David G. Proverbs and Robby Soetanto. p. cm. Includes bibliographical references and index. ISBN 1-4051-1616-1 1. Flood damage–Risk assessment. I. Soetanto, Robby. II. Title. TC530.P77 2004 690’.24–dc22 2004001821 ISBN 1-4051-1616-1 A catalogue record for this title is available from the British Library Set in 10/13pt Palatino by Kolam Information Services Pvt. Ltd, Pondicherry, India Printed and bound in India by Gopsons Papers Ltd, Noida The publisher’s policy is to use permanent paper from mills that operate a sustainable forestry policy, and which has been manufactured from pulp processed using acid-free and elementary chlorine-free practices. Furthermore, the publisher ensures that the text paper and cover board used have met acceptable environmental accreditation standards. For further information on Blackwell Publishing, visit our website: www.blackwellpublishing.com

Contents Preface Acknowledgements 1

2

Introduction to Flooding

1

1.1 1.2 1.3 1.4 1.5 1.6

1 1 2 3 4 7

Introduction Flood risk Causes and effects of flooding Flood protection Flood resilient repairs Summary

9 9 9 12 13 14 15

Flood Characteristics

16

3.1 3.2 3.3 3.4

16 16 20

3.5 4

Introduction Autumn 2000 floods Ownership and responsibilities Damage caused by flooding Flood damage to domestic properties Organisation of this book

Preparing for a Flood 2.1 2.2 2.3 2.4 2.5 2.6

3

ix xi

Introduction Flood damage function The importance of flood characteristics Sources of information or methods to determine flood characteristics Summary

22 26

Drying Out Flooded Buildings

27

4.1 4.2 4.3

27 27

4.4 4.5 4.6

Introduction Background information Methods and/or equipment employed to dry flood damaged buildings Sealing off sections of the building to assist drying Methods and/or equipment employed to determine if a building is sufficiently dry for repair works to commence Summary

30 34 35 38 v

vi

5

Contents

Reinstatement of Flood Damaged Floors

40

5.1 5.2 5.3

40 41 42

5.4 6

Introduction Methodology Results and discussion 5.3.1 Scenario 1: ‘The dwelling has vinyl floor tiles installed that have been submerged by floodwater’ 5.3.2 Scenario 2: ‘The dwelling has a vinyl sheet floor covering installed that has been submerged by floodwater’ 5.3.3 Scenario 3: ‘The dwelling has a quarry tiled floor which has been submerged by floodwater’ 5.3.4 Scenario 4: ‘The dwelling has a solid concrete floor which has been submerged by floodwater’ 5.3.5 Scenario 5: ‘The dwelling has a suspended timber (chipboard) floor which has been submerged by floodwater’ 5.3.6 Scenario 6: ‘The dwelling has a suspended timber (chipboard) floor with tongued and grooved floorboards’ 5.3.7 Scenario 7: ‘When the floorboards are removed, it is discovered that the sleeper walls are constructed directly off the ground (i.e. no concrete slab has been included)’ 5.3.8 Scenario 8: ‘The dwelling has a concrete floor which has been covered with solid oak blocks’ Summary

43

45 48 52

55

58

61 65 70

Reinstatement of Flood Damaged Walls

78

6.1 6.2

78 78

Introduction Results and discussion 6.2.1 Scenario 9: ‘The external wall of the property is brickwork with cement mortal joints’ 6.2.2 Scenario 10: ‘The external wall of the property has a rendered finish’ 6.2.3 Scenario 11: ‘The external wall of the property has a pebbledash finish’ 6.2.4 Scenario 12: ‘An internal wall of the flood damaged property is constructed of brickwork with a paint finish applied directly to it’ 6.2.5 Scenario 13: ‘An internal wall of the flood damaged property has been covered with ceramic tiles’

78 81 85

89 91

Contents

6.2.6

6.3 7

Scenario 14: ‘An internal wall of the flood damaged property has been covered with a wood veneer on timber grounds’ 6.2.7 Scenario 15: ‘An internal wall of the flood damaged property has been decorated with wallpaper’ 6.2.8 Scenario 16: ‘An external wall of a flood damaged property has evidence of a rising damp problem’ 6.2.9 Scenario 17: ‘Following removal of the wall’s plaster, it is found that the wall has been incorrectly constructed’ 6.2.10 Scenario 18: ‘Floodwater has been in contact with an internal block wall which has a gypsum plaster finish’ 6.2.11 Scenario 19: ‘Floodwater has been in contact with an internal block wall which has a cement/sand mix undercoat and a 1 mm plaster skim applied to it’ 6.2.12 Scenario 20: ‘Floodwater has been in contact with an internal brick wall which is finished with a lime/ ox-hair mix and a lime putty finish’ 6.2.13 Scenario 21: ‘Floodwater has been in contact with an internal timber partition wall’ 6.2.14 Scenario 22: ‘Floodwater has been in contact with an internal metal-framed partition wall’ Summary

vii

94 97 99

102

105

109

111 114 118 121

Reinstatement of Flood Damaged Doors and Windows

132

7.1 7.2

132 132

7.3

Introduction Results and discussion 7.2.1 Scenario 23: ‘A flood damaged property has a softwood front door that has been in contact with floodwater’ 7.2.2 Scenario 24: ‘A flood damaged property has double glazed hardwood patio doors that have been in contact with floodwater’ 7.2.3 Scenario 25: ‘A flood damaged property has hollow cellular type infill wooden doors that have been in contact with floodwater’ 7.2.4 Scenario 26: ‘A flood damaged property has a PVC external door that has been in contact with floodwater’ 7.2.5 Scenario 27: ‘A flood damaged property has wooden window frames that have been in contact with floodwater’ Summary

132

135

138 141 144 147

viii

8

Contents

Reinstatement of Flood Damaged Utilities and Fittings

152

8.1 8.2

152 152

8.3 9

Introduction Results and discussion 8.2.1 Scenario 28: ‘A flood damaged property has steel panel radiators installed that have been in contact with floodwater’ 8.2.2 Scenario 29: ‘A flood damaged property has a gas fired heater that has been in contact with floodwater’ 8.2.3 Scenario 30: ‘A flood damaged property has a gas meter that has been in contact with floodwater’ 8.2.4 Scenario 31: ‘A flood damaged property has a wall-hung gas fire that has been in contact with floodwater’ 8.2.5 Scenario 32: ‘The dwelling has an electrical circuit containing sockets and cables which have been partly submerged by floodwater’ 8.2.6 Scenario 33: ‘The dwelling has a wall-hung electrical heater that has been submerged by floodwater’ 8.2.7 Scenario 34: ‘The dwelling has timber skirting boards’ 8.2.8 Scenario 35: ‘The dwelling has a staircase constructed from timber’ 8.2.9 Scenario 36: ‘The dwelling has built-in wall cupboards’ 8.2.10 Scenario 37: ‘The dwelling has a ‘‘fitted’’ kitchen that has been partially submerged above the plinths by floodwater’ Summary

152 156 159

162

165 169 172 175 178

182 185

Conclusions and Summary

194

9.1 9.2 9.3 9.4 9.5

194 194 195 196 201

Introduction Flood characteristics Drying out flooded buildings Reinstatement of flood damaged domestic properties Recommendations

Appendix A: Data Collection and Characteristics of the Survey Respondents Appendix B: Useful Sources of Information References Bibliography Index

204 212 213 216 221

Preface The inspiration for this book came about from discussions with Ian Jones (Technical Claims Manager, Lloyds TSB Insurance) and Brian Garbett (Director, Rameses Associates Ltd). Both Ian and Brian are involved in the repair of flood damaged property (as insurer and damage specialist contractor, respectively) on a daily basis. They identified that, prior to the publication of this book, there was no definitive guidance available to professionals involved in reinstating flood damaged property to its pre-incident condition (a fact confirmed in the subsequent detailed literature review conducted before the benchmarking exercise) and, as such, there is considerable variance in the quality and scope of repair services offered by the insurance sector. The situation is best demonstrated using a scenario. Imagine the situation where a serious flood event was to affect two nearly identical properties (for example, two terraced houses situated side by side) involving two different insurers. Here, the characteristics of the flood and the characteristics of the property are much the same and as such, in an ideal world, the extent of their restoration and repairs should be much the same. However, without any definitive guidance, the experts involved (loss adjusters, insurers, surveyors, damage specialists, etc.) would tend to rely on their experience in determining the precise scope and quality of repairs to be carried out. In this situation, it is possible that the properties would be repaired to different standards, leading to complaints from the homeowners on discovery that (for example) their neighbours had had their carpets replaced, while their own had just been cleaned. The main contribution of this book, therefore, is to provide guidance where before there was none. The book will be of interest to all parties involved in the repair of flood damaged properties. For insurers, the book provides the first published benchmark standards for the technical repair of property, allowing the clear determination of standards required from their contractors and subcontractors involved in the reinstatement supply chain. Equally, practising loss adjusters, loss assessors, building surveyors and specialist damage management companies and drying firms will find the book a reliable source of information in determining the scope and quality of repair works. Property owners and particularly homeowners will find the contents provide a useful reference point in assessing the quality of service offered by their insurance company in the aftermath of a flood. However, readers should not interpret these benchmarks as ultimate solutions, as conditions such as environmental factors may vary from one property to another. Nevertheless, these benchmarks represent the first attempt to standardise the reinstatement of flood ix

x

Preface

damaged domestic properties and, if adopted throughout the industry, should lead to a more effective damage management service. The visual images of the various building elements used in the book are taken from real-life flood damaged properties and were not taken for the purposes of publication. As such the quality is not of the normal standards required for book publishing. The authors did consider the possibility of sourcing better quality images, but instead decided to proceed with those used in the data gathering process so as not to introduce any bias or in any way misrepresent the information on which the benchmarks have been developed.

Acknowledgements The authors would like to express their sincere appreciation to several individuals who have contributed towards this publication in a variety of ways. We are especially grateful to Ian Jones and his employer, Lloyds TSB Insurance, for funding the benchmarking research project which forms a major part of the book, and also for funding the development of the book manuscript. Furthermore, Ian and Brian Garbett of Rameses Associates Ltd played a significant role throughout the duration of the research project for which we are truly appreciative. Thanks are also extended to John Nicholas who led the development of the research instrument and to Gary Holt who helped secure the funding for the original research. Stephen Brown of the RICS Research Foundation also kindly provided assistance in identifying suitably qualified chartered surveyors to participate in the research. We are also indebted to the numerous flood property experts who completed the research instrument and provided the data on which the benchmarks are based. We would also like to extend our thanks to the following for kind permission to reproduce various images, figures and tables that form part of the book: .

. .

Dr Ilan Kelman of CURBE, University of Cambridge, the Institution of Civil Engineers and North Wales Newspapers for the images used on the front cover. The Chartered Institute of Building and Elsevier Science for Figure 4.1 and Table 4.1, respectively. Rameses Associates Ltd for the flood images.

Finally, our many thanks to Julia Burden and the staff at Blackwell Publishing Limited for helping to bring this book to fruition.

xi

1 1.1

Introduction to Flooding Introduction Floods often cause considerable damage to properties, demanding huge financial sums for repair works, the temporary closure of businesses and the uprooting of families from homes. Recent catastrophic flooding in parts of the UK and elsewhere in Europe has highlighted the need for urgent action to address future flood risks and develop appropriate engineering solutions. It is estimated that some two million homes and 185 000 business properties are at risk from flooding in England and Wales alone. With a financial value of over £222 billion, it is clear why flooding has become a priority for the government. Among natural disasters, floods are the most destructive in terms of magnitude and human impact. In the UK, the worst recorded coastal flooding in 1953 claimed 480 lives and cost an estimated £5 billion worth (at current prices) of damage. Crichton (2003) argued that a similar flood today could lead to more deaths and insured losses of over £20 billion. The situation is further magnified due to climate changes that are occurring on a world-wide scale, with generally wetter winter periods and significant increases in coastal water levels. In short, the frequency of flooding is set to increase, with many previously unaffected properties now at risk due to changes in weather patterns and from poorly controlled property development in flood plain areas.

1.2

Autumn 2000 floods September 2000 through to March 2001 was the wettest period ever recorded in the UK. A series of storms crossed England during the autumn, followed by high rainfall throughout the winter into early spring. In November 2000, the equivalent of two months’ rain fell on the Yorkshire Dales in 10 days. As a historical comparison, the total rainfall from autumn to spring 2000–2001 was some 10% higher than the previous highest recorded in 1935. Compared to the average monthly rainfall, some sites experienced in excess of twice the average amount for two or three months in succession. Each of the specific rainfall events caused widespread disruption as surface water overwhelmed land and highway drainage systems, and watercourses inundated flood plains. Many properties were affected and, in some cases, were flooded more than once. Additionally, as winter rains continued, 1

2

Chapter 1

groundwater levels became very high, resulting in a number of villages being flooded directly from this somewhat unexpected source. Over 10 000 homes and businesses were flooded, causing damage to property and severe distress to thousands of people across the country. The Association of British Insurers (ABI) estimated costs for the repair and reinstatement of property, including contents, to be over £800 million. The Environment Agency reported the cause of these floods to be as follows: . . . . .

1.3

40% had no flood defences; 26% involved the overtopping of defences; 18% were due to main river flooding; 14% were due to inadequate land drainage; and 2% involved the outflanking of defences.

Ownership and responsibilities The Department of Environment, Food and Rural Affairs (DEFRA) has policy responsibility for flood and coastal defence in England, while operational responsibility for delivering the service falls to the ‘operating authorities’, namely the Environment Agency and local authorities. The Environment Agency has a general supervisory duty over all matters relating to flood defence and also responsibility for flood forecasting and flood warning arrangements. Watercourses are divided into ‘Main River’ and ‘ordinary watercourses’ (all other watercourses). Main Rivers are generally the arterial watercourses and are designated by DEFRA. The power to consent to work being carried out on Main Rivers is held by the Environment Agency and for ordinary watercourses by the local authorities. It should be noted that a watercourse is a conduit through which water may flow, and there are both Main Rivers and ordinary watercourses that are ephemeral (water only flows on occasion). Ordinary watercourses are classified as ‘Critical Ordinary Watercourses’ where a lack of appropriate maintenance could cause significant risk of flooding, and these receive a higher standard of inspection.

1.3.1 The Environment Agency The Environment Agency has responsibility to maintain and improve ‘Main Rivers’ and to construct and maintain sea defences to prevent flooding from the sea. The Agency also has powers to regulate works by others close to Main Rivers and sea defences. The Agency operates a flood warning service for river and coastal flooding, where it is technically feasible to do so, and

Introduction to Flooding

3

disseminates warnings to other organisations and directly to the public. The two main duties of the Agency are to: . .

exercise a general supervision over all matters relating to Flood Defence; and carry out surveys of areas where it carries out flood defence works.

1.3.2 Other authorities District, borough and unitary authorities have permissive powers similar to those of the Environment Agency to maintain and improve watercourses and, in some cases, powers to require landowners to carry out maintenance works. County and unitary authorities have two distinct interests in land drainage matters, namely as a drainage authority and as a highways authority. The county authority has similar district controls as a drainage body but, in general, may only act at the request, or in default of, the district council. The Highways Authority has a responsibility to keep roads free from flooding and make provision for run-off from highways. The water companies are responsible for the foul sewerage system and the surface water sewerage system if it has been adopted. They do not have responsibilities for any other watercourses or land drainage systems. The owner of land adjacent to a watercourse is known as a riparian owner and has rights and duties. In general, riparian owners are expected to maintain the watercourse and to accept flow from any upstream neighbours and pass this on to downstream owners. There is no liability to improve a natural watercourse. Parish and town councils are not ‘drainage bodies’ under the legislation and so do not have specific land drainage powers. They do, however, have general powers to assist in their neighbourhood and can be of great assistance to the other authorities in providing a link to the communities.

1.4

Damage caused by flooding The damage caused by floods can be categorised into two generic groups, namely direct damage and indirect damage. Direct damage is the physical damage caused to buildings and their contents, whereas indirect damage represents the loss of industrial or business process. In addition to these groups, losses due to flooding can also be classified as being tangible and intangible losses. Tangible losses represent those that can be allocated a monetary value (e.g. costs of repair works), and intangible losses are those to which it is impossible to allocate a monetary value (e.g. psychological damage, such as distress caused to property owners).

4

Chapter 1

The ABI has reported that half a metre of floodwater in a modern semidetached house results in an average cost of £15 000–30 000 for repair works to the building and £9000 for the replacement of damaged belongings. Of course, when a flood occurs, the psychological damage caused to the building’s occupier(s) or owners can be equally as devastating as the physical damage. However, these psychological issues are considered to be beyond the scope of this book. The main characteristics of the flood that influence the extent of damage caused to a property are flood depth, duration and contaminants. Flood depth The depth of floodwater is clearly a key issue in determining the scale of damage. Once levels rise above the ground floor, then damage increases significantly when internal fittings and components become affected. Flood depths greater than 1 metre above floor level are likely to result in structural damage to buildings. Duration Generally, the longer the floodwater remains in contact with buildings, the more extensive is the damage caused. Most construction materials are porous (e.g. bricks, blocks and plaster) and will soak up floodwater until they become saturated. This may render materials beyond repair or at least extend the time needed to dry them out. Contaminants Floodwater can be contaminated with, for example, sewage from blocked drains and chemicals from garages or commercial properties. Often, after the floodwater has receded, a layer of contaminated silt is left behind. Contamination can add to the cost of cleaning and disinfecting buildings, and brings with it some risks to health for both property owners and for those involved in repair and reinstatement works.

1.5

Flood damage to domestic properties When considering flood damage to domestic properties, the physical and geographical position of the dwelling(s) has to be considered. This is because different physical locations are prone to different probabilities of flooding and different types of floodwater. Factors influencing a location’s probability of flooding are as follows:

Introduction to Flooding

. . . .

5

distance from source of flood or potential flood (river, stream, dam, sewer, etc.); height of ground, above or below flood source, on which the dwelling is built; any physical mitigation measures that are installed (dams, flood walls, etc.); and planned mitigation measures upon receiving a flood warning.

A conscious decision has to be made by potential purchasers of properties built on flood plains. This decision revolves around whether the risk of flooding occurring and the damage that a flood will cause is significant when compared to the ‘benefits’ that the property offers the purchaser. Purchasers of property in flood plain areas should seek cover against the potential damage of a flood event as part of their household insurance policy. In effect, the purchasers have to reach a compromise between having a property with the characteristics that it offers and paying the higher insurance premium that will be demanded to cover the ‘higher’ flood risk.

1.5.1 Impact on property value and insurance A recent flood event may adversely affect the value of a residential property, depending on the local property market and the particular property in question. Research has shown that this may typically involve a discounted value of some 12%, but depends very much on the individual circumstances of the property (Wordsworth et al., 2003). The availability of and the terms and conditions attached to buildings insurance cover are key issues in determining the saleability and value of a property, since such insurance cover is usually a prerequisite of mortgage lending on the property. The insurance and mortgage sectors have, in general, responded positively to the increased risk of flooding. First and foremost, insurers agreed to continue to provide cover to those properties affected by the autumn 2000 floods until December 2002, in an agreement made with the UK Government. In return, the Government provided assurances that significant investment in improving flood defences would be made during the post-2000 period. The Association of British Insurers (ABI) is presently working closely with the Environment Agency towards developing a more finely-tuned flood risk assessment process.

1.5.2 The repair of flood damaged domestic properties Following a serious flood event and on being notified by the (insured) homeowner, insurance companies arrange for a qualified loss adjuster, building surveyor and/or damage reinstatement company to visit the affected

6

Chapter 1

property. Most insurers have their own preferred companies which undertake this work. These professionals must determine the extent of damage caused, decide on an appropriate method of drying and agree the scope of works involved in the repair and reinstatement of the property. This can be a complicated process dependent on many factors, including the pre-incident condition of the house, the characteristics of the flood (e.g. depth, source, contaminant content) and the characteristics of the property (e.g. construction materials, construction form, age). At present, there exists little or no guidance to these professionals when undertaking such scoping works and in determining suitable drying approaches and repair strategies for individual elements within the property. A variety of solutions can be adopted for this work which, before the publication of this book, were largely determined based on the experience and preferences of the individuals concerned. As this currently involves a great deal of subjectivity, there exists a likelihood of conflict amongst professionals and homeowners. The situation is best demonstrated when one considers a hypothetical situation involving a row of terraced houses all affected by the same flood event and all more or less the same in respect of property condition and physical characteristics. However, one important difference between the properties is that they are likely to be insured by different insurers. As such, the professionals involved in the repair and reinstatement works will vary from one property to the next. Without any firm guidance or standardised procedures, the approach to drying and scope of repair works will largely depend on the views of the individual professionals and so may well vary significantly between properties.

1.5.3 The purpose of this book Guidance for reinstating flood damaged properties has been previously published. In the UK, the Building Research Establishment (BRE) has published several guidance notes for repairing flood damage. The BRE Scottish Laboratory provided guidance on the effects of flooding on building materials and fabric. The Construction Industry Research and Information Association (CIRIA) provide guidance on what repair procedures should be employed to repair a flood damaged property based on BRE publications. Similar guidance has also been published by the Department for Transport, Local Government and the Regions (DTLR). Although these guides are useful, they are primarily aimed at meeting the needs of homeowners and are therefore somewhat generic and lacking in detail for the various professionals involved in the repair and reinstatement of flood damaged domestic property. This book fulfils the need of the insurance and building repair industries by providing property professionals (building surveyors, loss adjusters, damage management companies), insurers and homeowners with the first definitive

Introduction to Flooding

7

guidance on the appropriate repair of flood damaged domestic properties. Based on the views of a substantial number of property experts, the first benchmark standards for the repair of flood damaged elements common in domestic property construction are provided. Knowledge of how to assess and subsequently repair flood damaged domestic properties is very important and will help insurance companies, loss adjusters, building surveyors, repair specialist contractors and homeowners to mitigate damage and return the property to its pre-flood condition as early as possible. Generally, this book will: .

.

.

.

Help to reduce and eliminate variations in repair recommendations. This ultimately will reduce conflicts between the parties involved (e.g. the insured and the insurer). Provide best practice standards for the industry (i.e. insurers and surveyors of flood damaged properties). This consequently will help to raise the level of service offered by insurers. Ensure that home owners are provided with optimum solutions to their particular flood damage. This will alleviate many of the concerns on behalf of the insured in respect of flood damage repair, and as a result lead to better customer satisfaction. Help reduce the cost and time involved in undertaking repair works and therefore improve overall efficiency and effectiveness of the reinstatement process.

These benchmarks represent the first attempt to standardise the reinstatement of flood damaged domestic properties and provide guidance to professionals involved in the damage management industry. However, each individual property will require detailed consideration of the many (e.g. technical and environmental) factors and, as such, these benchmarks will need to be applied according to the prevalent conditions.

1.6

Organisation of this book Chapter 1 has been a general introduction to flooding and the repair of flood damaged properties and outlines the main aims and objectives of the book. Chapter 2 presents an overview of guidance towards preparing for a flood event. The causes and effects of flooding are described, together with advice on assessing the risk of flooding. Additionally, guidance on flood prevention and flood protection, and a summary of flood resilient measures currently available to property owners is provided. Chapter 3 initially presents a theoretical framework for assessing flood damage to domestic properties. Currently there exists a high level of

8

Chapter 1

ignorance regarding flood characteristics in reinstating flood damaged properties. Then, the views of experts involved in the repair of flood damaged properties, regarding flood characteristics (including contaminant content, velocity, duration, sewage and fasciae content, source of the floodwater and floodwater depth), when undertaking an assessment of flood damage are presented. Methods currently used to identify these characteristics are also evaluated. Chapter 4 presents a review of methods used to dry out flooded buildings and then describes current practice with regard to methods and/or equipment currently employed, including guidance on sealing off sections of the building to assist drying, and tools used to determine if a building is sufficiently dry for repair works to commence. Chapters 5, 6, 7 and 8 represent the main contribution of the book and present the benchmarks for the reinstatement of a wide range of different flood damage conditions (including those for floor, walls, doors, windows and utilities commonly found in domestic properties). Overall, 37 flood damage conditions are considered, presented in the form of digital photos taken from real footage of flood damaged properties. A discussion of preferred remedial solutions, including their performance in terms of cost, quality, time and expected percentage of satisfied clients, is then presented. Optimal solutions (i.e. the ‘benchmarks’) for each flood condition are also presented and described. Here, a discussion of the performance of each possible solution for a particular flood condition is given, so that professionals involved in reinstating flood damaged domestic properties can predict with some confidence the outcomes of their chosen repair strategy in terms of cost, time, quality and customer satisfaction. Chapter 9 provides a summary of the benchmarks developed for the repair of flood damaged domestic properties. Recommendations for the industry and for further research which could help to further improve the repair and reinstatement of flood damaged properties are presented. Appendix A describes the characteristics of the experts involved in the research. Details and links to key websites relevant to property owners and professionals are included in Appendix B.

2 2.1

Preparing for a Flood Introduction Flooding is an inevitable phenomenon, and while it cannot be prevented there are a number of measures that property owners can implement to prepare for a flood event and therefore minimise the damage and disruption caused. This chapter provides a summary of key issues to be considered by owners and potential owners of property at risk of flooding.

2.2

Flood risk Seven per cent of the UK is likely to flood at least once in 100 years from rivers, with a further 1.5% at risk from coastal flooding. Flood risk assessment is not an exact science because of the vagaries involved in determining the likelihood of a flood event. However, it is recommended that some attempt be made to approximate this risk before considering the most effective ways to protect a property. This involves a combination of gauging both the likelihood of a flood event and the consequence or impact of that event on the property. After determining the level of risk, more appropriate decisions can be made regarding, for example, the decision to purchase a property or what type of flood protection measures can be usefully installed. The likelihood of a flood affecting a property can best be assessed by considering the past history of flooding in the area. The number of flood events and their magnitude in terms of depth, duration, source, etc., need to be considered. Additionally, consideration should be given towards what flood defence measures have been, or are about to be, implemented since the last flooding, as these may reduce the risk. Information on past flood history can be obtained from a variety of sources; probably the most accessible is that provided by local residents and neighbours. A note of caution here is warranted; the tendency for exaggeration, gross story telling and/or scaremongering is not unheard of. Other more reliable sources, including local authorities, local libraries, parish councils and the like, should be able to offer further information. The Environment Agency’s indicative flood plain maps provide a general overview of areas of land in natural flood plains that are at risk of flooding from rivers or the sea (excluding flash flooding). The maps make use of historical information and computer models of river flow to determine risks 9

10

Chapter 2

for areas defined on the basis of a postal code system. The maps take no account of flood protection schemes or other man-made flood defences; they therefore only provide a general indication of whether a property is in area that could be affected by river or coastal flooding. Flood probability data are not available for individual properties; however, the Agency is working on updating these maps and providing information on the likely frequency of flooding in different areas, taking the impact of flood defences into account; the results are due to be published in autumn 2004.

2.2.1 Flood warnings The Environment Agency provides a flood warning service in England and Wales, and aims to issue river and coastal flood warnings 2 hours before flooding starts. Warnings are not provided for localised flash flooding caused, for example, by blocked or overloaded sewers or local groundwater flooding, as these cannot be predicted. Warnings are issued through a variety of means, including: . . . . . .

direct to professional partners, parish and town councils and the public by telephone, facsimile, pager or email; radio and television weather bulletins; Environment Agency Floodline telephone and advice service; Environment Agency website; volunteer flood wardens; loudhailer messages.

Whilst groundwater flooding is not covered by the formal flood warning service, the Environment Agency provides information on groundwater levels and the risk of flooding by email, through Floodline and on their website. The Environment Agency does not issue flood warnings for surface water, non-main river and sewer discharge flooding. For information on events of this nature, severe weather warnings and Flood advice may be issued by the Met Office (see http://www.meto.gov.uk) via local and national TV and radio broadcasts.

2.2.2 Responding to flooding emergencies The emergency response to flooding falls primarily upon local authorities, working with the emergency services. Local authorities will co-ordinate evacuation, provide emergency accommodation and other social services; they hold supplies of sandbags for emergency use and, depending on availability, may be able to make some available to householders.

Preparing for a Flood

11

The Environment Agency’s first responsibility during flooding is to ensure that they take action to secure flood defences and operating sluices. They will, however, try to help with the emergence response, for example by providing any spare sandbags that are not needed for their own purposes. Following the recent flooding events in the UK, the Environment Agency held a number of flood awareness campaigns to make people aware of flood risks and what they should do if they receive a flood warning. Property owners can receive flood warnings direct to their home or work by telephone, facsimile or pager. However, people have to request or ‘opt in’ to receive warnings, and despite successive flood awareness campaigns since 1996, only one in four properties at risk have registered to receive flood warnings. The Agency actively encourages those at risk to prepare ‘flood plans’ for their property. The flood plan should identify the following: . . . .

communication links with family, friends and contacts; evacuation plans should this be required; emergency telephone numbers and contact details; how to turn off power supplies.

2.2.3 Property development Planning Policy Guidance Note 25: Development and Flood Risk (PPG 25) was published in July 2001 by the DTLR. The guide provides information for all parties involved in the planning and development process in England. Information is provided on how flood risk should be considered at all stages of the planning and development process in order to reduce future property damage and loss of life. PPG 25 aims to ensure that any development is safe and not exposed to serious flooding. The guidance requires that run-off from development should not increase flood risk elsewhere in the catchment, and that development must not constrain the natural function of the flood plain, either by impeding flood flow or reducing storage capacity. New development should therefore be located in zones of little or no flood risk wherever possible. Under PPG 25, new building works within areas of flood risk are only permitted in exceptional cases where the risks are managed and adequate flood defence measures and/or flood resistant construction techniques are adopted. Scotland and Wales have their own guidance information and policy for controlling development in flood prone areas. Where new development is proposed within areas of high flood risk, planning applications must be accompanied by a detailed and robust flood risk assessment for the site. The assessment should identify the likely speed with which flooding may occur, the duration, and likely social and environmental impacts.

12

Chapter 2

Consideration should be given towards raising floor levels above expected flood levels, the forms of construction (e.g. avoidance of basements) and to improving the flood resistance of the building fabric so that flood damage is minimised and properties can be re-inhabited as quickly as possible after floodwaters have subsided.

2.3

Causes and effects of flooding Flooding generally occurs through a combination of events, including heavy rainfall, coastal storms, blocked or overloaded drainage systems and sewers, excessive run-off and/or rising groundwater levels.

2.3.1 Sources of flooding According to the DTLR guide entitled Preparing for Floods (DTLR, 2002), the main sources of flooding are as follows: . . . . . .

rivers and streams; the sea; groundwater; overland flow (especially over tarmac and other hard surfaces); blocked or overloaded drains and sewers; broken water mains.

Rivers and streams River flooding can be caused by excessive rainfall, snow or hail, or a combination of high river levels and high tides. Flooding occurs when surface water run-off from the surrounding area exceeds the flow capacity of the river or stream. Property development and other activities have increased the risk of flooding from rivers and streams in many areas, and while the majority are protected by flood defences these cannot eliminate risk completely. The sea Flooding from the sea is usually caused by high tides, storm surges, waves overtopping or outflanking sea defences, or a combination of these factors. Groundwater This type of flooding is most likely to occur in areas of chalk or limestone and can take a long time to recede. It generally affects houses with basements that are prone to groundwater flooding or buildings located close to streams.

Preparing for a Flood

13

Overland flow Overland flows can be caused by heavy rain falling on saturated ground where groundwater levels are already high, or on areas of tarmac or concrete with inadequate drainage. Properties can be flooded by overland flows if they are located in areas where floodwater can accumulate. Blocked or overloaded drainage systems This type of flooding is unpredictable and often occurs in unexpected locations depending on the intensity of rainfall and condition of the drainage system. This ‘flash flooding’ can occur at any time of heavy rainfall when drainage systems become blocked or overloaded. Broken water mains Localised flooding can sometimes be caused by burst or broken water mains, although the damage caused is most likely to be restricted to basements.

2.4

Flood protection Keeping floodwater out of a property represents the most effective means of protection. Flood protection schemes fall into three categories: permanent flood defences, temporary freestanding barriers and removable household products. These range in scale and level of investment needed and are briefly described below.

2.4.1 Permanent flood defences These include major flood barriers (e.g. the Thames barrier) and flood embankments located on main rivers. DEFRA is responsible for sanctioning these defences and has to be assured that these are technically, environmentally and economically sound. As such, a rigorous analysis has to be undertaken before projects are given the green light. The Environment Agency is responsible for improving these permanent flood defences.

2.4.2 Temporary free-standing barriers These removable flood protection devices are normally installed some distance from a property or group of properties when a flood is imminent, for example by the local authority. They provide an effective barrier, as they prevent floodwater from reaching the property by holding it back or by

14

Chapter 2

deflecting it away. A further advantage is that they reduce the seepage of groundwater into foundations and ground floor of the property.

2.4.3 Removable household products These products are designed to seal potential flood routes into the property, such as doors, windows, air bricks, sewers and drainage systems. They may be installed fairly quickly by property owners immediately before a flood (i.e. on receipt of a flood warning) and should be removed as early as possible after the floodwater has receded. There are a wide variety of products available on the market which vary in their effectiveness. The Environment Agency and H.R. Wallingford have recently launched a British Standards Institute (BSI) kitemark for approved products, although few have so far been granted approval. The scheme provides assurance to users of flood protection products that these have been independently tested and manufactured in accordance with the specification. The Construction Industry Research and Information Association and the Environment Agency have published a new guide entitled Flood Products: Using Flood Protection Products (CIRIA and Environment Agency, 2003) to coincide with the new kitemark scheme, which is available free of charge from the Environment Agency.

2.5

Flood resilient repairs There are also a range of more permanent measures that can be implemented to improve the flood resistance of existing buildings. These are normally installed as part of the repair following a flood, but could be installed in anticipation of damage, if required, or during refurbishment, for example. New developments at risk of flooding should seek to incorporate as many flood resilient measures as possible. A range of measures exist that vary in terms of their practicability, effectiveness in reducing damage caused by flooding of differing depths and durations, and benefits in reducing subsequent insurance claims. These measures concern various aspects of domestic property including floors (e.g. replacing timber floors with solid concrete floors), walls (e.g. installing air bricks above the expected flood level and then ducting down into the floor void), interiors (e.g. fitting kitchen units with extendable plastic or stainless steel fittings) and services (e.g. moving electrical sockets to at least 1 metre above floor level). The Association of British Insurers (ABI) has recently published a report on the cost and effect of installing such measures (ABI, 2003). For flood proofing measures that reduce repair costs in the long term, each building must be treated individually; there are few hard and fast rules that will apply to all. More detailed guidance is

Preparing for a Flood

15

also available on the Environment Agency website, the address of which is given in Appendix B.

2.6

Summary This chapter has provided an indication of the range of measures available to property owners in order to prepare for a flood event. How to assess the likelihood of a flood has been described and the causes and effects of flooding have been discussed. Flood protection measures available to property owners and an introduction to flood resilient features have also been presented. The next chapter presents a framework for assessing flood damage to domestic properties, and then focuses on key flood characteristics to be considered when undertaking an assessment of flood damage.

3 3.1

Flood Characteristics Introduction This chapter initially presents a theoretical framework for assessing flood damage to domestic properties, which is deemed as a function of building and flood characteristics. Currently there exists a high level of ignorance regarding flood characteristics in reinstating flood damaged properties. This will be demonstrated to readers and then explanation given on how these characteristics influence the extent and nature of flood damage (including the cleaning procedures and ultimately the cost of overall reinstatement work). Based on this, the views of experts involved in the repair of flood damaged properties, regarding flood characteristics (including contaminant content, velocity, duration, sewage and fasciae content, source of the floodwater and floodwater depth), when undertaking an assessment of flood damage are presented. Methods currently used to identify these characteristics are also evaluated.

3.2

Flood damage function Flood damage to domestic properties is essentially a function of two independent but inherently related factors, building characteristics and flood characteristics, which may be formalised as (Nicholas et al., 2001): Flood damage ¼ f Flood characteristics þ Building characteristics

The following sections describe building and flood characteristics which influence the amount of flood damage.

3.2.1 Building characteristics The building characteristics that influence flood damage include mainly the type of materials and their drying characteristics, the frequency of the dwelling being flooded, and the building condition before being flooded (Nicholas et al., 2001). It is well recognised that the structures of many UK properties comprise porous/permeable solids (e.g. brick, block, concrete, plaster, render). Therefore, knowledge of how these elements react after exposure to floodwater needs primary consideration. Gummerson et al. (1980, p. 19) identified that capillary absorption in clay brick and autoclaved aerated concrete

16

Flood Characteristics

17

block materials followed a linear relationship of t½ (where t ¼ time); this means, the longer such a material is exposed to floodwater, the greater the amount of water absorbed (albeit at a reducing rate). Flooding in the UK can sometimes last for extended periods (days or weeks) (PPG 25, 2001), so it would seem logical that consideration of the floodwater ‘contact time with the building’s structure’ would be a contributory factor in any flood repair guide or flood cost model (e.g. Debo, 1982; McBean et al., 1988; Handmer and Smith, 1990). However, present literature regarding the physical damage that flooding can inflict tends to ignore this time factor (Nicholas et al., 2001). Intrinsically linked to this is the amount of time necessary to dry the damaged building. A flood damaged property must be dried before any repair works can be commenced to reduce the probability of mould growth, avoid timber rot and thereby minimise the likelihood of subsequent rework. Therefore, knowledge of moisture transportation in materials is essential for robust decisions in this respect. This subject will be discussed in the next chapter. The frequency of the building being flooded is closely related to its physical and geographical location (PPG 25, 2001). Green and Suleman (1987) made the interesting claim that those buildings that are frequently flooded tend to undergo less damage than those that are flooded infrequently. This is because occupiers of ‘frequently’ flooded buildings tend to be more prepared for flood emergencies; hence, fittings and furnishings installed are those that can be more easily moved to ‘dry safety’ (Green and Suleman, 1987). Although the construction of flood defence measures, such as dams or flood skirts, may reduce the probability of a building being flooded, these can not totally eliminate the risk (McCrory et al., 1976). The building’s condition before being flooded is also an eminent factor influencing flood damage, as most insurance products provide for the reinstatement of a property to its pre-incident condition. In particular, a large proportion of the existing housing stock is in a state of disrepair and poor maintenance (Rolfe and Leather, 1995).

3.2.2 Flood characteristics Damage caused by disasters is highly dependent on the scale and nature of that disaster. Here, the damage caused to a property is dependent on the flood characteristics, in terms of depth, velocity flow, contaminant content and time duration. In the UK, the Building Research Establishment (BRE) has published a number of documents on repairing flood damaged properties (BRE, 1984; 1991; 1997a, b, c, d). These publications provide basic instructions, but tend to ignore many of the characteristics of the flood that (inevitably) impact the extent of damage caused and any associated necessary remedial actions. Publications by the Federal Emergency Management Agency (FEMA, 2003) and the Building Research Association of New Zealand (1984) take a similar

18

Chapter 3

approach to that of the BRE. Hence, present flood repair guidance fails to consider the characteristics of the flood that has occurred, and hence is likely to be flawed, inaccurate and/or inconsistent. These flood characteristics are now discussed. Flood depth As discussed previously in Chapter 1, section 1.4, flood depth is the primary factor influencing the scale of flood damage (DTLR, 2002). This is usually as a result of increased hydraulic pressure on the building’s components, and abrasion or scouring. The impact of flood depth on the damage incurred has been the subject of much research (e.g. Debo, 1982; Sorkin, 1982; Green and Suleman, 1987; McBean et al., 1988; Handmer and Smith, 1990; Minnery and Smith, 1996). Generally, as the depth of the floodwater increases, so does the cost of necessary repair works (Nicholas et al., 2001). The DTLR (2002) stated that for very shallow flooding, where water does not rise above floor level, damage is unlikely to be significant for most properties. Damage increases significantly once water rises above the floor level and comes into contact with furnishings and personal belongings. Flood depths greater than one metre above floor level may damage the structure of the building. Typically, half a metre of floodwater within a modern semi-detached house will result in damage costing on average £15 000 to repair and a requirement for around £9000 to replace damaged belongings (cf. DTLR, 2002; ABI, 2003). Velocity of floodwater The velocity of floodwater is strongly related to the distance from the flood source and hence the depth of floodwater. Xu et al. (1998) demonstrated that the greater the distance from the flood source, the lower the floodwater velocity, and consequently the smaller the capacity of the floodwater to transport quantities of solid matter. Furthermore, deeper floods have an increased velocity and on recession can have a natural tendency to ‘wash out’ suspended particles of deleterious matter as the floodwater level recedes (Nicholas et al., 2001). Generally, it is well accepted that the greater the floodwater velocity, the greater the probability of structural damage. Floodwater contaminants It is also important to consider floodwater contaminants when assessing flood damage because these may: .

influence the water absorption characteristics of the building materials used;

Flood Characteristics

. .

.

19

influence the drying time of materials; transport embryonic forms into the building’s structure that are difficult to remove without saturation or sterilisation, and which may become a danger to occupiers’ health; and significantly influence repair costs through the work involved in the removal of physical deposits (Nicholas et al., 2001).

The nature of floodwater contaminants may range from sewage from blocked drains to chemicals from garages or commercial premises. Once floodwater recedes, a layer of contaminated silt is often left behind. Here, thorough cleaning is essential to ensure that the dwelling is free from germs and fit for operatives to conduct any necessary repair works and for occupants to live healthily in their dwelling. In cases of flooding from the sea, saltwater can lead to corrosion of metallic fittings, such as metal ducting and switch boxes, and steel reinforcement in reinforced concrete. It is estimated that saltwater flooding can increase flood damage repair costs by around 10% (cf. DTLR, 2002; ABI, 2003). It is clear that contaminant content will influence repair methods and the cost of repair works. However, literature suggests that, at present, flood damage assessment generally ignores factors relating to contaminant content. For example, the Scottish Office Development Department (1996, p. 9) considered floodwater that contained salt, silt and sewage. However, it was stated that the risks associated with contaminants are overstated because rainfall was found to dilute such substances; thus the true impact of contaminants in floodwater and the damage caused to flooded properties is not presently known (Nicholas et al., 2001). Duration The duration that the floodwater is in contact with the building is also a key factor determining the level of damage. Generally, the longer the duration of the flood, the more damage it will cause to the building. This is mainly because many UK properties are constructed of porous solid materials, such as bricks, blocks and concrete; hence, the longer the flood duration, the more floodwater absorbed by the buildings’ materials, which will prolong subsequent drying and repair works. Widespread ignorance of these flood characteristics in flood damage assessment indicates that the damage caused is considered by many practitioners to be a simple problem to resolve, whereas in reality it is complex. As a first step to impart knowledge of flood characteristics, it is important that the perceptions of flood damage assessors regarding these characteristics are identified. An overview of the current understanding and practice will be provided which may serve as a basis for determining future training needs. The perceptions of experts responsible for the reinstatement of

20

Chapter 3

flood damaged properties in regard to flood characteristics are now presented.

3.3

The importance of flood characteristics With the aim of ascertaining the importance of the flood characteristics, 289 experts (see Appendix A for a detailed description of data collection), when assessing flood damage, rated the importance of several key flood characteristics on a four-point scale ranging from 1 indicating ‘do not consider when making a damage assessment report’ to 4 indicating ‘very important’. Measures of central tendency (mean, median and mode) were used for the analysis. Additionally, Pearson’s correlation tests were performed to investigate the relationships between levels of experience and levels of importance for various flood characteristics. Figure 3.1 presents the respondents’ perceived importance of flood characteristics, including contaminant content, velocity, duration, sewage and fasciae content, source of the floodwater and floodwater depth. Table 3.1 summarises the importance of these characteristics; based on the mean importance, the characteristics were then ranked. Sewage and fasciae content of floodwater was considered the most important characteristic, followed by contaminant content, depth, duration, source and velocity of floodwater. The mean, median and mode of contaminant content and depth of floodwater were the same and therefore assigned the same rank. Generally, respondents regarded the characteristics to be of importance since the means indicated importance levels between 3 and 4. That is, most respondents deemed the characteristics to be ‘important’ or ‘very important’, with velocity of floodwater being the exception. On closer examination of Figure 3.1 and Table 3.1 (specifically the means and modes), conceptually, flood characteristics could be classified into three groups. The first group comprises sewage and fasciae, contaminant content, and depth of floodwater; these represent ‘extremely important’ flood characteristics where most respondents classified them as ‘very important’. The second group includes duration and source of the floodwater; these characteristics were generally perceived as ‘important’, with some respondents classifying them as ‘very important’. The third group includes velocity of floodwater which was deemed an ‘important’ characteristic; however, a reasonable number of respondents perceived it as ‘slightly important’. These results suggest that the ‘content’ and ‘depth’ of floodwater are considered the most destructive and costly. Two possible reasons may help explain why velocity was found to be the least important characteristic. Firstly, assessors of flood damage are not normally in the premises when the disaster occurs

80

30 20

0

very Important

10

very Important

Important

40 30 20 10

SOURCE OF FLOODWATER

Figure 3.1

slightly Important

50

0

very Important

20

60

Important

30

Important

20

slightly Important

40

Percentage of respondents

50

slightly Important

40

SEWAGE AND FASCIAE CONTENT

DURATION

do not consider

60

very Important

Important

slightly Important

do not consider

10

VELOCITY

very Important

40

0

0

Important

CONTAMINANT CONTENT

0

10

very Important

Important

slightly Important

0

do not consider

10

20

slightly Important

20

30

do not consider

30

21

40

do not consider

40

50

do not consider

60

50

Percentage of respondents

Percentage of respondents

50

60

Percentage of respondents

Percentage of respondents

70

Percentage of respondents

Flood Characteristics

FLOODWATER DEPTH

Importance of flood characteristics

and therefore do not visually assess its impact. Secondly, the flow velocity of UK floods is somewhat lower than, for example, floods due to tsunami and therefore velocity may not be considered a very destructive factor when properties in the UK are flooded.

22

Chapter 3

Table 3.1

Mean, median and mode of the importance of flood characteristics

Flood characteristics Sewage and faeces content Contaminant content Depth Duration Source Velocity

Mean

Median

Mode

Rank

3.67 3.52 3.52 3.33 3.26 2.59

4.00 4.00 4.00 3.00 3.00 3.00

4 4 4 3 3 3

1 2 2 4 5 6

Note: For mean, median and mode, the numbers mean the following: 1, do not consider when making a damage assessment report; 2, slightly important; 3, important; 4, very important.

Table 3.2 Correlation matrix between levels of experience and levels of importance Contaminant Velocity Duration Duration in present job (yrs) Length of experience (yrs) Properties surveyed in past 2 yrs Properties surveyed in past 5 yrs Properties surveyed in past 10 yrs

Sewage

Source

Depth

0.021

0.037

0.003

0.046

0.007

0.042

0.071

0.051

0.042

0.121*

0.037

0.049

0.173**

0.072

0.214**

0.085

0.196**

0.164**

0.191**

0.074

0.219**

0.103*

0.188**

0.147**

0.194**

0.057

0.190**

0.107*

0.170**

0.140**

Note: * Correlation is significant at the 5% level (one-tailed); ** Correlation is significant at the 1% level (one-tailed).

Table 3.2 shows a correlation matrix investigating the relationships between respondents’ levels of experience and their perceived levels of importance towards flood characteristics. There was strong evidence (at 99% confidence level) of positive relationships between the importance of contaminant content, duration, source and depth of the floodwater, and the number of properties surveyed over the past 2, 5 and 10 years. This suggests that experts with more experience consider contaminant content, duration, source and depth of the floodwater to be more important. Furthermore, there was some evidence (at 95% confidence level) of a relationship between sewage and fasciae content, and the length of experience and number of properties surveyed over the past 5 and 10 years.

3.4

Sources of information or methods to determine flood characteristics Figure 3.2 presents the source of information and methods currently used by practitioners to determine various flood characteristics. Findings are discussed in the following paragraphs.

Flood Characteristics

Figure 3.2

Methods used to determine flood characteristics

23

24

Chapter 3

Figure 3.2

Continued.

Flood Characteristics

25

In determining contaminant content, and sewage and fasciae content, of floodwater, more than half of the respondents (60.1% and 56.2%, respectively) relied on visual inspection of the premises. The second most popular method was to employ independent consultants (37% for both characteristics). About one-third would obtain information by contacting the public health department of the local authority (24.9% and 35.9%), water authority (30.6% and 25.6%) and the Environment Agency (30.6% and 32.0%). Some (21.0% and 17.4%) would contact the local authority. Only a few (4.3% and 4.6%) would utilise in-house laboratories, probably due to a lack of such facilities and the expense involved. Visual signs of subsidence was the most popular method (77.0%) employed to determine the velocity of floodwater. Some respondents (28.0% and 23.3%) would contact the Environment Agency and water authority to obtain information. The importance of local information and/or consultation with witnesses was highlighted in determining the duration of the flood, with almost half of the respondents (46.5%) indicating an intention to seek local assistance. However, visual inspection of the flood was still the dominant method employed (57.0%). Additionally, various sources of information would be sought by some respondents, including contacting the Environment Agency (26.4%), water authority (25.0%) and local authority (23.6%). Similarly, various sources of information would be sought to determine the source of floodwater, with visual inspection as the most dominant method (53.7%). About 30% of respondents sought assistance from the Environment Agency (36.4%), water authority (35.7%), local authority (28.3%), and local information/witnesses (27.9%). Additionally, independent consultants (19.1%) and public health departments of local authorities (15.5%) were also deemed useful sources of information by some respondents. In-house laboratories were again less utilised (3.2%). Almost all damage assessors (93.9%) would visually inspect premises to determine the floodwater depth, probably because flood marks on the walls may be easily recognisable after the flood has receded; 41.8% would also test the moisture content of the building. Here, other methods were seldom utilised. Generally, flood damage assessors relied heavily on visual inspections and hence independent judgements. In a similar vein, local information and/or witnesses were also important sources of information, particularly for determining the duration of the flood. This suggests that current assessment of flood-damaged properties contains elements of subjectivity and may therefore be prone to variation. Further, it may be concluded that in the absence of hard evidence and hence the inability to obtain objective information, assessors would often tend to pursue other sources of information (e.g. from witnesses of the flood), particularly when determining contaminant content,

26

Chapter 3

sewage and fasciae content, duration of flood and source of floodwater. In contrast, current practice relies heavily on visual inspection to determine floodwater depth.

3.5

Summary This chapter has described findings regarding the importance of various flood characteristics (including contaminant content, velocity, duration, sewage and fasciae content, source of the floodwater and floodwater depth), and sources of information or methods used to determine them. Sewage and fasciae content of floodwater was considered to be the most important characteristic, followed by contaminant content, depth, duration, source and velocity of floodwater. Although flood ‘content’ was the most important characteristic, currently little research has been done to model and/or establish relationships between flood ‘content’ and the damage incurred. Most experts deemed the other listed characteristics to be ‘important’ or ‘very important’, with velocity of floodwater being the exception. Further investigation suggests that experts with more experience give more consideration to flood characteristics, apart from velocity of floodwater. This underlines the need to impart knowledge to novice damage assessors. The results of analysis regarding the source of information and methods to determine various flood characteristics suggest that flood damage assessors relied heavily on visual inspections (i.e. independent judgements) and local information and/or witnesses, indicating that current assessment of flood damaged properties contains subjective elements and may therefore be prone to variation. Further, in the absence of hard evidence and hence the inability to obtain objective information, assessors would often tend to pursue other sources of information (e.g. from witnesses of the flood), particularly for determining contaminant content, sewage and fasciae content, duration and source of floodwater; however, current practice relies heavily on visual inspection to determine floodwater depth. The next chapter discusses the drying out of flooded buildings.

4 4.1

Drying Out Flooded Buildings Introduction This chapter first presents a review of methods used to dry out flooded buildings and then describes current practice regarding methods and/or equipment employed, including guidance on sealing off sections of the building to assist drying, and tools used to determine if a building is sufficiently dry for repair works to commence.

4.2

Background information Gummerson et al. (1980) described in detail the capillary transportation of water in masonry structures: there is a linear relationship between the cumulative absorption of fluid versus the square root of time; those materials with large pores have significantly lower sorptivities1 than those materials with fine pores, regardless of the initial porosity of the materials. Following the identification of various materials’ sorptivity characteristics, wetting and drying curves were then constructed (Gummerson et al., 1980, p. 22) to illustrate graphically the pressure that is required to remove water from a material’s pore matrix (see, for example, Figure 4.1). In the majority of construction materials wetting and drying curves differ in shape because the pore voids are not of uniform diameter throughout the material. Hence, the length of time during which floodwater was in contact with the building structure and the sorptivity characteristics of the building’s materials must be considered when predicting drying out times accurately. Hall et al. (1984) specifically concentrated their research on water evaporation and the drying process in brick and block materials. The process of drying was defined as ‘unsaturated flow liquid within the porous solid; vapour flow within the porous solid; the liquid–vapour phase change; and convective–diffusive transfer of vapour from the surface of the solid to the surroundings’. Because of these sub-processes of unsaturated flow theory, it was hypothesised that drying of porous materials would depend markedly on external factors as well as on the material’s properties. Hall et al. (1984) admit that in developing their theory of drying of building materials they have aimed to avoid needless complexity whilst retaining physical validity. 1

Sorptivity is defined as the absorption of a liquid into a material, containing empty or partially empty pores, via capillary attraction (Illston, 1994, p. 171).

27

Chapter 4

25

Capillary Potential 102kPa (Suction pressure exerted by material’s pores)

28

20

15

10

5

0 0

0.5

Empty

1.0 Saturated

Water Content

denotes typical ‘wetting’ curve denotes typical ‘drying’ curve (Curves are not to scale)

Figure 4.1 Absorption characteristics of a common clay brick (after Gummerson et al., 1980 with permission from the Chartered Institute of Building)

To observe the drying behaviour of clay bricks, Hall et al. (1984) saturated specimens with water under vacuum conditions and then allowed them to be dried under constant conditions of air flow, air temperature and air humidity. The bricks were then weighed and the amount of water evaporated after certain predetermined time periods was noted. Two distinct stages of drying were observed: the first stage (stage I) is called the constant drying rate period, whilst the second stage (stage II) is known as the falling drying rate period. By considering both stages in isolation, Hall et al. (1984, p. 14) concluded that ‘because the first stage of drying appears to be essentially uninfluenced by material properties, it is generally accepted that free evaporation of liquid is occurring at the solid surface. Thus, the rate of drying is controlled by the vapour properties of the evaporating substance – its saturated vapour pres-

Drying Out Flooded Buildings

29

sure po and its binary diffusion coefficient in air Dv .’ They suggested that increasing the air speed is probably the most cost effective method of increasing the stage I drying time, which might be achieved by using fans or even by good natural ventilation within a building. Hall et al. (1984) further provided a simple guide to evaporation rates as presented in Table 4.1. Having discussed drying of a single composite material (brick or block material), it is worth considering water movement in two ‘joined’ porous building materials. There are numerous examples of composite layers in building construction, e.g. plaster onto brick or blockwork, render onto brick or blockwork, skim plaster onto plasterboard. Because of the large number of construction techniques which have two (or more) composite porous materials joined together, knowledge of water movement in such composites is relevant to this chapter. Wilson et al. (1995a, b) conducted research into the absorption of water into a composite bar consisting of two dissimilar materials which were ‘joined’ by hydraulic contact. They concluded that the absorption rate through a material of higher sorptivity into one of lower sorptivity decreases immediately after the wet front passes the junction of the two materials. After the wet front has passed the junction between the materials, the first material becomes saturated and the rate of water absorption becomes dependent upon the rate of absorption into the second material. Hence, the second material controls the absorption of fluid into the composite. Similarly, for absorption through a material of lower sorptivity into a material with higher sorptivity, the rate of water absorption depends upon the sorptivity characteristics of the second material. Again the second material controls the absorption rate. This means that the duration of flooding is critical to the amount of water that can be absorbed by a composite material. For instance, if the flooding period is very short and the first layer of the composite does not become saturated, then water absorption by the second layer is less likely. It is also evident that the sorptivity characteristics of the materials exposed to flooding are significant in influencing the quantity of water absorbed. Before commencement of reinstatement work, it is crucial that the material’s level of ‘dryness’ is determined so that the likelihood of reworking is reduced. In this regard, Dill (2000) provided technical guidance on a range of techniques available for determining moisture present in building elements Table 4.1 Drying rates of brick walls under certain weather conditions (after Hall et al., 1984 with permission from Elsevier) Weather conditions For a few hours after driving rain Over a 4 day period after driving rain Other average rates

Evaporation rate (average) [g m 68 20 1–7

2

h 1]

30

Chapter 4

and which method(s) are the most appropriate for assessing a particular situation. Although useful, this guidance does not provide measures of the effectiveness of these various techniques as used in practice. When considering practical issues associated with drying out buildings, the BRE (1974) suggested three principal methods that could be used: the use of natural ventilation by keeping windows open, the use of heaters and opening of windows, and the use of dehumidifiers and closing of windows. This demonstrates the uncertainty that exists concerning effective drying methodologies, a point exacerbated when one considers the plethora of ‘drying equipment’ (dehumidifiers, fans, heaters) and ‘drying experts’ available in the marketplace. In sum, the literature describes the occurrence of water absorption in building elements and practical methods to dry them. Presently, there is lack of knowledge of the effectiveness of various drying methods, including how to determine if a building is sufficiently dry for repair works to commence. This book attempts to address these issues and presents the views of a large sample of experts in this field. The following sections present the research findings.

4.3

Methods and/or equipment employed to dry flood damaged buildings Experts (see Appendix A for a detailed description of data collection) were asked to indicate and rate the effectiveness of the equipment and procedures presently and ideally used to dry a flood damaged building the temperature of which ranges from 08C to 108C. This was to reveal any possible constraints or external factors (e.g. the need to minimise cost) that may influence what equipment is currently being used in practice. A list of options for drying out flooded buildings was provided and respondents were allowed to choose one or more of those considered appropriate. They were then asked to indicate the effectiveness of their preferred method on a five-point scale, where 1 indicates ‘very poor’, 2 ‘poor’, 3 ‘average’, 4 ‘effective’ and 5 ‘very effective’. These levels of effectiveness allowed comparison between methods. To ensure validity and reliability, methods compared had to accumulate a minimum of ten responses. Present drying methods (i.e. equipment and/or procedures currently used) are listed in Figure 4.2; their perceived effectiveness is shown in Figure 4.3. Figure 4.2 shows that a majority of respondents (74.7%) turned on the existing heating system to assist drying, a method considered to be practical and timely; 50.9% simply allowed the dwelling to dry with natural ventilation; however, 63.5% would use fans to increase ventilation. The use of dehumidifiers was quite significant (51.3% and 69.0%). Although the least popular

Drying Out Flooded Buildings

31

option, quite a considerable number of respondents (43.3%) would install temporary heating to help dry the flooded building. These findings suggest that experts consider using various methods to assist drying rather than focus on a single dominant method. Figure 4.3 illustrates that although it was the most popular method, use of the existing heating system was perceived to be the second least effective (3.11) after natural ventilation (2.55). The most effective methods were the use of dehumidifiers (refrigerant, 3.80; desiccant, 3.84). The use of fans (3.39) was perceived to be the third most effective method. The use of temporary heating (3.16) was considered more effective than the use of existing heating systems (3.11), although the difference was marginal. Generally, with the exception of

Figure 4.2

Present methods used to dry a flood damaged building

Figure 4.3

Effectiveness of present drying methods

32

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natural ventilation, all other methods were perceived to be somewhat effective. Natural ventilation was perceived to be less satisfactory than the other drying methods. Ideal drying methods are listed in Figure 4.4 and their effectiveness is presented in Figure 4.5. About forty per cent (41.2%) of the respondents indicated that their ideal drying methods would be different from existing drying methods. In other words, more than one-half would not use different methods from their present methods even if they were allowed to do so (i.e. if there were no constraints). The most popular ideal drying method was to install temporary heating as indicated by 16% of respondents. Interestingly, natural ventilation was the second most popular method, although only

Figure 4.4

Ideal drying methods

Figure 4.5

Effectiveness of ideal drying methods

Drying Out Flooded Buildings

33

(9.7%) indicated such an ideal preference. Assisting drying with the existing heating system was the least popular method (4.0%). Generally, the perceived effectiveness of the ideal drying methods (with the exception of refrigerant dehumidifier) was higher than those of the present drying methods (refer to Figures 4.3 and 4.5). Notably, the effectiveness score of natural ventilation improved from 2.55 to 3.85 as the ideal method. The perceived efficacy of this method may be linked to the relatively lower costs involved. However, while this method may be considered the most effective, the time taken to dry buildings this way may preclude its use. Considerable improvement in effectiveness score was also observed in the use of temporary heating systems. Overall, the use of desiccant dehumidifiers was considered the most effective way to dry flooded buildings. Respondents were also asked to indicate the number of dehumidifiers to be installed. Various methods of determining the number of dehumidifiers to be installed in a flood damaged property were identified by 77.3% of the respondents and the results are presented in Figure 4.6. Property size (in terms of volume, area, number of rooms) was the most important determinant as identified by 46.3% of the respondents. About one-third (32.2%) considered this task to be outside their expertise and would seek advice from specialists/ contractors. The capacity of available dehumidifiers (14.5%) was also an important consideration to be matched with the property size. It is interesting to note that some respondents would rely on experience-based trial and error

Figure 4.6 Methods used to determine the number of dehumidifiers to be installed in a flood damaged property

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(8.9%) or use the generalisation of one dehumidifier per room or two per standard semi-detached house (10.3%). This indicates that for some, drying out is not a scientific process but rather one based on experience and subjectivity, the reliability of which must be doubted.

4.4

Sealing off sections of the building to assist drying Sealing off sections of the building is often an appropriate strategy to enhance the effectiveness and efficiency of the drying equipment and hence should accelerate the drying process. This section presents the findings of whether the experts employed this strategy, and methods to determine the number of sections. Here, respondents were also asked to indicate the types of heaters (if used) by selecting from a range of options provided. About two-thirds (63.5%) of the respondents sealed off sections of the property to assist the drying procedure. Methods used to determine the number of sections are presented in Figure 4.7. Most (63.6% of those who sealed off sections of the property) indicated that the number of sections was dependent on each individual project. This suggests a high level of subjectivity on behalf of the flood damage assessors. Some respondents indicated ‘more scientific’ methods including the capacity of dehumidifiers (24.2%) and the volume of each room (23.0%). Some indicated more ‘practical’ methods, including the sealing of each room individually (15.2%) and

Property owner comfort and health considerations

0.6

Upper and lower floor separation

1.8

Dependent on each individual project needs

63.6

Evaluated on the capacity of the dehumidifiers

24.2

Dependent on the volume of each room

23.0

Seal each room individually

15.2

0

10

20

30

40

50

Percentage of respondents

Figure 4.7

Methods used to determine number of sections

60

70

Drying Out Flooded Buildings

Figure 4.8

35

Types of heaters used to assist drying

separation of the upper and lower floors (1.8%). Very few assessors took into account the comfort of the property owner and health considerations (0.6%). Experts who sealed off sections of the property and installed heaters to assist drying were also asked to indicate the types of heaters presently used; the results are shown in Figure 4.8 where 75.0% used electric warm air heaters, while some used gas fire heaters (18.1%) and electric radiant type heaters (14.6%). Very few utilised electric bar type heaters (2.8%) or a combination of dehumidifiers and central heating systems (2.8%). The use of air movers/fans was even more uncommon (1.4%). One expert indicated an aversion to the use of heaters as these were said to cause cracks in materials due to the effects of rapid drying.

4.5

Methods and/or equipment employed to determine if a building is sufficiently dry for repair works to commence This section concerns the methods and/or equipment presently and ideally employed to determine if a building is sufficiently dry. As before (section 4.3), experts were given options and perceived effectiveness was measured on a five-point scale. Figure 4.9 depicts methods currently used to determine whether a building is sufficiently dry for repair works to commence; Figure 4.10 presents the perceived effectiveness of these same methods. The most popular method is visual observation which was used by 79% of the respondents; rather surprisingly, this method was perceived as being the least effective (2.63). The second

36

Chapter 4

Figure 4.9 Present methods used to determine whether a building is sufficiently dry for repair works to commence

Figure 4.10 Effectiveness of present methods used to determine whether a building is sufficiently dry for commencement of repairs

Drying Out Flooded Buildings

37

most popular method was to use electrical resistance meters (40.8% of respondents). These meters are rather unreliable because of the presence of salts in masonry (Dill, 2000, p. 26) so high moisture levels may be indicated when, in fact, there is only a high salt content. This suggests a lack of knowledge regarding the use of appropriate methods for determining dampness levels. Humidity sensors (36.3%), electrical capacitance meters (32.1%) and calcium carbide moisture meters (27.1%) were also utilised. Other experts (31.7%) simply allowed a predetermined number of days to pass after the flood before repair works were commenced. Several methods, including microwave moisture gauges (7.3%), electrical earth leakage techniques (4.2%), radar (2.3%), nuclear magnetic resonance (1.9%) and thermographic inspections (1.9%) were utilised by a minority of respondents. Apart from the subjective methods (e.g. those based on visual observation or which allow a set number of days after the flood), the differences in effectiveness of the various methods were marginal. The most effective method was perceived to be use of calcium carbide moisture meters (3.68). The subjective methods were perceived to be the least effective (2.63) but, ironically, were used quite extensively. Ideal methods for determining if a building is sufficiently dry for repair works to commence and their effectiveness are presented in Figures 4.11 and

Figure 4.11 Ideal methods for determining whether a building is sufficiently dry for repair works to commence

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Chapter 4

Figure 4.12 Effectiveness of ideal methods used to determine whether a building is sufficiently dry for commencement of repairs

4.12, respectively. The ideal methods of 44.7% of the respondents were different from present methods. Humidity sensors were the most popular ideal method as identified by more than 22.5% of respondents. Thermographic inspection was the second most popular ideal method (18.3%); however, this is rarely used at present (Figure 4.9). Subjective methods, including visual observation (0.4%) and allowing a set number of days after the flood (1.5%), were not considered ideal by most; these results suggest that practitioners are aware of the ineffectiveness and inaccuracy of such methods and would prefer to use alternative approaches. Generally, perceived effectiveness of all methods improved in the ideal scenario (Figures 4.10 and 4.12). In fact, calcium carbide moisture meters and thermographic inspections were considered more than ‘effective’, i.e. scored more than 4 on the five-point effectiveness scale. Differences in the effectiveness between other methods were marginal.

4.6

Summary This chapter has discussed various aspects of drying out flooded buildings, including methods and/or equipment employed for drying, sealing off sections of the building to assist drying, and methods and/or equipment used to determine if a building is sufficiently dry for repair works to

Drying Out Flooded Buildings

39

commence so that subsequent repair works are not damaged by latent defects such as fungal attack. Findings suggest that experts would consider using various methods to assist drying rather than focusing on a single dominant method. The most popular method was to turn the existing heating on, a method considered to be practical and timely. The most popular ideal drying method was to install temporary heating; this was followed in popularity by use of natural ventilation. Property size (in terms of volume, area, number of rooms) was the most important factor in determining the number of dehumidifiers to be installed in a flood damaged property. Some damage assessors would rely on experienced-based trial and error or the generalisation of one dehumidifier per room or two per standard semi-detached house. This indicates that for some, drying out is not a scientific process but rather one based on experience and subjectivity. Two-thirds of the experts sealed off sections of the property to assist drying out. A high degree of subjectivity was again found in determining the number of sections to be sealed off. Furthermore, findings suggest a lack of knowledge regarding appropriate methods of determining dampness levels, and a reliance on subjective methods (i.e. those based on visual observation or which allowed a predetermined number of days after the flood for drying). These methods were perceived to be the least effective but ironically were used quite extensively. The most effective perceived method was the use of calcium carbide moisture meters. These facts highlight a lack of definitive guidance on the various aspects of drying out flooded buildings. The next chapter presents and discusses the first benchmarks for repairing flood damaged property and is concerned in particular with the reinstatement of flood damaged floors.

5

5.1

Reinstatement of Flood Damaged Floors Introduction This and three subsequent chapters represent the main contribution of this book and present the benchmarks for reinstatement of a wide range of different flood damaged conditions (including those for floor, walls, doors, windows and utilities) common in domestic properties. Overall, 37 flood damage conditions are considered and presented in the form of digital photos taken from real footage of flood damaged properties. A discussion of the preferred remedial solutions as indicated by experts, including their performance in terms of cost, quality, time and expected percentage of satisfied clients, is then presented. Optimal solutions (i.e. the ‘benchmarks’) for each flood condition are also presented and described. A discussion of the performance of each possible solution for a particular flood condition is given so that professionals involved in reinstating flood damaged domestic properties can predict with some confidence the outcomes of their chosen repair strategy in terms of cost, time, quality and customer satisfaction. With these benchmarks, flood damage assessors will be able to consider the performance of various repair strategies and thereby recommend one appropriate strategy for a particular flood damage condition. However, readers should not interpret these benchmarks as ultimate solutions because conditions such as environmental factors may vary from one property to another. Nevertheless, these benchmarks represent the first attempt to standardise the reinstatement of flood damaged domestic properties and, if adopted throughout the industry, should lead to a more effective damage management service. This chapter specifically presents the assessment of a range of different flood damaged floors common in domestic properties. Eight scenarios are presented, followed by a discussion of the remedial solutions recommended by experts, including their perceived performance. First, the methodology used to collate the views of experts is presented, followed by the results of the data analysis and then a detailed discussion of the findings. For the benefit of readers who do not wish to go through these detailed findings, a summary of the results and implications of the findings are presented in the final section.

40

Reinstatement of Flood Damaged Floors

5.2

41

Methodology Respondents (see Appendix A for a detailed description of data collection) were first presented with digital photos taken from real footage of flooddamaged properties. They were then asked to indicate (with a tick) their present repair recommendation strategies for each flood damage scenario (i.e. each photograph). A list of commonly employed strategies was provided, enabling the respondents simply to tick their present strategy. These strategies were identified from literature review and in consultation with damage management experts, insurers and loss adjusters. Additionally, respondents were invited to add their own strategy if this was not listed. Respondents were then asked to assess the perceived performance of their present strategy in terms of (i) cost, (ii) quality, (iii) time and (iv) expected percentage of satisfied clients (called ‘satisfaction’ throughout this report for the purposes of brevity), on a five-point scale ranging from 1 to 5 (Table 5.1). Additionally, an overall performance measure was derived from the average of these performance criteria, allowing a comparison of overall performance between the strategies; this overall measure was considered to be the benchmark for each scenario. Before proceeding to the second question, respondents were asked whether their ideal repair strategies would be different from their present ones because it was anticipated that some respondents may be restricted in their current practice (e.g. because of employer restrictions). Respondents were required to indicate their ideal strategies with the option of adding to the list provided. Finally, to allow analysis of any differences between these present and ideal repair strategies, they were asked to rate the performance of their ideal strategies on the same five-point scale. Before conducting an analysis of the response, the information yielded was subjected to visual observation to acquire understanding of the dataset. Several respondents indicated multiple strategies for each scenario, and

Table 5.1

Likert scales used for the performance criteria Performance criteria

Level

Cost of repair works

Appropriateness of the repair

1 2 3 4 5

Very expensive Expensive Economically acceptable Inexpensive Very inexpensive

Very low Low Acceptable Good Very good

Time to conduct the repairs

Expected satisfied clients (%)

Very slow Slow Acceptable speed Fast Very fast

0–20 21–40 41–60 61–80 81–100

42

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some chose to add strategies to those provided. In these cases, the whole dataset was observed to ascertain the numbers of similar responses. Any new or existing strategies acquiring less than ten responses were excluded from the analysis as these were not considered common practice. Statistical tests were employed to investigate whether performance differences between strategies were significant.1 In this research, the average performance of two strategies was compared using the Mann–Whitney test. If the difference was significant at 1% or 5% levels, it could be concluded that the difference could also be found in the population of flood damage assessors with strong (99%) or some (95%) level of confidence, respectively. Two kinds of comparison were performed: the first was a comparison of the performance between strategies in each damage scenario, while the second was a comparison of the performance of present and ideal strategies. For the former, the comparison allowed the identification of an optimum strategy. For the latter, the comparison allowed understanding of the respondents’ intention to opt for another strategy (i.e. their ideal strategy). Comparisons were only made for those strategies which were chosen by at least ten respondents (as described earlier). To present the results of the statistical tests, matrices exhibiting relationships between various strategies were produced (see, for example, Table 5.3). Here, symbols of C, Q, T, S and O were used to indicate significant relationships in terms of cost, quality, time, expected percentage of satisfied clients and overall performance, respectively. Upper case symbols indicate 99% confidence levels, whilst lower case indicate 95% confidence levels.

5.3

Results and discussion The analysis of the flood damage scenarios is presented in this section. For each scenario, the digital image and the repair strategy options are first presented. Then, the respondents’ present strategies are presented and discussed, followed by a comparative analysis of the strategies. Preferences for ideal strategies are then presented and discussed. A comparison of the performance of these ideal strategies with that of current practice is then given. Deeper interpretations and/or implications of the findings are discussed in the summary (section 5.4).

1

That the performance of two strategies is significantly different means that there is a true difference in the sample as in the population. That is, the difference found in the analysis is not merely due to chances resulting from the sampling procedure, and therefore could be interpreted as being representative of the population with 95% or 99% confidence levels.

Reinstatement of Flood Damaged Floors

43

5.3.1 Flood damage scenario 1 The scenario was: ‘The dwelling has vinyl floor tiles installed that have been submerged by floodwater’ as presented in Figure 5.1. Two repair strategy options were provided as follows: Option 1: Recommend replacement of all floor tiles. Option 2: Recommend replacement of floor tiles that have become unbonded from the floor.

Figure 5.1

Image of flood damage scenario 1

Figure 5.2 presents the respondents’ present repair strategy choices. Most respondents (78.8%) selected option 1, i.e. the replacement of all floor tiles. In terms of quality, time, satisfaction, and as a whole, the performance of option 1 was better than option 2 as indicated in Figure 5.3. Statistical tests confirmed that the differences in performance were significant for cost, quality, satisfaction and overall performance. This infers that option 1 was significantly more costly, provided a higher level of quality and a higher proportion of satisfied clients than option 2. As shown in Figure 5.3, the difference in time performance was marginal. Results indicate that replacing all floor tiles would derive higher quality and satisfaction but at higher cost. Note that there was no perceived difference with regard to time performance between the two options. That is, the time taken to check and replace unbonded tiles would be the same as the time taken to replace all tiles. Overall, the performance of option 1 was significantly better than that of option 2, and hence provides the benchmark strategy for this scenario.

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Figure 5.2

Present repair strategies for flood damage scenario 1

Figure 5.3 scenario 1

Performance comparison between repair strategies of flood damage

Of the 265 experts who responded to this damage scenario, only 32 (12.1%) recommended an alternative ideal strategy (i.e. different to that presently used). Table 5.2 depicts a cross-tabulation of respondents who chose an alternative ideal repair strategy. The vast majority of these (30 respondents) currently employ option 2 but would prefer to use option 1. In contrast, only two who chose option 1 would prefer to use option 2. That is, most respondents who recommended an alternative ideal strategy would have preferred to have replaced all tiles as opposed to their present strategy of replacing those that had become unbonded. For those who chose an ideal strategy, Figure 5.4 shows a comparison of the performance for present (option 2) and ideal (option 1) strategies. The results indicate that the performance of the ideal strategy was significantly better (in terms of cost, quality, satisfaction and overall) to that of the current strategy. In summary, option 1 (replacement of

Reinstatement of Flood Damaged Floors

45

Table 5.2 Classification of respondents based on their present and ideal repair strategies for damage scenario 1 Ideal strategy Present strategy

Option 1

Option 1 Option 2

30 100.0%

Column total

30 93.8%

Option 2

Row total

2 100.0%

2 100.0% 30 100.0%

2 6.3%

32 100.0%

Note: Bold face indicates that the ‘quantity’ is sufficient for further statistical comparison (defined as at least 10).

Figure 5.4 Performance comparison between present (option 2) and ideal (option 1) repair strategies of flood damage scenario 1

all tiles) was the most popular solution which, although it was somewhat more costly, was found to provide a higher level of performance than option 2.

5.3.2 Flood damage scenario 2 The scenario was: ‘The dwelling has a vinyl sheet floor covering installed that has been submerged by floodwater’ as presented in Figure 5.5. Four alternative repair strategies provided were: Option 1: Recommend replacement of floor covering. Option 2: Recommend replacement of floor covering if it has been damaged by the floodwater.

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Option 3: Recommend the floor covering is carefully removed and cleaned and then re-laid. Option 4: Recommend the floor covering is cleaned in place.

Figure 5.5

Image of flood damage scenario 2

Figure 5.6 presents the respondents’ present repair strategies. Most respondents (65.1%) selected option 1, i.e. they recommended replacement of the floor covering. About a quarter (25.7%) recommended replacement of the floor covering only if it had been damaged by the floodwater. Very few selected options 3 (7.7%) or 4 (1.5%).

Figure 5.6

Present repair strategies for flood damage scenario 2

Reinstatement of Flood Damaged Floors

47

Figure 5.7 Performance comparison between repair strategies of flood damage scenario 2

Figure 5.7 presents a comparison of the performance of the different strategies in terms of cost, quality, time, satisfaction and overall. Option 4 was not included because it attracted so few responses. In general, option 1 performed better except in terms of cost, being the most costly strategy. The second most effective solution was option 2. The replacement of floor covering is therefore the benchmark strategy for this scenario. Table 5.3 presents the performance differences between the various repair strategies. A comparison between options 1 and 2 revealed significant differences in terms of quality, satisfaction and overall performance. A comparison between options 1 and 3 suggested significant differences in all performance aspects. A comparison between options 2 and 3 indicated significant differences in cost, time, satisfaction and overall performance. These findings could be used by flood damage assessors in determining which repair strategy is the most appropriate for a particular event. For example, an assessor may wish to Table 5.3 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 2 Repair strategy Option 1 Option 2

Option 2

Option 3

q,S,O

C,Q,T,S,O C,T,S,o

Note: Upper case indicates 99% confidence level; lower case indicates 95% confidence level. C or c, significant difference in cost performance; Q or q, significant difference in quality performance; T or t, significant difference in time performance; S or s, significant difference in expected percentage of satisfied clients; O or o, significant difference in overall performance.

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Table 5.4 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 2 Ideal strategy Present strategy

Option 1

Option 2

Option 1 Option 2 Option 3 Option 4 Column total

7 87.5% 4 50.0% 2 100.0%

4 50.0%

13 68.4%

4 21.1%

Option 3

Row total

1 100.0% 1 12.5%

1 100.0% 8 100.0% 8 100.0% 2 100.0%

2 10.5%

19 100.0%

consider options 1 or 2. Based on the analysis, the differences between options 1 and 2 are in their quality, satisfaction and overall performance, whereas in terms of cost and time, both options are very similar. Therefore, option 1 may be the most favourable because it delivers significantly better quality and satisfaction with relatively the same cost and time consumed. This is further confirmed by the overall performance, which indicates option 1 to be generally the most effective. Only 19 of the 268 respondents (7.1%) indicated an alternative ‘ideal’ strategy, as presented in Table 5.4. A comparison of the performance between present and ideal strategies was not conducted due to the small sample size in each case (i.e. less than ten in each cell of the matrix). However, most of these respondents (68.4%) indicated option 1 as their ideal strategy. None chose option 4 as their ideal strategy.

5.3.3 Flood damage scenario 3 The scenario was: ‘The dwelling has a quarry tiled floor which has been submerged by floodwater’ as presented in Figure 5.8. Four repair strategies were provided as follows: Option 1: Recommend replacement of floor tiles. Option 2: Recommend replacement of floor tiles if they have been damaged by the floodwater. Option 3: Recommend the floor tiles be carefully removed and cleaned and then re-laid. Option 4: Recommend the floor tiles be cleaned in place.

Reinstatement of Flood Damaged Floors

49

A reasonable number of respondents chose multiple strategies and therefore, one more option was established representing a combination of options 2 and 4. This was defined as: Option 5: Recommend the floor tiles be cleaned in place and replaced only where damaged by the floodwater (options 4 and 2).

Figure 5.8

Image of flood damage scenario 3

Figure 5.9 depicts current practice in dealing with this type of floor. The majority chose either options 2 (40.5%) or 4 (45.8%). Few selected options 1 (2.7%) and 3 (4.6%), while some (6.5%) chose a combination of options 2 and 4 (i.e. option 5). Figure 5.10 presents the performance of the strategies (option 1 was excluded because of the small sample size). Options 3 and 4 were the most costly and economic strategies, respectively. A similar tendency was found in time performance where option 4 was the quickest and option 3 the slowest. Option 3 provided the highest quality and satisfaction. Average performance (cost, quality, time and satisfaction) indicated that option 4 was the most effective, whilst option 3 was the least effective. Statistical tests (Table 5.5) confirmed the superiority of option 4 in cost, time and overall performance. In summary, cleaning is the benchmark strategy for this scenario. Fifty-one of the 263 respondents (19.4%) indicated an alternative ‘ideal’ strategy, as presented in Table 5.6. Here, option 1 was the most popular followed by option 3. Performance comparisons between present and ideal strategies were conducted for two cases, as presented in Figures 5.11 and 5.12.

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Chapter 5

Figure 5.9

Figure 5.10 scenario 3

Present repair strategies for flood damage scenario 3

Performance comparison between repair strategies of flood damage

Table 5.5 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 3 Repair strategy Option 2 Option 3 Option 4

Option 3

Option 4

c,s

C,T,O C,T,O

Note: See Table 5.3 for explanation of symbols.

Option 5

C,T,O

Reinstatement of Flood Damaged Floors

51

Table 5.6 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 3 Ideal strategy Present strategy Option 2 Option 3 Option 4 Option 5 Column total

Option 1 12 57.1% 1 100.0% 9 33.3% 1 50.0% 23 45.1%

Option 2

Option 3

Row total

9 42.9%

11 40.7%

7 25.9% 1 50.0%

21 100.0% 1 100.0% 27 100.0% 2 100.0%

11 21.6%

17 33.3%

51 100.0%

Note: See Table 5.2 regarding bold face numbers.

These revealed how these respondents rated the performance of both their present and ideal strategies. A comparison between options 2 (present) and 1 (ideal) revealed that option 1 was better in quality and satisfaction, whereas option 2 was better in cost and time. Statistical tests confirmed the differences in cost, quality and satisfaction; overall, option 1 was the most effective strategy, although the results were not statistically significant. A comparison between options 4 (present) and 2 (ideal) revealed that option 2 yielded higher quality and satisfaction, but was more costly and time consuming; overall,

Figure 5.11 Performance comparison between present (option 2) and ideal (option 1) repair strategies of flood damage scenario 3

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Figure 5.12 Performance comparison between present (option 4) and ideal (option 2) repair strategies of flood damage scenario 3

option 4 was the better strategy. All differences were statistically significant. These comparisons indicate that respondents who indicated an alternative ideal strategy desired better quality and higher satisfaction; however, in their present employment these strategies were prohibitively expensive and time consuming.

5.3.4 Flood damage scenario 4 The scenario was: ‘The dwelling has a solid concrete floor which has been submerged by floodwater’ as presented in Figure 5.13. Three alternative repair strategies provided were: Option 1: Recommend the floor screed be removed, the floor allowed to dry and then the screed replaced. Option 2: Recommend the floor be cleaned and allowed to dry. Option 3: Recommend the whole floor construction be replaced. Figure 5.14 presents the respondents’ present repair strategies. Most respondents (79.1%) chose option 2, i.e. they recommended the floor be cleaned and allowed to dry, but some (20.5%) chose option 1. Very few (0.4%) selected option 3, suggesting that replacing the whole floor construction is not a feasible strategy. Statistical tests confirmed significant differences in cost, quality and satisfaction (Figure 5.15). Here, option 2 was significantly cheaper while option 1 was superior in quality and satisfaction. Overall, there was no significant difference in the performance of options 1 and 2. Nevertheless,

Reinstatement of Flood Damaged Floors

Figure 5.13

Image of flood damage scenario 4

Figure 5.14

Present repair strategies for flood damage scenario 4

Figure 5.15

53

Performance comparison between repair strategies of flood damage scenario 4

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Chapter 5

Table 5.7 Classification of respondents based on their present and ideal repair strategies for damage scenario 4 Ideal strategy Present strategy

Option 1

Option 3

Row total

Option 2

45 90.0%

2 100.0% 5 10.0%

2 100.0% 50 100.0%

Column total

45 86.5%

7 13.5%

52 100.0%

Option 1

Note: See Table 5.2 regarding bold face numbers.

cleaning and allowing the floor to dry is the benchmark strategy for this scenario. Of the 268 practitioners who responded to this damage scenario, 52 (19.4%) recommended an alternative ideal strategy (i.e. different to that presently used). Table 5.7 presents a cross-tabulation of respondents who chose an alternative ideal repair strategy. Fifty respondents who selected option 2 would have preferred another option including 45 who preferred to employ option 1, and five who preferred option 3. Two respondents who chose option 1 would have preferred to recommend option 3. Figure 5.16 exhibits a comparison of the performance for present (option 2) and ideal (option 1) strategies. This indicates how they rated the performance of both their present and ideal strategies. Statistical tests indicated that option 2 was significantly better in terms of cost and time performance. However, option 1 was significantly better in terms of quality and satisfaction. Interest-

Figure 5.16 Performance comparison between present (option 2) and ideal (option 1) repair strategies of flood damage scenario 4

Reinstatement of Flood Damaged Floors

55

ingly, the difference in overall performance was very marginal, with higher quality and satisfaction (option 1) being balanced by cost efficiency and speed (option 2). This suggests that these respondents would prefer to adopt an alternative strategy which yields better quality and higher satisfaction. However, in their present employment this strategy was prohibitively expensive and time consuming.

5.3.5 Flood damage scenario 5 The scenario was: ‘The dwelling has a suspended timber (chipboard) floor which has been submerged by floodwater’ as presented in Figure 5.17. Five options of repair strategies provided were: Option 1: Recommend removal and replacement of all timber components (i.e. joists, floorboards, skirting, etc.). Option 2: Recommend replacement of chipboard. Option 3: Recommend replacement of only warped and rotten timber components. Option 4: Recommend removal of certain sections of chipboard so that drying can be aided. Option 5: Allow floor to dry and then assess replacement of timber components that have warped.

Figure 5.17

Image of flood damage scenario 5

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A reasonable number of respondents chose multiple strategies and therefore two more options were established. These were defined as follows: Option 6: Recommend replacement of chipboard and only warped and rotten timber components (options 2 and 3). Option 7: Recommend replacement of chipboard, allow floor to dry and then replace timber components that have warped (options 2 and 5). Figure 5.18 demonstrates the range of current practice in dealing with this type of damage. One-half of respondents chose option 2, while quite a considerable number selected options 1 (14.5%) and 5 (10.2%), and a few chose options 3 (7.4%), 4 (4.3%), 6 (5.4%) and 7 (8.2%). Evidently, the replacement of chipboard is considered an important aspect of this repair work. Figure 5.19 presents the performance of the various repair strategies. Option 5 was the most cost effective; option 1 provided highest quality and satisfaction, although its cost performance was the poorest. The results of statistical tests presented in Table 5.8 indicate that in terms of quality and satisfaction, option 1 was significantly better than options 2–5, although it was also significantly more costly than the other strategies. Option 6 yielded the best time performance and, most importantly, overall performance. In terms of time performance, option 6 was significantly better than options 4 and 5. Overall, option 6 was significantly better than options 3, 4 and 5. Overall, option 6 is therefore considered to be the most effective strategy. However, option 6 was selected by just a small number (5.4%) of respondents, possibly because it is a combination of options 2 and 3, and was not a standard option; this may therefore have influenced the number of respondents. In summary, the replacement of chipboard and only warped and rotten timber components (i.e. option 6) is the benchmark strategy for this scenario.

Figure 5.18

Present repair strategies for flood damage scenario 5

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Figure 5.19

57

Performance comparison between repair strategies of flood damage scenario 5

Fifty-two of the 272 respondents (19.1%) indicated an alternative ideal strategy to that of their present one, as presented in Table 5.9. A reasonable number of respondents who presently used option 2 would have preferred to adopt option 1 as their ideal strategy. A performance comparison between these two options is presented in Figure 5.20. This indicates how these respondents rated the performance of both their present and ideal strategies. Option 1 was significantly better than option 2 in terms of quality and satisfaction; however, option 2 was significantly better in cost performance. The difference in time and overall performance was not significant. These results suggest that those respondents who indicated an alternative strategy did so to improve quality and satisfaction, but with additional cost.

Table 5.8 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 5 Repair strategy

Option 2

Option 3

Option 4

Option 5

Option 6

Option 7

Option 1 Option 2 Option 3 Option 4 Option 5 Option 6

C,Q,S

C,Q,S,o C,Q,s

C,Q,S,o

C,Q,S,o C,Q,T,S,o

c

C

c,Q,S,O Q,t,O C,Q,t,S,O

C,Q,s,o q C,Q,S,o

Note: See Table 5.3 for explanation of symbols.

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Table 5.9 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 5 Ideal strategy Present strategy Option 1 Option 2 Option 3 Option 4 Option 5 Option 6 Option 1 Option 2 Option 3 Option 4 Option 5 Option 6 Column total

1 100.0% 3 12.5%

19 79.2% 5 55.6% 1 25.0% 7 53.8% 1 100.0%

3 33.3% 3 75.0% 4 30.8%

33 63.5%

10 19.2%

1 4.2% 1 11.1%

1 7.7%

4 7.7%

1 1.9%

1 4.2%

1 7.7%

2 3.8%

2 3.8%

Row total 1 100.0% 24 100.0% 9 100.0% 4 100.0% 13 100.0% 1 100.0% 52 100.0%

Note: See Table 5.2 regarding bold face numbers.

Figure 5.20 Performance comparison between present (option 2) and ideal (option 1) repair strategies of flood damage scenario 5

5.3.6 Flood damage scenario 6 The scenario was: ‘The dwelling has a suspended timber (chipboard) floor with tongued and grooved floorboards’ as presented in Figure 5.21. Five repair strategies were provided as follows:

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Figure 5.21

59

Image of flood damage scenario 6

Option 1: Recommend removal and replacement of all timber components (i.e. joists, floorboards, skirting, etc.). Option 2: Recommend replacement of all floorboards. Option 3: Recommend replacement of only warped and rotten timber components. Option 4: Recommend removal of certain floorboards so that drying can be aided. Option 5: Allow floor to dry and then assess replacement of timber components that have warped. A reasonable number of respondents selected multiple strategies and based on this, one more option was established representing a combination of options 4 and 5. This was defined as follows: Option 6: Recommend removal of certain floorboards so that drying can be aided, allow floor to dry and then replace timber components that have warped (options 4 and 5). Present repair strategies are depicted in Figure 5.22 and demonstrate a high level of disparity. Almost one-third of the respondents (32.1%) chose option 2, a quarter (22.1%) selected option 5, whilst quite a considerable number (16.7%) chose option 1; some respondents preferred options 3 (10.0%), 4 (8.8%) and 6 (10.4%) respectively. Figure 5.23 presents the performance of the strategies. The most economic strategy was option 5, while the most costly was option 1 (i.e. significantly

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Figure 5.22

Figure 5.23

Present repair strategies for flood damage scenario 6

Performance comparison between repair strategies of flood damage scenario 6

more costly than the other strategies; refer to Table 5.10). However, option 1 performed significantly better in terms of quality and satisfaction. There was no significant difference in time performance, suggesting that the time required to implement these strategies was perceived to be about the same. Overall, option 1 was considered the most effective, although this was not significant in most cases except in comparison between options 1 and 5 (option 1 being significantly better than option 5). Nevertheless, removal and replacement of all timber components (i.e. option 1) is the benchmark for this scenario.

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Table 5.10 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 6 Repair strategy

Option 2

Option 3

Option 4

Option 1 Option 2 Option 3 Option 4 Option 5

C,Q,S

C,Q,S c,s

C,Q,S c

Option 5

Option 6

C,Q,S,o C,Q,S

C,q,S c C,Q,s

Note: See Table 5.3 for explanation of symbols.

Table 5.11 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 6 Ideal strategy Present strategy

Option 1

Option 2

Option 1 Option 2 Option 3 Option 4 Option 5 Option 6 Column total

9 90.0% 4 50.0% 2 20.0% 9 64.3% 4 57.1%

3 37.5% 6 60.0% 5 35.7% 3 42.9%

28 53.8%

17 32.7%

Option 3

Option 5

1 33.3%

2 66.7% 1 10.0%

Option 6

1 12.5% 1 10.0%

1 10.0%

2 3.8%

4 7.7%

1 1.9%

Row total 3 100.0% 10 100.0% 8 100.0% 10 100.0% 14 100.0% 7 100.0% 52 100.0%

Of the 268 respondents, 52 (19.4%) indicated an alternative ideal strategy, as presented in Table 5.11; here, option 1 was favoured (refer to ‘column total’), suggesting a preference towards high quality but with additional expense. A comparison of the performance between present and ideal strategies was not conducted due to the small sample sizes involved.

5.3.7 Flood damage scenario 7 The scenario was: ‘When the floorboards are removed, it is discovered that the sleeper walls are constructed directly off the ground (i.e. no concrete slab has been included)’ as presented in Figure 5.24. Three options of repair strategies provided were:

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Option 1: Recommend that a concrete slab and damp proof membrane (dpm) be installed. Option 2: Recommend that a damp proof course (dpc) layer be installed into the present sleeper walls. Option 3: Recommend the sleeper walls be left alone.

Figure 5.24

Image of flood damage scenario 7

Figure 5.25 shows present repair strategies as indicated by the respondents. Almost half (48.7%) selected option 2, i.e. to recommend that a dpc be installed into the present sleeper walls; 35.9% favoured option 3 and 15.4% chose option 1. A comparison of the performance of these strategies (Figure 5.26) revealed that option 1 delivered the highest quality and satisfaction but was the most costly and time consuming strategy. Conversely, option 3 was

Figure 5.25

Present repair strategies for flood damage scenario 7

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Figure 5.26 scenario 7

63

Performance comparison between repair strategies of flood damage

the most economic and timely option but at the expense of quality and satisfaction. The performance of option 2 was intermediate between options 1 and 3. Overall, the performance differences between strategies were marginal, with option 2 being the best and option 1 the poorest. Statistical tests confirmed that the differences between option 1 and options 2 and 3 were significant in cost, quality, time and satisfaction (Table 5.12). The differences between options 2 and 3 were significant in cost, quality and satisfaction. There was no significant difference in overall performance, suggesting that there was very little to choose between the three strategies. Nonetheless, installing a dpc into the present sleeper walls is considered the benchmark strategy for this scenario. A high number (95) of the 247 respondents (38.5%) indicated an alternative ideal strategy, as presented in Table 5.13. Option 1 was most popular, whilst option 3 was ignored. The performance of present and ideal strategies was compared as presented in Figures 5.27–5.29. These indicate how these respondents rated the performance of both their present and ideal strategies. A comparison between option 2 (present) and option 1 (ideal) revealed that option 1 was superior in quality and satisfaction, whilst option 2 was better in Table 5.12 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 7 Repair strategy Option 1 Option 2

Option 2

Option 3

C,Q,T,S

C,Q,T,S C,Q,S

Note: See Table 5.3 for explanation of symbols.

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Table 5.13 Classification of respondents based on their present and ideal repair strategies for damage scenario 7 Ideal strategy Present strategy Option 2 Option 3 Column total

Option 1

Option 2

Row total

49 100.0% 28 60.9%

18 39.1%

49 100.0% 46 100.0%

77 81.1%

18 18.9%

95 100.0%

Note: See Table 5.2 regarding bold face numbers.

cost and time. Statistical tests confirmed these differences to be significant. Overall, option 2 was slightly better than option 1 although this was not statistically significant. A similar tendency was observed in comparison between option 3 (present) and option 1 (ideal). Here, the differences were even more disparate, with option 1 being slightly better than option 3 in overall performance. Again, a similar tendency was found in comparison between options 3 and 2. Option 2 was the better strategy in terms of quality and satisfaction, whilst option 3 was superior in cost and time performance. Overall, option 2 was slightly better than option 3. These findings suggest that these respondents would prefer to adopt alternative strategies which yield better quality and higher satisfaction. However, in their present employment these strategies were prohibitively expensive and time consuming.

Figure 5.27 Performance comparison between present (option 2) and ideal (option 1) repair strategies of flood damage scenario 7

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Figure 5.28 Performance comparison between present (option 3) and ideal (option 1) repair strategies of flood damage scenario 7

Figure 5.29 Performance comparison between present (option 3) and ideal (option 2) repair strategies of flood damage scenario 7

5.3.8 Flood damage scenario 8 The scenario was: ‘The dwelling has a concrete floor which has been covered with solid oak blocks’ as presented in Figure 5.30. Five repair strategies were provided as follows: Option 1: Replace all floor covering (i.e. the oak blocks). Option 2: Replace sections of blocks that have become unfixed from the concrete floor.

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Option 3: Lift all blocks, dry them and then replace them after the floor has dried. Option 4: Leave the floor alone. Option 5: Sand the floor and revarnish it. A reasonable number of respondents expressed another strategy and chose multiple strategies; therefore three more options were defined as follows: Option 6: Assess after the floor has dried. Option 7: Replace sections of blocks that have become unfixed from the concrete floor and sand the floor and revarnish it (options 2 and 5). Option 8: Lift all blocks, dry and replace them after the floor has dried and then sand the floor and revarnish it (options 3 and 5).

Figure 5.30

Image of flood damage scenario 8

Present repair strategies as indicated by respondents are presented in Figure 5.31. Of those who responded, 30.2% selected option 1, while options 2 and 3 were chosen by 20.0% and 19.6%, respectively. Few respondents indicated a preference to leave the floor alone (options 4 (3.1%) and 6 (3.9%) ). Some 11.0% of respondents favoured option 5, i.e. to sand the floor and revarnish it. Moreover, this option was also included in options 7 and 8 as a finishing process. Options 7 and 8 were selected by 8.2% and 3.9% of respondents, respectively. This indicates that a quite considerable number of respondents (11.0% þ 8.2% þ 3.9% ¼ 23.1%) recommended sanding and revarnishing the floor as an essential part of the repair work for this scenario.

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Figure 5.31

67

Present repair strategies for flood damage scenario 8

Figure 5.32 exhibits a comparison of the performance of the different strategies. Option 4 was excluded because of its small sample size. Option 5 was the most economic strategy, whilst option 1 was the most costly. Option 1 provided the highest quality and satisfaction, whilst option 5 yielded the poorest quality and satisfaction. This suggests the existence of mutual exclusivity between cost and quality/satisfaction. That is, any strategy which yields higher quality and/or satisfaction is more expensive (has poorer cost performance) and vice versa. Option 1 as the highest quality strategy was confirmed by statistical tests (Table 5.14). These findings were expected given the nature of the repair work involved, where major work (i.e. replacement of all floor covering) is required for option 1 and relatively minor work (sand the

Figure 5.32

Performance comparison between repair strategies of flood damage scenario 8

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Table 5.14 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 8 Repair strategy

Option 2

Option 3

Option 5

Option 6

Option 7

Option 8

Option 1 Option 2 Option 3 Option 5 Option 6 Option 7

C,Q,t,S

C,Q,S C,Q,T,S

C,Q,S

C,Q,S

C,q,S Q

C,q,S T

C,Q,t,S

c,s C,Q

t

Note: See Table 5.3 for explanation of symbols.

floor and revarnish it) for option 5. In terms of time taken, option 2 was the quickest whereas option 8 took the longest. Overall, option 1 was the most effective strategy, while option 8 was the poorest strategy. Statistical tests indicated that there was no significant difference in overall performance of the strategies. Nonetheless, the replacement of all floor covering (i.e. option 1) is the benchmark strategy for this scenario. Seventy-five out of the 261 respondents (28.7%) indicated an alternative ideal strategy. Table 5.15 presents a matrix showing the classification of Table 5.15 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 8 Ideal strategy Present strategy

Option 1 Option 2 Option 3 Option 5 Option 7 Option 8

Option 1 Option 2 Option 3 Option 4 Option 5

22 73.3% 13 100.0% 1 50.0% 11 68.8%

3 75.0% 7 23.3%

1 6.3%

Option 6 Option 7 Option 8 Column total

1 25.0% 1 3.3%

1 50.0% 4 25.0% 1 100.0%

6 85.7% 2 100.0% 55 73.3%

1 14.3%

1 1.3%

Note: See Table 5.2 regarding bold face numbers.

16 21.3%

1 1.3%

1 1.3%

1 1.3%

Row total 4 100.0% 30 100.0% 13 100.0% 2 100.0% 16 100.0% 1 100.0% 7 100.0% 2 100.0% 75 100.0%

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69

respondents based on their present and ideal repair strategies. Option 1 was the most popular ideal strategy suggesting an emphasis on high quality repair work; the second most popular strategy was option 3. Comparisons of performance were conducted on three cases as shown in Figures 5.33–5.35. These indicate how these respondents rated the performance of both their present and ideal strategies. A comparison between options 2 (present strategy) and 1 (ideal strategy) revealed that option 1 was better in quality and satisfaction, where as it was poorer in cost and time. These differences were confirmed by statistical tests. However, differences in overall performance were only marginal. A comparison between options 3 (present strategy) and 1 (ideal strategy)

Figure 5.33 Performance comparison between present (option 2) and ideal (option 1) repair strategies of flood damage scenario 8

Figure 5.34 Performance comparison between present (option 3) and ideal (option 1) repair strategies of flood damage scenario 8

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Figure 5.35 Performance comparison between present (option 5) and ideal (option 1) repair strategies of flood damage scenario 8

revealed that option 1 was better in quality, time and satisfaction, although the difference was not statistically significant for time performance. Option 1 was significantly more costly than option 3. Overall, option 1 was better as confirmed by statistical tests. A comparison between options 5 (present strategy) and 1 (ideal strategy) disclosed that option 1 was better in quality and satisfaction but poorer in cost, as confirmed by statistical tests. Option 5 was quicker, but not significantly so. Overall, option 1 was marginally better than option 5. These results suggest that respondents would prefer to adopt an alternative strategy which delivers higher quality and satisfaction. However, in their present employment such strategies were prohibitively expensive and time consuming.

5.4

Summary Tables 5.16–5.23 present a summary of the response to each scenario previously presented. Current strategies are listed in descending order of popularity and ranked in terms of their performance (cost, quality, time, satisfaction and overall performance). For each scenario, a benchmark is provided based on the overall performance. Implications arising from these results are also discussed.

5.4.1 Scenario 1: ‘The dwelling has vinyl floor tiles installed that have been submerged by floodwater’ A summary of the analysis for scenario 1 is provided in Table 5.16. Current practice as demonstrated by the majority of respondents (78.8%) is to

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71

Table 5.16 Summary of the analysis for scenario 1: ‘The dwelling has vinyl floor tiles installed that have been submerged by floodwater’ Performance ranking Repair strategy Replacement of all floor tiles Replacement of floor tiles that have become unbonded from the floor

Chosen by (%)

C

Q

T

S

O

78.8

2

1

1

1

1

21.2

1

2

2

2

2

Note: C, cost; Q, quality; T, time; S, satisfaction; O, overall performance.

recommend replacement of all tiles. This strategy yielded significantly higher levels of quality and satisfaction, and better overall performance. However, it was also considered to be somewhat costlier and was no faster than other strategies. Some respondents indicated a desire to employ an alternative strategy, which was prohibited in their present employment due to the increased costs involved. In conclusion, the replacement of all tiles is the benchmark strategy for this scenario. This solution, whilst more costly, was considered to be of high quality and deemed to deliver higher levels of satisfaction.

5.4.2 Scenario 2: ‘The dwelling has a vinyl sheet floor covering installed that has been submerged by floodwater’ A summary of the analysis for scenario 2 is provided in Table 5.17. Most respondents (65.1%) recommended the replacement of the floor covering which, although it was considered to be the most costly option, gave higher quality, satisfaction and overall performance; 25.7% recommended replacement of the floor covering only if it had been damaged by the floodwater, which was considered marginally more cost effective, but yielded lower levels of satisfaction. Very few recommended cleaning the floor covering only, suggesting that this was not a feasible strategy. Removing, cleaning Table 5.17 Summary of the analysis for scenario 2: ‘The dwelling has a vinyl sheet floor covering installed that has been submerged by floodwater’ Performance ranking Repair strategy Replacement of the floor covering Replacement of the floor covering if it has been damaged by the floodwater The floor covering is carefully removed and cleaned and then re-laid The floor covering is cleaned in place Note: See Table 5.16 for explanation of symbols.

Chosen by (%)

C

Q

T

S

O

65.1

3

1

1

1

1

25.7

2

2

2

2

2

7.7 1.5

1 –

3 –

3 –

3 –

3 –

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and re-laying the floor covering was the most cost effective strategy, although it was chosen by only a few respondents (7.7%). This suggests that cost is not the most important consideration for the repair of this flood damage scenario. In summary, replacement of the floor covering is the benchmark strategy for this scenario.

5.4.3 Scenario 3: ‘The dwelling has a quarry tiled floor which has been submerged by floodwater’ Table 5.18 presents a summary of the analysis for scenario 3. Most respondents recommended either cleaning the floor tiles in place (45.8%) or replacing the floor tiles if they had been damaged by the floodwater (40.5%). Some (6.5%) recommended a combination of both strategies. The cleaning strategy was less expensive and quicker, and yielded higher overall performance than the other strategies. Removal, cleaning and re-laying of the floor tiles yielded higher quality and satisfaction but poorer overall performance due to the costs involved and time required. All strategies yielded similar levels of quality and satisfaction. Here, then, choices could be made on the basis of time and cost. This suggests an advantage in employing the cleaning strategy. Replacement of the floor tiles was not commonly employed (2.7%). In summary, cleaning the floor tiles in place is the benchmark strategy for this scenario. Table 5.18 Summary of the analysis for scenario 3: ‘The dwelling has a quarry tiled floor which has been submerged by floodwater’ Performance ranking Repair strategy The floor tiles are cleaned in place Replacement of the floor tiles if they have been damaged by the floodwater The floor tiles are cleaned in place and replaced if they have been damaged by floodwater The floor tiles are carefully removed and cleaned and then relaid Floor tiles are replaced

Chosen by (%)

C

Q

T

S

O

45.8

1

4

1

2

1

40.5

3

3

2

4

3

6.5

2

2

3

3

2

4.6 2.7

4 –

1 –

4 –

1 –

4 –

Note: See Table 5.16 for explanation of symbols.

5.4.4 Scenario 4: ‘The dwelling has a solid concrete floor which has been submerged by floodwater’ Table 5.19 presents a summary of the analysis for scenario 4. Current practice as demonstrated by the majority (79.1%) of respondents is to recommend

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Table 5.19 Summary of the analysis for scenario 4: ‘The dwelling has a solid concrete floor which has been submerged by floodwater’ Performance ranking Repair strategy The floor is cleaned and allowed to dry The floor screed is removed, the floor allowed to dry and then the screed replaced The whole floor construction is replaced

Chosen by (%)

C

Q

T

S

O

79.1

1

2

1

2

1

20.5 0.4

2 –

1 –

2 –

1 –

2 –

Note: See Table 5.16 for explanation of symbols.

cleaning and allow the floor to dry; 20.5% of respondents suggested removing the floor screed, drying the floor, and replacing the screed. The latter procedure provided a better quality repair and higher satisfaction, but was more expensive. Although the former strategy was better in time taken and overall performance, these differences were marginal. These results suggest that replacement of the screed may be prohibitively expensive, despite this option providing better quality and higher satisfaction. This was further demonstrated by those indicating an ideal strategy, where replacement of screed was the most popular option chosen by 86.5% of those recommending an alternative ideal strategy. The ideal strategy was found to deliver better quality and satisfaction but to cost more and take longer. This suggests that levels of service could be improved beyond those presently provided, albeit with increased cost and time. In summary, cleaning and allowing the floor to dry is the benchmark solution for this scenario.

5.4.5 Scenario 5: ‘The dwelling has a suspended timber (chipboard) floor which has been submerged by floodwater’ A summary of the analysis for scenario 5 is presented in Table 5.20. The opinion of damage assessors was diverse regarding this scenario; however, 63.6% of the respondents recommended replacement of chipboard. Quite a considerable number of respondents (14.5%) recommended the removal and replacement of all timber components (i.e. joists, floorboards, skirting, etc.); 10.2% recommended drying the floor and then assessing the need to replace timber components that had warped. Drying the floor and then assessing the need to replace timber components that had warped was considered the most cost effective strategy. The removal and replacement of all timber components yielded the highest quality and satisfaction, but was the most expensive option. The replacement of chipboard and of only warped and rotten timber components (newly combined strategy) was best in terms of time and overall performance. However, this non-standard option was only

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Table 5.20 Summary of the analysis for scenario 5: ‘The dwelling has a suspended timber (chipboard) floor which has been submerged by floodwater’ Performance ranking Repair strategy Replacement of chipboard Removal and replacement of all timber components (i.e. joists, floorboards, skirting, etc.) Allow floor to dry and then assess replacement of timber components that have warped Recommend replacement of chipboard; allow floor to dry and then assess replacement of timber components that have warped Replacement of only warped and rotten timber components Replacement of chipboard and only warped and rotten timber components Removal of certain sections of chipboard so that drying can be aided

Chosen by (%)

C

Q

T

S

O

50.0

4

4

2

4

4

14.5

7

1

3

1

3

10.2

1

6

6

6

6

8.2

6

2

4

3

2

7.4

2

7

5

7

7

5.4

5

2

1

2

1

4.3

3

5

7

5

5

Note: See Table 5.16 for explanation of symbols.

selected by a minority of the respondents (5.4%). The most popular strategy, the replacement of chipboard, was not the most effective in any aspect of performance; however, neither was it the least effective strategy. This suggests an attempt by assessors when selecting an optimum repair strategy to balance quality and satisfaction expectations with the need to be cost effective and timely. The removal and replacement of all timber components was the most popular ideal repair strategy. Analysis of the performance differences between present and ideal repair strategies suggests that those respondents who indicated an alternative strategy did so to improve quality and satisfaction, but at additional cost. In summary, the replacement of chipboard and of only warped and rotten timber components is the benchmark strategy for this scenario.

5.4.6 Scenario 6: ‘The dwelling has a suspended timber (chipboard) floor with tongued and grooved floorboards’ A summary of the analysis for scenario 6 is presented in Table 5.21. There was no consensus regarding present repair strategies for this scenario: 32.1% of respondents recommended the replacement of all floorboards, and

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75

Table 5.21 Summary of the analysis for scenario 6: ‘The dwelling has a suspended timber (chipboard) floor with tongued and grooved floorboards’ Performance ranking Repair strategy Replacement of all floorboards Allow floor to dry and then assess replacement of timber components that have warped Removal and replacement of all timber components (joists, floorboards, skirting, etc.) Removal of certain floorboards so that drying can be aided and allow floor to dry and then assess replacement of timber components that have warped Replacement of only warped and rotten timber components Removal of certain floorboards so that drying can be aided

Chosen by (%)

C

Q

T

S

O

32.1

4

3

2

2

2

22.1

1

6

6

6

5

16.7

6

1

3

1

1

10.4

5

2

4

3

4

10.0

3

4

4

5

6

8.8

2

5

1

4

3

Note: See Table 5.16 for explanation of symbols.

22.1% recommended drying the floor and then assessing the replacement of timber components that had warped. Quite a considerable number (16.7%) advocated the removal and replacement of all timber components (joists, floorboards, skirting, etc.), which provided highest quality and satisfaction but at highest cost. Drying the floor and then assessing the replacement of timber components that had warped was considered the most cost effective strategy. There was no significant difference in time performance among the strategies. Overall, the removal and replacement of all timber components was considered the most effective option, although differences from other strategies were marginal. The performance of the most popular strategy, the replacement of all floorboards, was neither the most nor the least effective option in all performance aspects. This suggests respondents tried to balance the requirements of quality and satisfaction with those of cost and time in selecting an optimum repair strategy. Being the most popular alternative ideal strategy, removal and replacement of all timber components, although more costly, yielded a high quality repair and was deemed to give higher satisfaction levels. This suggests that the respondents would prefer to adopt a strategy that delivers higher quality and greater satisfaction, but such a strategy is presently prohibitively expensive. In summary, removal and replacement of all timber components is the benchmark strategy for this scenario.

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5.4.7 Scenario 7: ‘When the floorboards are removed, it is discovered that the sleeper walls are constructed directly off the ground (i.e. no concrete slab has been included)’ A summary of the analysis results for scenario 7 is presented in Table 5.22. The opinion of damage assessors was diverse regarding this scenario: 48.7% of the respondents recommended that a damp proof course (dpc) be installed in the present sleeper walls; however, 35.9% recommended that the sleeper walls should be left alone. Some (15.4%) recommended that a concrete slab and damp proof membrane (dpm) be installed. Installing a concrete slab and a dpm delivered the highest quality and satisfaction, but was considered the most costly and time consuming strategy. As expected, leaving the sleeper walls alone was the quickest and most inexpensive strategy but quality and satisfaction were lower. The performance of installing a dpc into the present sleeper walls (i.e. most popular strategy) was intermediate between the other two strategies in terms of cost, quality, time and satisfaction. These findings suggest that some strategies which are known to provide higher levels of quality and satisfaction may be prohibitively expensive. Overall, installing a dpc into the present sleeper walls was the most effective strategy whilst installing a concrete slab and dpm was the poorest; however, these results were not confirmed statistically. A high number of respondents (40.5%) would consider strategies different from their present ones. Here, installing a concrete slab and dpm was the most popular (as favoured by 81.1% of those who indicated an ideal strategy). Ideal strategies provided better quality repairs and higher satisfaction, while present strategies were cheaper and quicker to implement. Differences in overall performance were found to be marginal. This indicates that assessors would prefer to adopt strategies that deliver higher quality and satisfaction, but these are presently prohibitively expensive and time consuming. In sum, installing a dpc into the present sleeper walls is the benchmark solution for this scenario.

Table 5.22 Summary of the analysis for scenario 7: ‘When the floorboards are removed, it is discovered that the sleeper walls are constructed directly on the ground (i.e. no concrete slab has been included)’ Performance ranking Repair strategy A dpc is installed in the present sleeper walls The sleeper walls are left alone A concrete slab and dpm are installed Note: See Table 5.16 for explanation of symbols.

Chosen by (%)

C

Q

T

S

O

48.7 35.9 15.4

2 1 3

2 3 1

2 1 3

2 3 1

1 2 3

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Table 5.23 Summary of the analysis for scenario 8: ‘The dwelling has a concrete floor which has been covered with solid oak blocks’ Performance ranking Repair strategy Replace all floor covering (i.e. the oak blocks) Replace sections of blocks that have become unfixed from the concrete floor Lift all blocks, dry them and then replace them after the floor has dried Sand the floor and revarnish it Replace sections of blocks that have become unfixed from the concrete floor and sand the floor and revarnish it Assess when the floor has dried Lift all blocks, dry and replace them after the floor has dried and then sand the floor and revarnish it Leave the floor alone

Chosen by (%)

C

Q

T

S

O

30.2

7

1

4

1

1

20.0

2

6

1

6

4

19.6 11.0

6 1

3 7

6 2

2 7

5 3

8.2 3.9

5 3

2 5

3 5

3 4

2 6

3.9 3.1

3 –

4 –

7 –

4 –

7 –

5.4.8 Scenario 8: ‘The dwelling has a concrete floor which has been covered with solid oak blocks’ A summary of the analysis for scenario 8 is presented in Table 5.23; there was no consensus regarding present repair strategies. A significant proportion of the respondents (30.2%) recommended the replacement of all the floor covering (i.e. the oak blocks), whereas 20.0% recommended the replacement of sections of blocks that had become unfixed from the concrete floor and a similar proportion (19.6%) recommended lifting all blocks, drying them and then replacing them when the floor had dried. Some (11.0%) advocated sanding and revarnishing the floor. The replacement of all the floor covering provided the highest quality and satisfaction, but was considered the most costly strategy. Sanding and revarnishing the floor was the most economic strategy to be implemented, but it yielded the poorest quality and satisfaction. The replacement of sections of blocks that had become unfixed from the concrete floor was the quickest strategy to be implemented. Overall, the replacement of all the floor covering was the best strategy. Differences in overall performance between strategies were marginal. For those respondents (29.9%) who indicated alternative ideal strategies, the most favoured option (as chosen by 73.3%) was replacement of all the floor covering. Generally, this ideal strategy provided better quality and higher satisfaction, but at higher cost. In summary, the replacement of all the floor covering is the benchmark strategy for this scenario. The next chapter will discuss the reinstatement of flood damaged walls.

6

6.1

Reinstatement of Flood Damaged Walls Introduction This chapter presents the assessment of a range of different flood damaged walls commonly found in domestic properties. Fourteen scenarios are presented, followed by a discussion of the remedial solutions indicated by the respondents, including their perceived performance. First, the results and analysis are presented, followed by a detailed discussion of the findings. Finally, a summary is presented together with a discussion of the implications arising from these findings.

6.2

Results and discussion For each scenario, the digital image and the repair strategy options are first presented. Then, the respondents’ present strategies are presented and discussed, followed by a comparative analysis of the strategies. Preferences for ideal strategies are then presented and discussed. A comparison of the performance of these ideal strategies with that of current practice is then given.

6.2.1 Flood damage scenario 9 The scenario was: ‘The external wall of the property is brickwork with cement mortar joints’ as presented in Figure 6.1. Five repair strategies were provided as follows: Option 1: Option 2: Option 3: Option 4: Option 5:

Recommend the wall be cleaned. Recommend the wall be cleaned and repainted. Recommend the wall be sandblasted to remove any flood debris. Recommend the wall be left alone. Recommend the wall be demolished and reconstructed.

Present repair strategies of the experts are presented in Figure 6.2. Some 48.7% of respondents chose option 1, i.e. they recommended the wall be cleaned, whereas 36.2% recommended the wall be cleaned and repainted (option 2). Some selected options 3 (7.9%) and 4 (7.2%). No respondent recommended

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Figure 6.1

Image of flood damage scenario 9

Figure 6.2

Present repair strategies for flood damage scenario 9

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option 5, suggesting that demolishing and reconstructing the wall is not a viable strategy in these circumstances. A comparison of the performance of the strategies is presented in Figure 6.3. Option 1 was considered to be the most cost effective strategy, whilst option 3 was the most costly. Surprisingly, option 1 also yielded the best quality repair, although this difference was not significant (Table 6.1). As expected, option 4 was the quickest, followed closely by option 1. Option 3 gave the highest satisfaction among strategies. Overall, option 1 was considered the most effective strategy and is the benchmark strategy for this scenario. Of the 267 experts who responded to this damage scenario, only 34 (12.7%) would recommend an alternative ideal strategy (i.e. different to that presently used), as presented in Table 6.2. Option 3 was the most popular strategy and

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Figure 6.3 scenario 9

Performance comparison between repair strategies of flood damage

Table 6.1 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 9 Repair strategy Option 1 Option 2 Option 3

Option 2

Option 3

Option 4

C,T,O

C,t,O

S C,t,S c,S

Note: Upper case indicates 99% confidence level; lower case indicates 95% confidence level. C or c, significant difference in cost performance; Q or q, significant difference in quality performance; T or t, significant difference in time performance; S or s, significant difference in expected percentage of satisfied clients; O or o, significant difference in overall performance.

Table 6.2 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 9 Ideal strategy Present strategy

Option 1

Option 1

Option 2

Option 3

9 50.0%

9 50.0% 11 91.7%

1 8.3%

20 58.8%

1 2.9%

Option 2 Option 3 Option 4

1 50.0%

2 100.0% 1 50.0%

Column total

1 2.9%

12 35.3%

Option 5

Row total 18 100.0% 12 100.0% 2 100.0% 2 100.0% 34 100.0%

Note: Bold face indicates that the ‘quantity’ is sufficient for further statistical comparison (defined as at least 10).

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Figure 6.4 Performance comparison between present (option 2) and ideal (option 3) repair strategies of flood damage scenario 9

option 2 the second most popular. A performance comparison between present and ideal strategies is presented in Figure 6.4. Option 3 was significantly better than option 2 in quality and satisfaction, whereas option 2 was significantly better in cost performance. In terms of time performance, both strategies were considered to be about the same. Overall, option 3 was the better strategy, although this difference was not statistically significant. These results suggest that respondents would have preferred to adopt a strategy which yielded better quality and satisfaction; however, in their current employment this was prohibitively expensive.

6.2.2 Flood damage scenario 10 The scenario was: ‘The external wall of the property has a rendered finish’ as presented in Figure 6.5. Seven repair strategies were provided as follows: Option 1: Option 2: Option 3: Option 4: Option 5: Option 6: Option 7:

Recommend the render be cleaned. Recommend the wall be sandblasted to remove any flood debris. Recommend the wall be left alone. Recommend the wall be demolished and reconstructed. Recommend all the render be removed and replaced. Recommend areas of the render that have spalled be replaced. Recommend areas of the render that have become unbonded from the wall substrate be replaced.

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Figure 6.5

Image of flood damage scenario 10

A reasonable number of respondents chose multiple strategies; therefore, three more options were established, representing combinations of the above options. These were defined as follows: Option 8:

Option 9: Option 10:

Recommend the render be cleaned and then areas of the render that have become unbonded from the wall substrate be replaced (options 1 and 7). Recommend areas of the render that have spalled and become unbonded from the wall substrate be replaced (options 6 and 7). Recommend the render be cleaned first, and then areas of the render that have spalled and become unbonded from the wall substrate be replaced (options 1, 6 and 7).

Present repair strategies are presented in Figure 6.6. There was no single dominant strategy, the most popular being options 1 (25.4%) and 7 (32.8%). Some respondents (10.2%) chose option 6 and almost equal numbers recommended options 8 (8.6%), 9 (7.8%) and 10 (7.8%). Options 2 (1.2%), 3 (2.3%) and 5 (3.9%) were not commonly used. Option 4 was not chosen by any respondents, indicating that demolishing and reconstructing the wall is not a viable strategy in these circumstances. Figure 6.7 depicts a comparison of the performance of the repair strategies. Options 2 and 3 were not compared because of their small sample sizes. Option 1 was the most cost effective strategy, and option 5 was the most costly. Option 10 resulted in the highest quality repair, closely followed by option 5. Options 7 and 9 yielded the poorest quality repairs. Surprisingly, option 1 was not the poorest, despite the relatively simple work involved (i.e. just cleaning). Option

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Figure 6.6

Figure 6.7

83

Present repair strategies for flood damage scenario 10

Performance comparison between repair strategies of flood damage scenario 10

1 was the quickest strategy. Option 5 delivered the highest level of client satisfaction. To confirm the significance or otherwise of these performance differences, statistical tests were conducted, as presented in Table 6.3. There were no significant differences in all performance aspects between options 6, 7, 8 and 9, suggesting that selection of any of these strategies will result in a similar performance outcome. Overall, option 1 was the most effective solution and hence provides the benchmark for this scenario. Forty-three out of the 263 respondents (16.3%) would consider different strategies than their present ones, as presented in Table 6.4. A comparison of

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Table 6.3 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 10 Repair strategy

Option 1 Option 5 Option 6 Option 7 Option 8 Option 9 Option 10

Option 1 Option 5 Option 6 Option 7 Option 8 Option 9 Option 10

C,S

C,o S

C,T,O c,S

C c

C C

C,q,T,s c s Q t q

Note: See Table 6.1 for explanation of symbols.

Table 6.4 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 10 Ideal strategy Present strategy

Option 1

Option 1

Option 2

Option 5

Option 6

Option 7

Row total

1 7.7%

5 38.5%

1 7.7% 1 100.0% 1 50.0%

6 46.2%

1 20.0%

2 40.0% 16 100.0% 3 75.0% 2 100.0%

13 100.0% 1 100.0% 2 100.0% 5 100.0% 16 100.0% 4 100.0% 2 100.0%

Option 2 Option 3

1 50.0%

Option 6 Option 7 Option 9 Option 10 Column total

1 2.3%

2 4.7%

28 65.1%

2 40.0%

1 25.0%

3 7.0%

9 20.9%

43 100.0%

the performance between present and ideal strategies was conducted only for one case (present option 7 and ideal option 5). None considered options 3 and 4 as ideal strategies. Figure 6.8 provides a performance comparison between present (option 7) and ideal (option 5) strategies. The results suggest that performance was significantly different in terms of cost, quality, satisfaction and overall, while time performance was not different. Option 5, being more costly, gives a higher quality repair, a larger proportion of satisfied clients and better overall performance than option 7.

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Figure 6.8 Performance comparison between present (option 7) and ideal (option 5) repair strategies of flood damage scenario 10

6.2.3 Flood damage scenario 11 The scenario was: ‘The external wall of the property has a pebbledash finish’ as presented in Figure 6.9. Seven repair strategies were provided as follows: Option 1: Option 2: Option 3: Option 4: Option 5: Option 6:

Recommend the pebbledash render be cleaned. Recommend the wall be sandblasted to remove any flood debris. Recommend the wall be left alone. Recommend the wall be demolished and reconstructed. Recommend all the pebbledash render be removed and replaced. Recommend areas of the pebbledash render that have spalled be replaced. Option 7: Recommend areas of the pebbledash render that have become unbonded from the wall substrate be replaced. A reasonable number of respondents chose multiple strategies; therefore, three more options were established, representing combinations of the above options. These were defined as follows: Option 8: Recommend the pebbledash render be cleaned and then areas of the render that have become unbonded from the wall substrate be replaced (options 1 and 7). Option 9: Recommend areas of the pebbledash render that have spalled and become unbonded from the wall substrate be replaced (options 6 and 7).

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Option 10:

Figure 6.9

Recommend the pebbledash render be cleaned first, and then areas of the render that have spalled and become unbonded from the wall substrate be replaced (options 1, 6 and 7).

Image of flood damage scenario 11

The respondents’ present repair strategies are presented in Figure 6.10. A majority recommended either options 1 (27.3%) or 7 (30.4%). Some chose options 6 (10.7%), 8 (7.5%), 9 (7.9%) and 10 (8.7%). Few selected options 2 (1.2%), 3 (3.2%) and 5 (3.2%). None selected option 4, suggesting that demolishing and reconstructing the wall is not a viable strategy in these circumstances. The performance comparisons between strategies are presented in

Figure 6.10

Present repair strategies for flood damage scenario 11

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Figure 6.11

87

Performance comparison between repair strategies of flood damage scenario 11

Figure 6.11. The performance of options 2, 3 and 5 was not compared due to the small sample size. Option 1 was the most cost effective strategy as confirmed by statistical tests (Table 6.5) and option 10 delivered higher quality. Option 1 was considered the quickest strategy to be implemented, whereas option 10 was the most time consuming. Option 9 yielded higher levels of satisfaction. Overall, option 1 was the most effective strategy, and is the benchmark strategy for this scenario. It is interesting to note that there were no significant differences in all performance aspects between options 6, 7, 8 and 9, suggesting that the selection of any of these strategies will result in a similar performance outcome. Fifty of the 266 respondents (18.8%) would consider different strategies than their present ones, as presented in Table 6.6. Option 5 was the most popular ideal strategy. A comparison of performance was conducted only for one case, as shown in Figure 6.12. Although option 5 was the more Table 6.5 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 11 Repair strategy Option 1 Option 6 Option 7 Option 8 Option 9

Option 6

Option 7

Option 8

Option 9

Option 10

C,o

C,T,O

C

C,s

C,q,T,s q,o q,s,o

Note: See Table 6.1 for explanation of symbols.

q

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Table 6.6 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 11 Ideal strategy Present strategy Option 1

Option 2

Option 5

Option 6

Option 7

Option 9

Row total

2 10.5%

5 26.3% 1 100.0%

3 15.8%

8 42.1%

1 5.3%

19 100.0% 1 100.0% 1 100.0% 5 100.0% 17 100.0% 1 100.0% 4 100.0% 2 100.0%

1 2.0%

50 100.0%

Option 2 Option 3 Option 6 Option 7

1 5.9%

Option 8 Option 9 Option 10 Column total

3 6.0%

1 100.0% 2 40.0%

3 60.0% 16 94.1% 1 100.0% 4 100.0% 2 100.0% 32 64.0%

3 6.0%

11 22.0%

Note: See Table 6.2 regarding bold face numbers.

Figure 6.12 Performance comparison between present (option 7) and ideal (option 5) repair strategies of flood damage scenario 11

costly and slower strategy, it yielded higher quality and satisfaction. Statistical tests confirmed the differences in cost, time and satisfaction. Overall, both options performed almost the same. The results suggest that these respondents would prefer to adopt an alternative strategy which gave higher

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89

satisfaction; however, in their present employment, this strategy was prohibitively expensive and time consuming.

6.2.4 Flood damage scenario 12 The scenario was: ‘An internal wall of the flood damaged property is constructed of brickwork with a paint finish applied directly to it’ as presented in Figure 6.13. Five alternative repair strategies were provided as follows: Option 1: Option 2: Option 3: Option 4: Option 5:

Figure 6.13

Recommend the wall be repainted. Recommend the wall be sandblasted to remove any germs. Recommend the wall be repointed. Recommend the wall be cleaned and repainted. Recommend the wall be cleaned, plastered and decorated.

Image of flood damage scenario 12

The respondents’ present repair strategies are presented in Figure 6.14. Most recommended option 4 (86.0%), while the other strategies were less favoured including options 1 (4.0%), 2 (5.2%), 3 (1.2%) and 5 (3.6%). A comparison of the performance between options 2 and 4 is presented in Figure 6.15. The other options were not compared due to their small sample sizes. The results indicate that option 4 was better in all aspects of performance although the differences were not statistically significant. Nevertheless, cleaning and repainting the wall is the benchmark solution for this scenario.

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Figure 6.14

Present repair strategies for flood damage scenario 12

Figure 6.15 scenario 12

Performance comparison between repair strategies of flood damage

Of the 267 respondents who responded to this damage scenario, only 23 (8.6%) recommended an alternative ideal strategy (i.e. different to that presently used). Table 6.7 depicts a cross-tabulation of respondents who chose an alternative ideal repair strategy. Option 5 was the most popular ideal strategy. A comparison between options 4 (present strategy) and 5 (ideal strategy) is presented in Figure 6.16. Option 5 produced significantly better quality and satisfaction, whereas option 4 was more cost effective and quicker to implement. Differences in all but time performance were confirmed by statistical tests. This suggests that these respondents would prefer to adopt an alternative strategy which gave better quality and higher satisfaction. However, in their present employment this strategy was prohibitively expensive. Overall, the performance difference was only marginal.

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Table 6.7 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 12 Ideal strategy Present strategy

Option 2

Option 2 Option 3 Option 4 Option 5 Column total

Option 4

Option 5

Row total

1 50.0% 1 100.0%

1 50.0%

2 100.0% 1 100.0% 19 100.0% 1 100.0%

4 21.1% 1 100.0% 5 21.7%

15 78.9%

2 8.7%

16 69.6%

23 100.0%

Note: See Table 6.2 regarding bold face numbers.

Figure 6.16 Performance comparison between present (option 4) and ideal (option 5) repair strategies of flood damage scenario 12

6.2.5 Flood damage scenario 13 The scenario was: ‘An internal wall of the flood damaged property has been covered with ceramic tiles’ as presented in Figure 6.17. Three repair strategy options were provided as follows: Option 1: Recommend the wall be left alone. Option 2: Recommend that only ‘loose’ tiles be replaced. Option 3: Recommend all tiles be replaced.

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Figure 6.17

Image of flood damage scenario 13

Figure 6.18 shows the respondents’ present repair strategy choices. The majority of respondents (53.9%) recommended option 3, that is to replace all tiles, whereas 41.8% chose option 2 and only a few (4.3%) selected option 1. A comparison of the performance of these strategies is presented in Figure 6.19. Surprisingly, option 2 was considered the most cost effective strategy, where option 1 was ideally the most cost effective one. As expected, option 3 yielded highest quality and satisfaction. Option 1 was considered the most timely strategy. Statistical tests (Table 6.8) revealed that there are no performance differences between options 1 and 2. This suggests that replacing only ‘loose’ tiles achieves similar performance as leaving the wall alone. It is also interesting to note that there was no significant difference in time performance between options 2 and 3, suggesting that the time required to replace all

Figure 6.18

Present repair strategies for flood damage scenario 13

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Figure 6.19

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Performance comparison between repair strategies of flood damage scenario 13 Table 6.8 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 13 Repair strategy

Option 2

Option 3

Option 1 Option 2

c,Q,t,S C,Q,S,O

Note: See Table 6.1 for explanation of symbols.

Table 6.9 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 13 Ideal strategy Present strategy

Option 2

Option 3

Row total

2 100.0% 54 100.0%

2 100.0% 54 100.0% 1 100.0%

56 98.2%

57 100.0%

Option 1 Option 2 Option 3 Column total

1 100.0% 1 1.8%

Note: See Table 6.2 regarding bold face numbers.

tiles is the same as the time required to replace just the ‘loose’ tiles. Overall, option 3 was the most effective strategy and is the benchmark strategy for this scenario. Fifty-seven of the 270 respondents (21.1%) would consider strategies different to their present ones, as presented in Table 6.9. Option 3 was the most

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Figure 6.20 Performance comparison between present (option 2) and ideal (option 3) repair strategies of flood damage scenario 13

popular ideal strategy accounted for almost all ideal strategies selected. A comparison of the performance between options 2 (present strategy) and 3 (ideal strategy) is presented in Figure 6.20. Option 3 was better in terms of quality and satisfaction, whereas option 2 was better in terms of cost and time. Overall, option 3 was better than option 2. All differences were statistically confirmed. This suggests that these respondents would prefer to adopt an alternative strategy which yielded better quality and higher satisfaction; however, in their present employment, this strategy was prohibitively expensive and time consuming. The overall performance of the ideal strategy was better than that presently used.

6.2.6 Flood damage scenario 14 The scenario was: ‘An internal wall of the flood damaged property has been covered with a wood veneer on timber grounds’ as presented in Figure 6.21. Three repair strategy options were provided as follows: Option 1: Recommend the wood veneer be cleaned. Option 2: Recommend the veneer in contact with floodwater be replaced. Option 3: Recommend the veneer be replaced. The respondents’ present repair strategies are presented in Figure 6.22. A majority of respondents (70.8%) recommended option 3, that is to replace the veneer, whereas 25.5% chose option 2 and only a few (3.7%) selected

Reinstatement of Flood Damaged Walls

Figure 6.21

Image of flood damage scenario 14

Figure 6.22

Present repair strategies for flood damage scenario 14

95

option 1. A comparison of the performance of the strategies is presented in Figure 6.23. Option 1 was the most cost effective strategy, whilst option 3 provided highest quality and satisfaction. All differences were statistically confirmed (Table 6.10). Moreover, option 3 was also considered the quickest strategy to implement, although the difference was not statistically significant (Table 6.10); thus the time required to implement these three strategies was approximately the same. Overall, option 3 was the most effective strategy, which although costly, provided higher quality and satisfaction, and was somewhat quicker to implement than the alternative strategies. Thus, the replacement of the wood veneer is the benchmark for this scenario. Of the 271 respondents who responded to this damage scenario, only 28 (10.3%) recommended an alternative ideal strategy (i.e. different to that

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Figure 6.23 scenario 14

Performance comparison between repair strategies of flood damage

Table 6.10 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 14 Repair strategy

Option 2

Option 3

C

C,Q,S C,Q,S,O

Option 1 Option 2

Note: See Table 6.1 for explanation of symbols.

Table 6.11 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 14 Ideal strategy Present strategy Option 1

Option 2

Option 3

Row total

2 50.0%

2 50.0% 23 100.0%

4 100.0% 23 100.0% 1 100.0%

25 89.3%

28 100.0%

Option 2 Option 3

1 100.0%

Column total

3 10.7%

Note: See Table 6.2 regarding bold face numbers.

presently used) as presented in Table 6.11. Option 3 was the most popular strategy. A comparison of performance was conducted between option 2 (present strategy) and option 3 (ideal strategy) as depicted in Figure 6.24. Option 3 was superior in quality and satisfaction, whereas option 2 was better

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Figure 6.24 Performance comparison between present (option 2) and ideal (option 3) repair strategies of flood damage scenario 14

in cost and time performance. Overall, option 3 was the better strategy. All differences except time performance were statistically confirmed. This indicates that these respondents would prefer an ideal strategy which gave better quality and higher satisfaction; however, this strategy was prohibitive in their current employment due to the increased costs involved.

6.2.7 Flood damage scenario 15 The scenario was: ‘An internal wall of the flood damaged property has been decorated with wallpaper’ as presented in Figure 6.25. Two repair strategy options were provided as follows: Option 1: Recommend all wallpaper be replaced. Option 2: Recommend that only flood damaged wallpaper be replaced. Figure 6.26 depicts the respondents’ present repair strategy choices. Almost all the respondents (95.9%) recommended option 1, that is replacing all the wallpaper; few (4.1%) chose option 2. A comparison of the performance between these two strategies is shown in Figure 6.27. Option 1 was better in all aspects of performance except in cost. All differences except time performance were statistically confirmed. The benchmark strategy for this scenario is the replacement of all wallpaper (i.e. option 1). Only six out of the 270 respondents (2.2%) would consider different strategies than their present ones, as presented in Table 6.12. A comparison

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Figure 6.25 Image of flood damage scenario 15

Figure 6.26 Present repair strategies for flood damage scenario 15

Figure 6.27 15

Performance comparison between repair strategies of flood damage scenario

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Table 6.12 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 15 Ideal strategy Present strategy

Option 1

Option 1 Option 2

4 100.0%

Column total

4 66.7%

Option 2

Row total

2 100.0%

2 100.0% 4 100.0%

2 33.3%

6 100.0%

of the performance between present and ideal strategies was not conducted due to the small sample size in each case (i.e. less than ten in each cell of the matrix).

6.2.8 Flood damage scenario 16 The scenario was: ‘An external wall of a flood damaged property has evidence of a rising damp problem’ as presented in Figure 6.28. Five repair strategy options were provided as follows: Option 1: Recommend the wall be injected with a damp proof course (dpc) and the plaster replaced. Option 2: Recommend the client be approached to pay for curing the rising damp problem and the plaster be replaced. Option 3: Recommend the plaster be replaced with cement/sand render and skimmed with gypsum. Option 4: Recommend the wall be patched up. Option 5: Recommend the wall be repainted after it has dried. Figure 6.29 shows the respondents’ present repair strategies. A majority (76.4%) recommended option 2; some (15.8%) selected option 1 and a few recommended options 3 (4.1%), 4 (0.4%) and 5 (3.3%). Figure 6.30 presents a comparison of the performance of the strategies. Option 2 emerged as the most cost effective strategy; however, in terms of quality, satisfaction and overall performance it was the poorest. Option 1 performed better in quality, time, satisfaction as well as overall performance. It is worth noting that although option 2 was recommended by a majority of respondents, it has the poorest overall performance due to the lower satisfaction level. The results

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Figure 6.28

Image of flood damage scenario 16

Figure 6.29

Present repair strategies for flood damage scenario 16

of statistical tests (Table 6.13) revealed there was no significant difference between options 1 and 3, suggesting that these options were perceived to have a similar influence on the outcome of the repair works. Nevertheless, injecting the wall with a dpc and replacing the plaster (i.e. option 1) is the benchmark solution for the scenario. Fifty-seven of the 259 respondents (22.0%) would consider strategies different to their present ones, as presented in Table 6.14. A majority recommended option 1 as their ideal strategy. A comparison of the performance between option 2 (present strategy) and option 1 (ideal strategy) is presented in Figure 6.31. Option 1 yielded better quality and satisfaction, whereas option 2 produced better cost and time performance. Overall, option 1 is the better strategy. All differences except time performance were statistically

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Performance comparison between repair strategies of flood damage

Figure 6.30 scenario 16

Table 6.13 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 16 Repair strategy

Option 2

Option 1 Option 2

Option 3

C,q,S,O s

Note: See Table 6.1 for explanation of symbols.

Table 6.14 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 16 Ideal strategy Present strategy

Option 1

Option 1 Option 2 Option 3 Option 4 Option 5 Column total

Option 2

Option 3

1 100.0% 2 4.3%

44 95.7% 4 100.0% 1 100.0% 3 60.0%

2 40.0%

52 91.2%

3 5.3%

Note: See Table 6.2 regarding bold face numbers.

2 3.5%

Row total 1 100.0% 46 100.0% 4 100.0% 1 100.0% 5 100.0% 57 100.0%

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Figure 6.31 Performance comparison between present (option 2) and ideal (option 1) repair strategies of flood damage scenario 16

confirmed. This suggests a preference to employ an ideal strategy which yielded higher quality and satisfaction. However, the ideal strategy was more costly and rather time consuming, which thereby hampered its current utilisation.

6.2.9 Flood damage scenario 17 The scenario was: ‘Following removal of the wall’s plaster, it is found that the wall has been incorrectly constructed’ as presented in Figure 6.32. Three repair strategy options were provided as follows: Option 1: Recommend the wall be demolished and reconstructed. Option 2: Recommend the client be approached and asked to pay for the wall to be correctly constructed. Option 3: Recommend the wall be plastered. Figure 6.33 depicts the range of current practice in dealing with this type of damage. Most respondents (87.1%) recommended option 2, that is to approach and ask the client to pay for the wall to be correctly constructed; some (10.9%) selected option 3 and a few (2.0%) chose option 1. Figure 6.34

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Figure 6.32

Image of flood damage scenario 17

Figure 6.33

Present repair strategies for flood damage scenario 17

103

presents a performance comparison between strategies, including options 2 and 3. Option 3 was better in all performance aspects but quality. Statistical tests confirmed the differences in quality, satisfaction and overall performance. In summary, plastering the wall (i.e. option 3) is the benchmark solution for this scenario.

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Figure 6.34 scenario 17

Performance comparison between repair strategies of flood damage

Of the 254 respondents who responded to this damage scenario, 51 (20.1%) recommended an alternative ideal strategy (i.e. different to that presently used), as presented in Table 6.15. Most respondents recommended option 1 as their ideal strategy. A performance comparison between options 2 (present) and 1 (ideal) is presented in Figure 6.35. Option 1 yielded higher quality and satisfaction, whereas option 2 was cheaper and quicker to implement. All differences except time required were statistically confirmed. Overall, option 1 was the most effective strategy as confirmed by statistical tests. This suggests that option 1 was perceived to be a better strategy in terms of quality and satisfaction; however, it was more expensive and this precludes its utilisation.

Table 6.15 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 17 Ideal strategy Present strategy Option 2 Option 3 Column total

Option 1

Option 2

37 97.4% 4 30.8%

9 69.2%

41 80.4%

9 17.6%

Note: See Table 6.2 regarding bold face numbers.

Option 3

Row total

1 2.6%

38 100.0% 13 100.0%

1 2.0%

51 100.0%

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Figure 6.35 Performance comparison between present (option 2) and ideal (option 1) repair strategies of flood damage scenario 17

6.2.10 Flood damage scenario 18 The scenario was: ‘Floodwater has been in contact with an internal block wall which has a gypsum plaster finish’ as presented in Figure 6.36. Five repair strategies were provided as follows:

Figure 6.36

Image of flood damage scenario 18

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Option 1: Recommend the plaster be cleaned. Option 2: Recommend the plaster be replaced up to the floodwater line (or 15–30 cm above). Option 3: Recommend all the wall’s plaster be replaced. Option 4: Recommend the sections of plaster that have disbonded from the blockwork be replaced. Option 5: Recommend the plaster be replaced with a cement/sand render and a skim finish. The respondents’ present repair strategies are presented in Figure 6.37. A large number (48.8%) recommended option 2, that is replacing the plaster up to the floodwater line (or 15–30 cm above) whereas 26.0% chose option 4. Some selected options 3 (10.2%) and 5 (11.4%) and a few (3.7%) chose option 1. A comparison of the performance of the repair strategies is presented in Figure 6.38. Option 4 was the most cost effective strategy; option 3 provided higher quality and satisfaction, and was considered the quickest. Overall, option 3 was the most effective strategy, but the performance differences compared with the other strategies were marginal (Table 6.16). Nevertheless, the replacement of all the wall’s plaster (i.e. option 3) is the benchmark solution for this scenario. Forty-six of the 263 respondents (17.5%) would consider strategies different from their present ones, as presented in Table 6.17. Option 3 was the most popular ideal strategy, followed by option 2. Comparisons of the performance between present and ideal strategies were conducted in two cases as shown in Figures 6.39 and 6.40. A comparison between options 2 (present strategy) and 3 (ideal strategy) indicated that option 3 provided significantly better quality and satisfaction at significantly greater cost; the time difference was marginal.

Figure 6.37

Present repair strategies for flood damage scenario 18

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Figure 6.38 scenario 18

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Performance comparison between repair strategies of flood damage

Table 6.16 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 18 Repair strategy

Option 3

Option 4

Option 5

C,Q,s

c,S C,Q,S

c,q c C,Q,S

Option 2 Option 3 Option 4

Note: See Table 6.1 for explanation of symbols.

Table 6.17 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 18 Ideal strategy Present strategy Option 1 Option 2 Option 3 Option 4 Option 5 Option 1

3 42.9%

Option 2 Option 4

12 63.2%

Option 5

2 66.7%

Column total

2 4.3%

15 32.6%

Note: See Table 6.2 regarding bold face numbers.

Row total

2 28.6% 13 76.5% 5 26.3% 1 33.3%

1 14.3% 1 5.9%

1 14.3% 3 17.6% 2 10.5%

7 100.0% 17 100.0% 19 100.0% 3 100.0%

21 45.7%

2 4.3%

6 13.0%

46 100.0%

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Figure 6.39 Performance comparison between present (option 2) and ideal (option 3) repair strategies of flood damage scenario 18

Figure 6.40 Performance comparison between present (option 4) and ideal (option 2) repair strategies of flood damage scenario 18

Overall, option 2 (present) was a better strategy, although the difference was only marginal. A comparison between options 4 (present strategy) and 2 (ideal strategy) indicated option 2 to be significantly better in terms of quality and satisfaction but significantly less cost effective; again, the difference in time performance was not significant. Overall, option 2 provided the best performance, although only marginally. This suggests that additional cost precluded the selection of ideal strategies despite these yielding higher quality and satisfaction.

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6.2.11 Flood damage scenario 19 The scenario was: ‘Floodwater has been in contact with an internal block wall which has a cement/sand mix undercoat and a 1 mm plaster skim applied to it’ as presented in Figure 6.41. Five alternative repair strategies were provided as follows:

Figure 6.41

Image of flood damage scenario 19

Option 1: Recommend the plaster be cleaned. Option 2: Recommend the plaster be replaced up to the floodwater line (or 15–30 cm above). Option 3: Recommend all the wall’s plaster be replaced. Option 4: Recommend the sections of plaster that have disbonded from the blockwork be replaced. Option 5: Recommend the plaster be replaced with a cement/sand render and a skim finish. The respondents’ present repair strategies are shown in Figure 6.42. The two most popular strategies are options 2 (42.4%) and 4 (32.7%) and these accounted for more than three-quarters of respondents. Some respondents selected options 1 (8.6%), 3 (8.6%) and 5 (7.8%). A comparison of the performance of the repair strategies is presented in Figure 6.43. As expected, option 1 was the most cost effective strategy, as confirmed by statistical tests

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Figure 6.42

Present repair strategies for flood damage scenario 19

Figure 6.43 scenario 19

Performance comparison between repair strategies of flood damage

(Table 6.18). Options 3 and 5, although the two least cost effective strategies, provided higher quality and satisfaction. Option 1 was considered the quickest strategy to be implemented. Overall, option 1 was the most effective strategy, followed closely by options 3 and 5. Here, there was no significant difference between strategies, except between option 4 (the poorest overall performance) and options 1, 2 and 3 (see Table 6.18). Nonetheless, cleaning the plaster (i.e. option 1) is the benchmark strategy for this scenario. Forty-three of the 267 respondents (16.1%) recommended an alternative ideal strategy (i.e. different to that presently used). Table 6.19 depicts a crosstabulation of respondents who selected an alternative ideal repair strategy; options 2 and 3 were the two most popular. A comparison of the performance

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Table 6.18 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 19 Repair strategy

Option 2

Option 3

Option 4

C,Q,t,S

C,Q,S C,S

C,s,o Q,S,o C,Q,S,o

Option 1 Option 2 Option 3 Option 4

Option 5 C,Q,t,S c,q,s C,Q,S

Note: See Table 6.1 for explanation of symbols.

Table 6.19 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 19 Ideal strategy Present strategy Option 1

Option 2

Option 3

Option 4

Option 5

Row total

7 63.6%

1 9.1%

2 18.2% 2 20.0% 5 22.7%

11 100.0% 10 100.0% 22 100.0%

1 2.3%

9 20.9%

43 100.0%

Option 4

9 40.9%

1 9.1% 8 80.0% 8 36.4%

Column total

16 37.2%

17 39.5%

Option 2

between present and ideal repair strategies was not conducted due to the small sample size in each case (i.e. less than 10 in each cell of the matrix).

6.2.12 Flood damage scenario 20 The scenario was: ‘Floodwater has been in contact with an internal brick wall which is finished with a lime/ox-hair mix and a lime putty finish’ as presented in Figure 6.44. Five repair strategy options were provided as follows: Option 1: Recommend the plaster be cleaned. Option 2: Recommend the plaster be replaced up to the floodwater line (or 15–30 cm above). Option 3: Recommend all the wall’s plaster be replaced. Option 4: Recommend the sections of plaster that have disbonded from the blockwork be replaced. Option 5: Recommend the plaster be replaced with a cement/sand render and a skim finish.

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Figure 6.44

Image of flood damage scenario 20

Figure 6.45 shows present repair strategies as used by the respondents. Opinions were diverse with 39.4% recommending option 2, 26.7% choosing option 3 and 19.9% option 4. Some respondents (10%) selected option 5 and a few (4.0%) chose option 1. Figure 6.46 compares the performance of the various repair strategies. Option 1 was the most cost effective strategy, whereas option 3 was the most costly. Option 3 yielded better quality, followed closely by option 5. Option 1 yielded the poorest quality outcome. A similar tendency was discovered for satisfaction criteria. This demonstrates a trade off between cost and quality/satisfaction. Overall, option 3 was the

Figure 6.45

Present repair strategies for flood damage scenario 20

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Figure 6.46 scenario 20

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Performance comparison between repair strategies of flood damage

most effective strategy. It is interesting to note that there was no significant difference between options 3 and 5 (Table 6.20) suggesting that these two strategies deliver a similar performance. Nevertheless, the replacement of all the wall’s plaster (i.e. option 3) is the benchmark solution for this scenario. Forty-two of the 262 respondents (16.0%) would consider strategies different from their present ones, as presented in Table 6.21. Option 3 was the most favoured strategy. A comparison of performance between options 2 (present strategy) and 3 (ideal strategy) is presented in Figure 6.47. Option 3 yielded better quality and satisfaction, whereas option 2 required less cost and time to be implemented. Overall, option 3 was a better strategy. Statistical tests confirmed the performance differences in cost, quality and satisfaction. This suggests that the increased cost incurred is the primary reason for not choosing the ideal strategy.

Table 6.20 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 20 Repair strategy Option 1 Option 2 Option 3 Option 4

Option 2

Option 3

Option 4

C,Q

C,Q,S C,Q,S,o

c c C,Q,S

Note: See Table 6.1 for explanation of symbols.

Option 5 C,Q,t,S c,S C,Q,t,S

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Table 6.21 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 20 Ideal strategy Present strategy Option 1 Option 2 Option 3 Option 4 Option 5 Option 1 Option 2

2 33.3%

1 16.7 18 81.8%

4 36.4%

3 27.3% 1 50.0%

6 14.3%

23 54.8%

1 4.5%

1 16.7

2 33.3% 3 13.6% 1 100.0% 4 36.4%

6 100.0% 22 100.0% 1 100.0% 11 100.0% 2 100.0%

1 2.4%

10 23.8%

42 100.0%

Option 3 Option 4 Option 5

1 50.0%

Column total

2 4.8%

Row total

Note: See Table 6.2 regarding bold face numbers.

Figure 6.47 Performance comparison between present (option 2) and ideal (option 3) repair strategies of flood damage scenario 20

6.2.13 Flood damage scenario 21 The scenario was: ‘Floodwater has been in contact with an internal timber partition wall’ as presented in Figure 6.48. Four repair strategies were provided as follows: Option 1: Recommend all the plasterboard be replaced. Option 2: Recommend plasterboard that has been in contact with floodwater be replaced.

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Option 3: Recommend the timber components and the plasterboard be replaced. Option 4: Recommend the timber and plasterboard that have been in contact with the floodwater be replaced.

Figure 6.48

Image of flood damage scenario 21

A reasonable number of respondents recommended a different strategy from those provided and therefore, one more option was established as follows: Option 5: Attempt to dry and sanitise the wall and then reassess after it is dry. The respondents’ present repair strategies are shown in Figure 6.49. Many of the respondents (44.7%) recommended option 2, i.e. replacing plasterboard

Figure 6.49

Present repair strategies for flood damage scenario 21

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Figure 6.50 scenario 21

Performance comparison between repair strategies of flood damage

that has been in contact with floodwater, 19.7% selected option 1, some chose options 3 (14.4%) and 4 (16.7%) and a few (4.5%) recommended option 5. A comparison of performance between strategies is presented in Figure 6.50. Option 5 was considered the most cost effective strategy and this was confirmed by statistical tests (Table 6.22); option 3 was the most costly. Option 3 provided higher quality as confirmed by statistical tests. The differences in time performance were not significant, although option 2 was considered the quickest to implement. Option 1 delivered higher satisfaction and overall was the optimum strategy; hence it provides the benchmark solution for this scenario. Fifty-one of the 268 respondents (19.0%) would recommend strategies different from their present ones, as presented in Table 6.23. Option 3 was the most favoured ideal repair strategy, followed closely by option 4. A comparison of performance between present and ideal strategies is presented in Figures 6.51 and 6.52. A comparison between options 2 (present strategy) and 3 (ideal strategy) indicated that option 3 was better in all aspects of Table 6.22 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 21 Repair strategy Option 1 Option 2 Option 3 Option 4

Option 2

Option 3

Option 4

Option 5

C,q,S,o

q C,Q,S

s,o C,S c,Q

C,q,S C C,Q,s C,s

Note: See Table 6.1 for explanation of symbols.

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Table 6.23 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 21 Ideal strategy Present strategy

Option 1

Option 2

Option 1 Option 2

8 21.1%

Option 3

Option 4

Row total

5 83.3% 15 39.5%

1 16.7% 15 39.5% 1 50.0%

6 100.0% 38 100.0% 2 100.0% 2 100.0% 3 100.0%

17 33.3%

51 100.0%

1 50.0%

Option 4

2 100.0%

Option 5 Column total

Option 3

3 100.0% 8 15.7%

4 7.8%

22 43.1%

Note: See Table 6.2 regarding bold face numbers.

performance except cost. Statistical tests confirmed the performance differences in cost, quality and satisfaction. A comparison between options 2 (present strategy) and 4 (ideal strategy) indicated that option 4 produced significantly better quality and satisfaction. However, option 4 was significantly inferior in cost performance, whilst option 2 was considered to be slightly quicker. Overall, option 4 was significantly better. These comparisons indicate that high cost was the primary reason for not choosing alternative ideal strategies.

Figure 6.51 Performance comparison between present (option 2) and ideal (option 3) repair strategies of flood damage scenario 21

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Figure 6.52 Performance comparison between present (option 2) and ideal (option 4) repair strategies of flood damage scenario 21

6.2.14 Flood damage scenario 22 The scenario was: ‘Floodwater has been in contact with an internal metal-framed partition wall’ as presented in Figure 6.53. Four repair strategy options were provided as follows:

Figure 6.53

Image of flood damage scenario 22

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Option 1: Recommend all the plasterboard be replaced. Option 2: Recommend plasterboard that has been in contact with floodwater be replaced. Option 3: Recommend the metal components and the plasterboard be replaced. Option 4: Recommend the metal and plasterboard that have been in contact with the floodwater be replaced. A reasonable number of respondents recommended a different strategy from those provided and therefore, one more option was established as follows: Option 5: Attempt to dry and sanitise the wall and then reassess and check for corrosion after it is dry. Figure 6.54 depicts present repair strategies as recommended by the respondents, almost half of whom (49.8%) recommended option 2, i.e. replacing plasterboard that has been in contact with floodwater, whereas 22.6% selected option 1. Some recommended options 3 (9.2%) and 4 (13.4%), and a few (5.0%) chose option 5. A performance comparison between strategies is presented in Figure 6.55. Option 5 was the most cost effective strategy, whereas option 3 was the most costly, both being statistically confirmed (Table 6.24). A similar tendency was found in quality and satisfaction comparisons where option 3 yielded the highest quality and satisfaction. Option 3 was also the quickest to implement. Overall, option 3 was the optimum strategy, followed closely by option 1. The differences in overall performance were found to be marginal (i.e. differences were not statistically significant; Table 6.24). Nevertheless, the replacement of metal components and plasterboard (i.e. option 3) is the benchmark solution for this scenario.

Figure 6.54

Present repair strategies for flood damage scenario 22

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Figure 6.55 scenario 22

Performance comparison between repair strategies of flood damage

Table 6.24 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 22 Repair strategy

Option 2

Option 3

C,Q,s

C C,Q,S

Option 1 Option 2 Option 3 Option 4

Option 4

Option 5

C,t C,q,t,s

C,Q,S C,s C,Q,S C

Note: See Table 6.1 for explanation of symbols.

Table 6.25 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 22 Ideal strategy Present strategy

Option 1

Option 2

Option 1 Option 2 Option 4

8 33.3% 1 16.7%

Option 5 Column total

Option 3

Option 4

4 100.0% 7 29.2% 5 83.3%

9 37.5%

16 44.4%

9 25.0%

2 100.0% 9 25.0%

2 5.6%

Row total 4 100.0% 24 100.0% 6 100.0% 2 100.0% 36 100.0%

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Of the 265 respondents who responded to this scenario, 36 (13.6%) recommended an alternative ideal strategy, as presented in Table 6.25. Option 3 was the most popular strategy, suggesting an emphasis on higher quality and satisfaction. A comparison between present and ideal repair strategies was not conducted due to the small sample size.

6.3

Summary This section provides a summary of the results for each scenario previously presented. Tables 6.26–6.39 present a summary of the response to each scenario. Current strategies are listed in descending order of popularity, and ranked in terms of their performance (cost, quality, time, satisfaction and overall). For each scenario, a benchmark is provided based on the overall performance. Implications arising from these results are also discussed.

6.3.1 Scenario 9: ‘The external wall of the property is brickwork with cement mortar joints’ A summary of the analysis for scenario 9 is provided in Table 6.26. Most respondents recommended either cleaning the wall (48.7%) or cleaning and repainting the wall (36.2%). The cleaning strategy was the most cost effective and delivered marginally better quality, which is rather surprising given the limited work involved. As expected, leaving the wall alone is the quickest strategy; however, it delivered poorer quality and satisfaction. Sandblasting the wall to remove any flood debris yielded higher satisfaction, although it was also the most costly and time consuming strategy to be implemented. This suggests the presence of mutual exclusivity between cost–time and quality–satisfaction, i.e. the strategy which delivered higher quality and/or satisfaction is likely to involve higher cost and/or longer time, and vice versa. In summary, cleaning the wall is the benchmark strategy for this scenario. Table 6.26 Summary of the analysis for scenario 9: ‘The external wall of the property is brickwork with cement mortar joints’ Performance ranking Repair strategy Clean the wall Clean and repaint the wall Sandblast the wall to remove any flood debris Leave the wall alone Note: C, cost; Q, quality; T, time; S, satisfaction; O, overall.

Chosen by (%)

C

Q

T

S

O

48.7 36.2 7.9 7.2

1 3 4 2

1 2 3 4

2 3 4 1

3 2 1 4

1 3 4 2

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6.3.2 Scenario 10: ‘The external wall of the property has a rendered finish’ A summary of the analysis for scenario 10 is provided in Table 6.27; there was no consensus regarding present repair strategies for this scenario. Of the respondents, 32.8% recommended that areas of the render that had become unbonded from the wall substrate be replaced. The performance of this strategy was somewhat poor and, in fact, its overall performance was poorer than other strategies. Cleaning was recommended by 25.4%, was the most cost effective and quickest strategy, and delivered better overall performance; however, quality and satisfaction were rather poor. Cleaning the render first and then replacing areas of render that had spalled and become unbonded from the wall substrate yielded higher quality, although this strategy was more time consuming than others. Removal and replacement of all the render yielded higher satisfaction but was perceived as the most costly strategy. These results indicate that there is no strategy which yields the most effective performance in all aspects. The analysis also indicated that several strategies requiring the replacement of areas of the render that had spalled and/or unbonded delivered a similar performance outcome. Therefore, these strategies could be considered to be so similar that damage assessors could choose any one of them without worrying about performance differences. In summary, cleaning the render is the benchmark strategy for this scenario.

Table 6.27 Summary of the analysis for scenario 10: ‘The external wall of the property has a rendered finish’ Performance ranking Repair strategy Replace areas of the render that have become unbonded from the wall substrate Clean the render Replace areas of the render that have spalled Clean the render and then replace areas of the render that have become unbonded from the wall substrate Replace areas of the render that have spalled and become unbonded from the wall substrate Clean the render first, and then replace areas of the render that have spalled and become unbonded from the wall substrate Remove and replace all of the render Leave the wall alone Sandblast the wall to remove any flood debris Note: See Table 6.26 for explanation of symbols.

Chosen by (%)

C

Q

T

S

O

32.8 25.4 10.2

5 1 2

6 5 4

6 1 4

5 6 7

7 1 6

8.6

6

3

2

3

3

7.8

2

7

3

4

5

7.8 3.9 2.3 1.2

2 7 – –

1 2 – –

7 5 – –

2 1 – –

4 2 – –

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6.3.3 Scenario 11: ‘The external wall of the property has a pebbledash finish’ Table 6.28 presents a summary of the analysis for scenario 11. There was no dominant repair strategy for this scenario. Replacing areas of the pebbledash render that have become unbonded from the wall substrate was the most popular strategy as recommended by 30.4% of respondents. This was closely followed by cleaning the pebbledash render (chosen by 27.3%), which was the most cost effective, least time consuming and most effective strategy overall, although it delivered somewhat poorer quality and satisfaction. The analysis suggested that several strategies requiring replacement of areas of the pebbledash render that had spalled and/or unbonded gave a similar performance outcome. Therefore, it could be concluded that these strategies are similar in nature and damage assessors could choose any of them without worrying about performance differences. In summary, cleaning is the benchmark solution for this scenario.

Table 6.28 Summary of the analysis for scenario 11: ‘The external wall of the property has a pebbledash finish’ Performance ranking Repair strategy Replace areas of the pebbledash render that have become unbonded from the wall substrate Clean the pebbledash render Replace areas of the pebbledash render that have spalled Clean the pebbledash render first, and then replace areas of the render that have spalled and become unbonded from the wall substrate Replace areas of the pebbledash render that have spalled and become unbonded from the wall substrate Clean the pebbledash render, and then replace areas of the render that have become unbonded from the wall substrate Leave the wall alone Remove and replace all of the pebbledash render Sandblast the wall to remove any flood debris Note: See Table 6.26 for explanation of symbols.

Chosen by (%)

C

Q

T

S

O

30.4 27.3

5 1

3 5

5 1

5 6

5 1

10.7

6

4

2

4

6

8.7

2

1

6

3

2

7.9

3

6

4

1

4

7.5 3.2 3.2 1.2

3 – – –

2 – – –

3 – – –

2 – – –

3 – – –

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6.3.4 Scenario 12: ‘An internal wall of the flood damaged property is constructed of brickwork with a paint finish applied directly to it’ Table 6.29 presents a summary of the analysis for scenario 12. Cleaning and repainting the wall was the dominant strategy as recommended by 86% of the respondents. This is the benchmark strategy for this scenario. Further analysis suggested that sandblasting the wall to remove any germs was almost as effective as cleaning and repainting. Table 6.29 Summary of the analysis for scenario 12: ‘An internal wall of the flood damaged property is constructed of brickwork with a paint finish applied directly to it’ Performance ranking Repair strategy Clean and repaint the wall Sandblast the wall to remove any germs Repaint the wall Clean, plaster and decorate the wall Repoint the wall

Chosen by (%)

C

Q

T

S

O

86.0 5.2 4.0 3.6 1.2

1 2 – – –

1 2 – – –

1 2 – – –

1 2 – – –

1 2 – – –

Note: See Table 6.26 for explanation of symbols.

6.3.5 Scenario 13: ‘An internal wall of the flood damaged property has been covered with ceramic tiles’ A summary of the analysis for scenario 13 is presented in Table 6.30. Almost all respondents recommended either replacing all tiles (53.9%) or replacing only ‘loose’ tiles (41.8%). Replacing all tiles yielded higher quality, satisfaction and overall performance. It is rather surprising that replacing only ‘loose’ tiles was the most cost effective strategy, whereas leaving the wall alone was more expensive, perhaps because of long term damage caused by failing to check and/or replace ‘damaged’ tiles. As expected, leaving the wall alone is the Table 6.30 Summary of the analysis for scenario 13: ‘An internal wall of the flood damaged property has been covered with ceramic tiles’ Performance ranking Repair strategy Replace all tiles Replace only ‘loose’ tiles Leave the wall alone Note: See Table 6.26 for explanation of symbols.

Chosen by (%)

C

Q

T

S

O

53.9 41.8 4.3

3 1 2

1 2 3

3 2 1

1 3 2

1 3 2

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quickest strategy. Further analysis suggested that replacing only ‘loose’ tiles delivers similar performance to leaving the wall alone, which therefore undervalues replacing only ‘loose’ tiles as a repair strategy. The analysis also indicated that the time required to replace all tiles is the same as that required to replace just the ‘loose’ tiles, perhaps because of the time required to check and recheck any loose tiles and the associated rework costs. Therefore, damage assessors should consider this in the allocation of workmanship costs. Replacing all tiles was found to be the most popular ideal strategy, which delivered significantly better quality, satisfaction and overall performance than the present strategy. In summary, the replacement of all tiles is the benchmark strategy for this scenario.

6.3.6 Scenario 14: ‘An internal wall of the flood damaged property has been covered with a wood veneer on timber grounds’ A summary of the analysis for scenario 14 is presented in Table 6.31. A majority of the respondents (70.8%) recommended the wood veneer be replaced, which gave better performance in all aspects except cost; 25.5% advocated replacing the wood veneer in contact with floodwater, whilst a few (3.7%) recommended the veneer be cleaned, which was the most cost effective strategy. Further analysis revealed that the time required to implement these options was approximately the same, which could be taken into consideration when selecting an appropriate strategy. In summary, the replacement of the wood veneer is the benchmark solution for this scenario. Table 6.31 Summary of the analysis for scenario 14: ‘An internal wall of the flood damaged property has been covered with a wood veneer on timber grounds’ Performance ranking Repair strategy Replace the wood veneer Replace the wood veneer in contact with floodwater Clean the wood veneer

Chosen by (%)

C

Q

T

S

O

70.8 25.5

3 2

1 2

1 3

1 3

1 3

3.7

1

3

2

2

2

Note: See Table 6.26 for explanation of symbols.

6.3.7 Scenario 15: ‘An internal wall of the flood damaged property has been decorated with wallpaper’ Table 6.32 provides a summary of the analysis for scenario 15. Almost all respondents (95.9%) recommended replacing all wallpaper, which performed better in all aspects except cost. Replacing only flood damaged wallpaper was the most cost effective strategy. The analysis revealed that time taken to

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Table 6.32 Summary of the analysis for scenario 15: ‘An internal wall of the flood damaged property has been decorated with wallpaper’ Performance ranking Repair strategy

Chosen by (%)

C

Q

T

S

O

95.9 4.1

2 1

1 2

1 2

1 2

1 2

Replace all wallpaper Replace only flood damaged wallpaper Note: See Table 6.26 for explanation of symbols.

implement these strategies was similar, and therefore selection should be based on cost, quality and satisfaction. In sum, the replacement of all wallpaper is the benchmark strategy for this scenario.

6.3.8 Scenario 16: ‘An external wall of a flood damaged property has evidence of a rising damp problem’ A summary of the analysis for scenario 16 is provided in Table 6.33. The majority of the respondents (76.4%) recommended approaching the client to pay for curing the rising damp problem and then replacing the plaster; this strategy was considered the most cost effective. Some respondents (15.8%) recommended injecting the wall with a dpc and then replacing the plaster, which delivered better performance in all aspects except cost. Further analysis uncovered that injecting the wall with a dpc and replacing the plaster yielded a similar performance outcome to replacing the plaster with cement/sand render and skimming with gypsum. Moreover, there were no time differences in the implementation of all strategies; therefore selection of a repair strategy should consider cost, quality and satisfaction. Injecting the wall with a dpc and then replacing the plaster was the most popular ideal strategy. A comparison between present and ideal strategies indicated that the ideal strategy, Table 6.33 Summary of the analysis for scenario 16: ‘An external wall of a flood damaged property has evidence of a rising damp problem’ Performance ranking Repair strategy Approach the client to pay for curing the rising damp problem and replace the plaster Inject the wall with a dpc and replace the plaster Replace the plaster with cement/sand render and skim with gypsum Repaint the wall after it has dried Patch the wall up Note: See Table 6.26 for explanation of symbols.

Chosen by (%)

C

Q

T

S

O

76.4 15.8

1 3

3 1

2 1

3 1

3 1

4.1 3.3 0.4

2 – –

2 – –

2 – –

2 – –

2 – –

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which delivered higher quality and satisfaction, was prohibitively expensive. Injecting the wall with a dpc and replacing the plaster is the benchmark strategy for this scenario.

6.3.9 Scenario 17: ‘Following removal of the wall’s plaster, it is found that the wall has been incorrectly constructed’ Table 6.34 summarises the analysis for scenario 17. Almost all respondents (87.1%) recommended the client be approached and asked to pay for the wall to be correctly constructed; 10.9% recommended the wall be plastered, which was better in all aspects of performance except quality. Interestingly, approaching and asking the client to pay for the wall to be constructed yielded a better quality repair, but not greater satisfaction. This scenario demands more extensive work at the cost of the client. Further analysis revealed that there were no cost and time differences between these two strategies and therefore, quality and satisfaction were two criteria to be considered when selecting an appropriate repair strategy. Thus, if damage assessors prefer better quality, they should approach and ask the client to pay for the wall to be correctly constructed; if they favour higher satisfaction, they should recommend the wall be plastered. Nevertheless, plastering the wall is the benchmark solution for this scenario. Demolishing and constructing the wall was the most popular ideal strategy. A comparison between present and ideal strategies revealed that demolishing and constructing the wall delivered better quality and satisfaction; however, this was prohibitively expensive. Table 6.34 Summary of the analysis for scenario 17: ‘Following removal of the wall’s plaster, it is found that the wall has been incorrectly constructed’ Performance ranking Repair strategy Approach and ask the client to pay for the wall to be correctly constructed Plaster the wall Demolish and reconstruct the wall

Chosen by (%)

C

Q

T

S

O

87.1 10.9 2.0

2 1 –

1 2 –

2 1 –

2 1 –

2 1 –

Note: See Table 6.26 for explanation of symbols.

6.3.10 Scenario 18: ‘Floodwater has been in contact with an internal block wall which has a gypsum plaster finish’ Table 6.35 summarises the analysis for scenario 18. Almost half (48.8%) of the respondents recommended the plaster be replaced up to the floodwater line

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Table 6.35 Summary of the analysis for scenario 18: ‘Floodwater has been in contact with an internal block wall which has a gypsum plaster finish’ Performance ranking Repair strategy Replace the plaster up to the floodwater line (or 15–30 cm above) Replace the sections of plaster that have disbonded from the blockwork Replace the plaster with a cement/sand render and a skim finish Replace all the wall’s plaster Clean the plaster

Chosen by (%)

C

Q

T

S

O

48.8

2

3

3

3

3

26.0

1

4

2

4

4

11.4 10.2 3.7

3 4 –

2 1 –

4 1 –

2 1 –

2 1 –

Note: See Table 6.26 for explanation of symbols.

or 15–30 cm above, for which performance was considered moderate, whereas 26.0% recommended the sections of plaster that had disbonded from the blockwork be replaced, which was the most cost effective strategy. Replacing all the wall’s plaster performed better in all aspects except cost. Further analysis suggested that time and overall performance were similar for all strategies. Therefore, damage assessors should consider an appropriate strategy based on cost, quality and satisfaction. Thus, if higher quality and satisfaction are favoured, all the wall’s plaster should be replaced, whereas if a cheaper option is preferred, only sections of the plaster that have disbonded from the blockwork should be replaced. Nonetheless, the analysis showed that the replacement of all the wall’s plaster is the benchmark strategy for this scenario. Replacing all the wall’s plaster and replacing the plaster up to the floodwater line were the two most popular ideal strategies as selected by 45.7% and 32.6% of those who considered an alternative repair strategy. Deeper analysis indicated that high cost precluded the selection of ‘ideal’ strategies despite these delivering higher quality and satisfaction.

6.3.11 Scenario 19: ‘Floodwater has been in contact with an internal block wall which has a cement/sand mix undercoat and a 1 mm plaster skim applied to it’ A summary of the analysis for scenario 19 is presented in Table 6.36. A majority of the respondents recommended either the plaster be replaced up to the floodwater line (42.4%) or the sections of plaster that have disbonded from the blockwork be replaced (32.7%). Although these two strategies were recommended by most, their performance was moderate. As expected, cleaning the plaster was the most cost effective and quickest strategy to be implemented. Replacing the plaster with a cement/sand render and

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Table 6.36 Summary of the analysis for scenario 19: ‘Floodwater has been in contact with an internal block wall which has a cement/sand mix undercoat and a 1 mm plaster skim applied to it’ Performance ranking Repair strategy Replace the plaster up to the floodwater line (or 15–30 cm above) Replace the sections of plaster that have disbonded from the blockwork Clean the plaster Replace all the wall’s plaster Replace the plaster with a cement/sand render and a skim finish

Chosen by (%)

C

Q

T

S

O

42.4

3

3

3

3

4

32.7 8.6 8.6

2 1 5

4 5 2

2 1 4

4 5 1

5 1 2

7.8

4

1

5

2

3

Note: See Table 6.26 for explanation of symbols.

a skim finish provided a better quality repair, whilst replacing all the wall’s plaster delivered higher satisfaction. Overall, cleaning was the most effective strategy, although not markedly so. Nonetheless, it is the benchmark solution for this scenario.

6.3.12 Scenario 20: ‘Floodwater has been in contact with an internal brick wall which is finished with a lime/ox-hair mix and a lime putty finish’ A summary of the analysis for scenario 20 is provided in Table 6.37. The opinions of the respondents were diverse regarding this scenario, with 39.4% recommending the plaster be replaced up to the floodwater line which provided moderate performance; 26.7% recommended all the wall’s plaster be Table 6.37 Summary of the analysis for scenario 20: ‘Floodwater has been in contact with an internal brick wall which is finished with a lime/ox-hair mix and a lime putty finish’ Performance ranking Repair strategy Replace the plaster up to the floodwater line (or 15–30 cm above) Replace all the wall’s plaster Replace the sections of plaster that have disbonded from the blockwork Replace the plaster with a cement/sand render and a skim finish Clean the plaster Note: See Table 6.26 for explanation of symbols.

Chosen by (%)

C

Q

T

S

O

39.4 26.7

3 5

3 1

4 3

3 1

4 1

19.9

2

4

2

4

4

10.0 4.0

4 1

2 5

5 1

2 5

2 3

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replaced, which provided higher quality and satisfaction. Quite a considerable number (19.9%) advocated replacing the sections of plaster that had disbonded from the blockwork. Cleaning the plaster was the most cost effective and quickest strategy. It is worth noting the presence of performance mutual exclusivity between replacing all the wall’s plaster and cleaning the plaster; That is, the former yielded higher quality and satisfaction but was expensive, whilst the latter was cheapest but yielded poorer quality and satisfaction. Further analysis also revealed that replacing all the wall’s plaster and replacing the plaster with a cement/sand render and a skim finish delivered the same level of performance. The analysis indicates that the replacement of all the wall’s plaster is the benchmark solution for this scenario.

6.3.13 Scenario 21: ‘Floodwater has been in contact with an internal timber partition wall’ Table 6.38 presents a summary of the analysis for scenario 21. The opinions of the respondents were quite diverse, with 44.7% recommending that plasterboard that has been in contact with floodwater be replaced, which was the quickest strategy, and 19.7% recommending that all plasterboard be replaced, which yielded higher satisfaction. Replacing timber components and plasterboard yielded a better quality repair. As expected, attempting to dry and sanitise the wall and then reassess after drying was the most cost effective strategy. Overall, replacing all plasterboard was the optimum strategy. Further analysis revealed that all strategies required a similar time, suggesting that consideration for selecting repair strategy should be based on cost, quality and satisfaction. Nevertheless, the replacement of all plasterboard is the benchmark solution for this scenario. The two most popular ideal strategies as selected by 43.1% and 33.3% of those who considered an alternative Table 6.38 Summary of the analysis for scenario 21: ‘Floodwater has been in contact with an internal timber partition wall’ Performance ranking Repair strategy Replace plasterboard that has been in contact with floodwater Replace all plasterboard Replace timber and plasterboard that have been in contact with the floodwater Replace timber components and plasterboard Attempt to dry and sanitise and then reassess after drying Note: See Table 6.26 for explanation of symbols.

Chosen by (%)

C

Q

T

S

O

44.7 19.7

2 4

4 2

1 2

4 1

4 1

16.7 14.4

3 5

3 1

4 3

3 2

5 2

4.5

1

5

5

5

3

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repair strategy were replacing timber components and plasterboard and replacing timber and plasterboard that have been in contact with the floodwater, respectively. Performance comparisons between present and ideal strategies suggested that high cost precluded the selection of ideal strategies which delivered higher quality and satisfaction.

6.3.14 Scenario 22: ‘Floodwater has been in contact with an internal metal-framed partition wall’ Table 6.39 presents a summary of the analysis for scenario 22. The opinions of the respondents were somewhat diverse, with 49.8% recommending that plasterboard that has been in contact with floodwater be replaced. However, despite this being the most popular strategy, it yielded only moderate performance. More than one fifth (22.6%) recommended all plasterboard be replaced, again with only moderate performance. Replacing metal components and plasterboard performed better in all aspects except cost. As expected, attempting to dry and sanitise the wall and then reassessing and checking for corrosion after drying was the most cost effective solution. Although replacing metal components and plasterboard performed better overall, the superiority of this option was only marginal. Nevertheless, it provides the benchmark solution for this scenario. The next chapter will deal with the reinstatement of flood damaged doors and windows.

Table 6.39 Summary of the analysis for scenario 22: ‘Floodwater has been in contact with an internal metal-framed partition wall’ Performance ranking Repair strategy Replace plasterboard that has been in contact with floodwater Replace all plasterboard Replace metal and plasterboard that have been in contact with the floodwater Replace metal components and plasterboard Attempt to dry and sanitise and then reassess and check corrosion after drying Note: See Table 6.26 for explanation of symbols.

Chosen by (%)

C

Q

T

S

O

49.8 22.6

2 4

4 2

2 3

4 2

3 2

13.4 9.2

3 5

3 1

4 1

3 1

4 1

5.0

1

5

5

5

4

7

7.1

Reinstatement of Flood Damaged Doors and Windows Introduction This chapter presents the assessment of several flood damaged doors and windows commonly found in domestic properties. Five scenarios are presented, followed by a discussion of the remedial solutions indicated by the respondents including their perceived performance. First, the results and analysis are presented, followed by a detailed discussion of the findings. Finally, a summary and a discussion of the implications of the findings are presented.

7.2

Results and discussion For each scenario, the digital image and the repair strategy options are first presented. Then the respondents’ present strategies are presented and discussed, followed by comparative analysis between the strategies. After this, preferences for ideal strategies are presented and discussed. A comparison of the performance of these ideal strategies with that of current practice is then given.

7.2.1 Flood damage scenario 23 The scenario was: ‘A flood damaged property has a softwood front door that has been in contact with floodwater’ as presented in Figure 7.1. Four repair strategy options were provided as follows: Option 1: Option 2: Option 3: Option 4:

Recommend the door be replaced. Recommend the door be repainted. Allow the door to dry out and then assess the damage. Clean the door only.

Figure 7.2 shows present repair strategies of the respondents, most (81.4%) of whom recommended option 3, some (16.2%) option 1 and a few options 2

132

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Figure 7.1

133

Image of flood damage scenario 23

(1.2%) and 4 (1.2%). A performance comparison between strategies is presented in Figure 7.3. Option 1 yielded higher quality and satisfaction; however, it was considered more costly than option 3, as confirmed by statistical tests. Option 1 was also better in time and overall performance, but the differences were not significant. This suggests that replacing the door provides better quality and higher satisfaction, but is more expensive than allowing the door to dry out and then assessing the damage. Replacement of the door (i.e. option 1) is the benchmark solution for this scenario. Fifty-seven of the 267 respondents (21.3%) recommended an alternative ideal strategy (i.e. different to that presently used), as presented in Table 7.1. Option 1 was the most favoured ideal repair strategy, being chosen by almost all of these respondents (96.5%). Figure 7.4 compares the performance of

Figure 7.2

Present repair strategies for flood damage scenario 23

Figure 7.3 Performance comparison between repair strategies of flood damage scenario 23 Table 7.1 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 23 Ideal strategy Present strategy

Option 1

Option 1 Option 2 Option 3 Column total

Option 3

Row total

2 100.0%

2 100.0% 1 100.0% 54 100.0%

2 3.5%

57 100.0%

1 100.0% 54 100.0% 55 96.5%

Note: Bold face indicates that the ‘quantity’ is sufficient for further statistical comparison (defined as at least 10).

Figure 7.4 Performance comparison between present (option 3) and ideal (option 1) repair strategies of flood damage scenario 23

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options 3 (present strategy) and 1 (ideal strategy). Option 1 was the most effective strategy in all aspects except cost performance, this being confirmed by statistical tests; thus the increased cost involved prevented many experts from employing option 1, even though it yielded higher quality and satisfaction.

7.2.2 Flood damage scenario 24 The scenario was: ‘A flood damaged property has double glazed hardwood patio doors that have been in contact with floodwater’ as presented in Figure 7.5. Five repair strategies were provided as follows: Option 1: Option 2: Option 3: Option 4: Option 5:

Recommend the door be replaced. Recommend the door be repainted. Allow the door to dry out and then assess the damage. Clean the door only. Recommend replacement of the glazing units if the seals have perished.

A reasonable number of respondents chose multiple strategies and therefore, one more option was established, representing a combination of the above options. This was defined as follows: Option 6: Allow the door to dry out and then assess the damage, before replacing the glazing units if the seals have perished (options 3 and 5).

Figure 7.5

Image of flood damage scenario 24

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The respondents’ present repair strategies are presented in Figure 7.6. Most respondents (75.7%) chose option 3, i.e. they would allow the door to dry out and then assess the damage, whereas 16.3% selected option 6, i.e. they would allow the door to dry out and then assess the damage before recommending replacement of the glazing units if the seals had perished. Option 6 highlights the need to make a thorough assessment before any repair decisions are taken: it is worth noting the high number of respondents who recommended this, suggesting that this option is an important repair strategy. Few respondents selected options 1 (2.4%), 4 (3.2%) and 5 (1.6%), and very few (0.8%) chose option 2. A comparison of the performance of the different strategies is presented in Figure 7.7. Option 6 was most effective in all

Figure 7.6

Present repair strategies for flood damage scenario 24

Figure 7.7 Performance comparison between repair strategies of flood damage scenario 24

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aspects except cost performance. However, statistical tests confirmed the performance differences only in cost and satisfaction, indicating that option 6 produces higher satisfaction but is more expensive than option 3. The overall performance scores reveal that allowing the door to dry out and then assessing the damage before replacing the glazing units if the seals have perished, is the benchmark strategy for this scenario. Of the 267 respondents who responded to this scenario, 52 (19.5%) would consider an alternative ideal repair strategy (i.e. different to that presently used), as presented in Table 7.2. Option 1 was the most favoured strategy, as chosen by most of these respondents (78.8%). Comparisons of the performance between present and ideal strategies are shown in Figures 7.8 and 7.9. A comparison between options 3 (present strategy) and 1 (ideal strategy) revealed that option 1 was better in all aspects except cost performance, as confirmed statistically. A similar tendency also applied in the comparison between options 6 (present strategy) and 1 (ideal strategy); however, only differences in cost performance and satisfaction were statistically confirmed. Generally, option 1 delivered better quality, time, satisfaction and overall performance, but at greater expense. These respondents would have preferred to adopt option 1; however, the higher costs incurred precluded its use.

Table 7.2 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 24 Ideal strategy Present strategy

Option 1 Option 2 Option 3 Option 5 Option 6

Row total

2 100.0%

2 100.0% 1 100.0% 36 100.0% 1 100.0% 2 100.0% 10 100.0%

Option 1 Option 2 Option 3 Option 4 Option 5 Option 6 Column total

28 77.8% 1 100.0% 2 100.0% 10 100.0%

1 2.8%

41 78.8%

1 1.9%

Note: See Table 7.1 regarding bold face numbers.

2 3.8%

1 100.0% 5 13.9%

2 5.6%

6 11.5%

2 3.8%

52 100.0%

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Figure 7.8 Performance comparison between present (option 3) and ideal (option 1) repair strategies of flood damage scenario 24

Figure 7.9 Performance comparison between present (option 6) and ideal (option 1) repair strategies of flood damage scenario 24

7.2.3 Flood damage scenario 25 The scenario was: ‘A flood damaged property has hollow cellular type infill wooden doors that have been in contact with floodwater’ as presented in Figure 7.10. Four repair strategy options were provided as follows: Option 1: Recommend the door be replaced. Option 2: Recommend the door be repainted/revarnished.

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Option 3: Allow the door to dry out and then assess the damage. Option 4: Clean the door only.

Figure 7.10

Image of flood damage scenario 25

Figure 7.11 shows the respondents’ present repair strategies: most (78.8%) chose option 1, i.e. replacing the door, some (20.8%) recommended option 3, but only one respondent (0.4%) chose option 4. None selected option 3, suggesting that repainting/revarnishing the door is not a feasible strategy in these circumstances. A comparison of the performance between options 1 and 3 is presented in Figure 7.12. Option 1 was better in all aspects except cost, as confirmed statistically. Although option 1 was perceived to be more costly than option 3, it was preferred by most respondents, suggesting that

Figure 7.11

Present repair strategies for flood damage scenario 25

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Figure 7.12 scenario 25

Performance comparison between repair strategies of flood damage

cost is not the most important consideration in selecting solutions for this scenario. Replacement of the door is the benchmark solution for this scenario. Only 17 of the 268 respondents (6.3%) recommended an alternative ideal strategy (i.e. different to that presently used), as presented in Table 7.3. Option 1 was the most popular strategy. All respondents who chose option 3 would recommend option 1 instead. A comparison of the performance between options 3 (present strategy) and 1 (ideal strategy) is presented in Figure 7.13. The results, which were also statistically confirmed, were consistent with the previous comparison in that option 1 was better in all aspects except cost performance.

Table 7.3 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 25 Ideal strategy Present strategy

Option 1

Option 4

Row total

1 100.0%

1 100.0% 16 100.0%

1 5.9%

17 100.0%

Option 1 Option 3

16 100.0%

Column total

16 94.1%

Note: See Table 7.1 regarding bold face numbers.

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Figure 7.13 Performance comparison between present (option 3) and ideal (option 1) repair strategies of flood damage scenario 25

7.2.4 Flood damage scenario 26 The scenario was: ‘A flood damaged property has a PVC external door that has been in contact with floodwater’ as presented in Figure 7.14. Five repair choices were provided as follows: Option 1: Option 2: Option 3: Option 4: Option 5:

Recommend the door be replaced. Recommend the door be repainted. Allow the door to dry out and then assess the damage. Clean the door only. Recommend replacement of the glazing units if the seals have perished.

A reasonable number of respondents chose multiple strategies; therefore, two more options were established, representing combinations of the above options. They were defined as follows: Option 6: Allow the door to dry out and then assess the damage, before replacement of the glazing units if the seals have perished (options 3 and 5). Option 7: Clean the door and then replace the glazing units if the seals have perished (options 4 and 5). The respondents’ present repair strategies are depicted in Figure 7.15. Most respondents chose either options 3 (40.2%) or 4 (31.4%); some recommended options 5 (11.1%), 6 (8.4%) and 7 (7.7%); a few (1.1%) selected option 1, but none selected option 2, suggesting that this option is not a feasible strategy in

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Figure 7.14

Image of flood damage scenario 26

Figure 7.15

Present repair strategies for flood damage scenario 26

these circumstances. A comparison of the performance of these strategies is presented in Figure 7.16. Option 1 was not compared due to the small sample size. As expected, option 4 was the most cost effective strategy as confirmed by statistical tests (Table 7.4), whereas option 6 was the most costly. Options 6 and 7 provided higher quality and satisfaction, although these differences were not statistically significant. Option 6 was the quickest strategy to be implemented. Overall, option 4 was the best strategy; however, its superiority was only statistically confirmed when compared with options 3 and 5. Overall, options 4, 6 and 7 were found to deliver similar levels of performance. It is worth noting that there were no performance differences between options 5, 6 and 7, suggesting that these strategies yield similar levels of performance;

Reinstatement of Flood Damaged Doors and Windows

Figure 7.16 scenario 26

143

Performance comparison between repair strategies of flood damage

hence, damage assessors could employ any of these strategies without an impact on performance outcomes. Cleaning the door only (i.e. option 4) is the benchmark strategy for this scenario. Twenty-six of the 267 respondents (9.7%) would recommend an alternative ideal repair strategy (i.e. different to that presently used), as presented in Table 7.5. Option 1 was the most popular ideal repair strategy as selected by 53.8% of these respondents. Option 5 was the second most popular choice, being selected by 34.6% of respondents. No performance comparison was conducted due to the small sample size in each case (i.e. less than 10 responses in each cell in the matrix presented in Table 7.5).

Table 7.4 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 26 Repair strategy Option 3 Option 4 Option 5 Option 6

Option 4

Option 5

Option 6

Option 7

C,T,o

c C,o

C,t C

C

Note: Upper case indicates 99% confidence level; lower case indicates 95% confidence level. C or c, significant difference in cost performance; Q or q, significant difference in quality performance; T or t, significant difference in time performance; S or s, significant difference in expected percentage of satisfied clients; O or o, significant difference in overall performance.

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Table 7.5 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 26 Ideal strategy Present strategy Option 3

Option 1 4 57.1% 5 35.7% 2 100.0% 3 100.0%

Option 4 Option 5 Option 6 Column total

14 53.8%

Option 3

Option 5

Option 6

Row total

1 14.3%

2 14.3%

2 28.6% 7 50.0%

7 100.0% 14 100.0% 2 100.0% 3 100.0%

2 7.7%

9 34.6%

1 3.8%

26 100.0%

7.2.5 Flood damage scenario 27 The scenario was: ‘A flood damaged property has wooden window frames that have been in contact with floodwater’ as presented in Figure 7.17. Five repair strategy options were provided as follows:

Figure 7.17

Image of flood damage scenario 27

Reinstatement of Flood Damaged Doors and Windows

Option 1: Option 2: Option 3: Option 4: Option 5:

145

Recommend the windows be replaced. Recommend the windows be repainted. Allow the windows to dry out and then assess the damage. Clean the windows and frames only. Recommend replacement of the glazing units if the seals have perished.

A reasonable number of respondents chose multiple strategies; therefore, one more option was established, representing a combination of the above options. It was defined as follows: Option 6: Allow the windows to dry out and then assess the damage, before replacement of the glazing units if the seals have perished (options 3 and 5). Figure 7.18 depicts the respondents’ present repair strategies. The majority of the respondents (78.3%) recommended option 3, i.e. allow the windows to dry out and then assess the damage; 11.6% chose option 6, i.e. allow the windows to dry out and then assess the damage, before replacement of the glazing units if the seals have perished. Only a few recommended options 1 (3.1%), 2 (3.5%), 4 (1.9%) and 5 (1.6%). A comparison of the performance between options 3 and 6 is presented in Figure 7.19. Option 6 was better in all aspects except cost performance. However, only cost performance and satisfaction differences were confirmed statistically, indicating that option 6 delivers higher satisfaction but is more expensive than option 3. Allowing the windows to dry out and then assessing the damage, before replacement of the glazing units if the seals have perished is the benchmark strategy for this scenario. Thirty-eight of the 265 respondents (14.3%) recommended an alternative ideal strategy (i.e. different to that presently used), as presented in Table 7.6. Option 1 was an ideal strategy for most (89.5%) of these respondents. A performance comparison between present and ideal strategies is presented in Figure 7.20. Option 1 was the better strategy in all aspects except cost

Figure 7.18

Present repair strategies for flood damage scenario 27

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Figure 7.19 scenario 27

Performance comparison between repair strategies of flood damage

Table 7.6 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 27 Ideal strategy Present strategy

Option 1

Option 2

Option 1 Option 2 Option 3 Option 6 Column total

2 66.7% 24 92.3% 8 100.0%

2 7.7%

34 89.5%

2 5.3%

Option 3

Row total

1 100.0% 1 33.3%

1 100.0% 3 100.0% 26 100.0% 8 100.0%

2 5.3%

38 100.0%

Note: See Table 7.1 regarding bold face numbers.

performance, as confirmed statistically. This suggests that these respondents would have preferred to adopt a strategy which gave better performance, but that this was prohibitively expensive in their current employment.

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Figure 7.20 Performance comparison between present (option 3) and ideal (option 1) repair strategies of flood damage scenario 27

7.3

Summary This section provides a summary of the results for each scenario previously presented. Tables 7.7–7.11 present a summary of the response to each scenario. Current strategies are listed in descending order of popularity and ranked in terms of their performance (cost, quality, time, satisfaction and overall). For each scenario, a benchmark is provided based on the overall performance. Implications arising from these results are also discussed.

7.3.1 Scenario 23: ‘A flood damaged property has a softwood front door that has been in contact with floodwater’ A summary of the analysis for scenario 23 is presented in Table 7.7. The majority of the respondents (81.4%) recommended the door be allowed to dry out and then the damage be assessed, which was the most cost effective Table 7.7 Summary of the analysis for scenario 23: ‘A flood damaged property has a softwood wooden front door that has been in contact with floodwater’ Performance ranking Repair strategy Allow the door to dry out and then assess the damage Replace the door Repaint the door Clean the door only Note: C, cost; Q, quality; T, time; S, satisfaction; O, overall.

Chosen by (%)

C

Q

T

S

O

81.4 16.2 1.2 1.2

1 2 – –

2 1 – –

2 1 – –

2 1 – –

2 1 – –

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solution. Some (16.2%) recommended the door be replaced, which performed better in all aspects except cost performance. Although replacing the door delivered better quality and higher satisfaction, this option was chosen by significantly fewer respondents than those who allowed the door to dry out before assessing the damage. However, the overall performance scores indicate that the replacement of the door is the benchmark strategy for this scenario. Further analysis of ideal strategies revealed that increased cost was the primary consideration for not employing strategies which deliver a better quality repair and higher satisfaction.

7.3.2 Scenario 24: ‘A flood damaged property has double glazed hardwood patio doors that have been in contact with floodwater’ A summary of the analysis for scenario 24 is provided in Table 7.8. The majority of the respondents (75.7%) recommended the door be allowed to dry out and then the damage be assessed, which was the most cost effective solution. Some (16.3%) advocated allowing the door to dry out and then assessing the damage before replacement of the glazing units if the seals had perished; this performed better in all respects except cost, and is the benchmark solution for this scenario. This result highlights the need to make a thorough assessment of the situation before any repair decisions are made. It is worth noting the high number of respondents who recommended this strategy, even though it was not a standard option provided. The analysis of ideal strategies revealed replacement of the door to be the option most favoured. A comparison between present and ideal strategies indicated that the increased cost precluded the implementation of these ideal strategies. Table 7.8 Summary of the analysis for scenario 24: ‘A flood damaged property has double glazed hardwood patio doors that have been in contact with floodwater’ Performance ranking Repair strategy Allow the door to dry out and then assess the damage Allow the door to dry out and then assess the damage, before replacement of the glazing units if the seals have perished Clean the door only Replace the door Replace the glazing units if the seals have perished Repaint the door Note: See Table 7.7 for explanation of symbols.

Chosen by (%)

C

Q

T

S

O

75.7

1

2

2

2

2

16.3 3.2 2.4

2 – –

1 – –

1 – –

1 – –

1 – –

1.6 0.8

– –

– –

– –

– –

– –

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7.3.3 Scenario 25: ‘A flood damaged property has hollow cellular type infill wooden doors that have been in contact with floodwater’ Table 7.9 provides a summary of the analysis for scenario 25. Replacing the door was recommended by most respondents (78.8%). Some (20.8%) recommended the door be allowed to dry out and then the damage be assessed; this was the most cost effective solution. Replacing the door was better in all respects except cost performance. Although replacing the door was perceived to be more costly than allowing the door to dry out and then assessing the damage, it was preferred by most respondents, suggesting that cost is not the most important consideration when selecting strategies for this scenario. In sum, the replacement of the door is the benchmark solution for this scenario. Table 7.9 Summary of the analysis for scenario 25: ‘A flood damaged property has hollow cellular type infill wooden doors that have been in contact with floodwater’ Performance ranking Repair strategy Replace the door Allow the door to dry out and then assess the damage Clean the door only

Chosen by (%)

C

Q

T

S

O

78.8

2

1

1

1

1

20.8 0.4

1 –

2 –

2 –

2 –

2 –

Note: See Table 7.7 for explanation of symbols.

7.3.4 Scenario 26: ‘A flood damaged property has a PVC external door that has been in contact with floodwater’ Table 7.10 summarises the analysis for scenario 26. There was disparity in the respondents’ opinions regarding this scenario, with most recommending either allowing the door to dry out and then assessing the damage (40.2%) or cleaning the door only (31.4%). As expected, the latter solution was the most cost effective. Allowing the door to dry out and then assessing the damage, before replacement of the glazing units if the seals had perished delivered better quality and was the quickest strategy. The cleaning strategy was marginally slower. Cleaning the door and then replacing the glazing units if the seals had perished delivered higher satisfaction. Overall, the cleaning strategy was the most effective solution, although only marginally; it is the benchmark solution for this scenario. Deeper analysis revealed, surprisingly that all strategies delivered a similar level of quality and satisfaction. Therefore, cost is the main factor to be considered when selecting a strategy. Furthermore, the three strategies which involve the replacement of the glazing units if the seals have perished yielded similar performance in all respects.

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Table 7.10 Summary of the analysis for scenario 26: ‘A flood damaged property has a PVC external door that has been in contact with floodwater’ Performance ranking Repair strategy Allow the door to dry out and then assess the damage Clean the door only Replace the glazing units if the seals have perished Allow the door to dry out and then assess the damage, before replacement of the glazing units if the seals have perished Clean the door and then replace the glazing units if the seals have perished Replace the door

Chosen by (%)

C

Q

T

S

O

40.2 31.4

2 1

4 3

5 2

4 5

4 1

11.1

4

5

4

3

5

8.4

5

1

1

2

3

7.7 1.1

3 –

2 –

3 –

1 –

2 –

Note: See Table 7.7 for explanation of symbols.

7.3.5 Scenario 27: ‘A flood damaged property has wooden window frames that have been in contact with floodwater’ The analysis for scenario 27 is summarised in Table 7.11. Most respondents (78.3%) recommended the windows be allowed to dry and then the damage be assessed (option 3), which was the most cost effective solution. Allowing the windows to dry out and then assessing the damage, before replacement of the glazing units if the seals have perished (option 6), as recommended by 11.6% of respondents performed better in all aspects except cost. These results Table 7.11 Summary of the analysis for scenario 27: ‘A flood damaged property has wooden window frames that have been in contact with floodwater’ Performance ranking Repair strategy Allow the windows to dry out and then assess the damage Allow the windows to dry out and then assess the damage, before replacement of the glazing units if the seals have perished Repaint the windows Replace the windows Clean the windows and frames only Replace glazing units if the seals have perished Note: See Table 7.7 for explanation of symbols.

Chosen by (%)

C

Q

T

S

O

78.3

1

2

2

2

2

11.6 3.5 3.1 1.9 1.6

2 – – – –

1 – – – –

1 – – – –

1 – – – –

1 – – – –

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suggest the importance of a thorough examination before selecting an appropriate repair strategy. Further analysis revealed that the differences between strategies 3 and 6 in quality, time and overall performance were marginal. Allowing the windows to dry out and then assessing the damage, before replacement of the glazing units if the seals had perished, delivers higher satisfaction levels but was more expensive than allowing the windows to dry out and then assessing the damage. The analysis of ideal strategies revealed that replacing the windows was the favourite ideal strategy. A comparison between present and ideal strategies suggests that respondents would have adopted a strategy which delivered better performance, but this was prohibitively expensive. In summary, the overall performance suggests that allowing the windows to dry out and then assessing the damage, before the replacement of the glazing units if the seals have perished is the benchmark solution for this scenario. The next chapter will discuss the reinstatement of flood damaged utilities.

8

8.1

Reinstatement of Flood Damaged Utilities and Fittings Introduction This chapter presents the assessment of flood damaged domestic utilities (e.g. heating, gas, electrical systems, staircases and kitchens) commonly found in domestic properties. Ten scenarios are presented; this is followed by a discussion of the remedial solutions indicated by the respondents, including their perceived performance. First, the results and analysis are presented, followed by a detailed discussion of the findings. Finally, a summary and a discussion of the implications of the findings are presented.

8.2

Results and discussion For each scenario, the digital image and the repair strategy options are first presented. Then, the respondents’ present strategies are presented and discussed, followed by a comparative analysis between the strategies. Preferences for ideal strategies are then presented and discussed. A comparison of the performance of these ideal strategies with those of current practice is then given.

8.2.1 Flood damage scenario 28 The scenario was: ‘A flood damaged property has steel panel radiators installed that have been in contact with floodwater’ as presented in Figure 8.1. Three repair strategy options were provided as follows: Option 1: Recommend the radiator and valves be replaced. Option 2: Recommend the radiator valves be replaced. Option 3: Recommend the radiator be left alone. A reasonable number of respondents recommended a different strategy to those provided; therefore, one more option was established. It was defined as follows: Option 4: Allow the radiator to dry, clean/sanitise, and then repaint. 152

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Figure 8.1

153

Image of flood damage scenario 28

Figure 8.2 shows the respondents’ present repair strategies. The opinions of the respondents regarding this damage scenario were diverse: 40.2% recommended option 3, 24.3% chose option 2, 22.7% selected option 4, and 12.7% recommended option 1. A comparison of the performance of the different strategies is presented in Figure 8.3. As expected, option 3 was the most cost effective and quickest strategy to be implemented, as confirmed by statistical tests (Table 8.1). Although option 1 was the most costly strategy, it delivered a higher quality repair and greater satisfaction. Option 4 was the second most effective strategy in terms of quality and satisfaction. Overall, options 3 and 4 provided the same high level of performance. Option 4 delivered better quality and higher satisfaction, but was more expensive and took longer to

Figure 8.2

Present repair strategies for flood damage scenario 28

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Figure 8.3 Performance comparison between repair strategies of flood damage scenario 28

complete than option 3. Nevertheless, allowing the radiator to dry, cleaning/ sanitising, and then repainting (i.e. option 4) is considered the benchmark strategy for this scenario. Fifty-two of the 266 respondents (19.5%) recommended an alternative ideal repair strategy (i.e. an option different from that presently used). Option 1 was mostly (61.5%) chosen by these respondents (Table 8.2), but option 2 was selected by 36.5%. Performance comparisons were conducted in several cases as presented in Figures 8.4–8.6. A comparison between options 2 (present strategy) and 1 (ideal strategy) revealed that option 1 was better in all aspects except cost performance; these differences, with the exception of time performance, were confirmed by statistical tests. A comparison between options 3 (present strategy) and 1 (ideal strategy) revealed that option 1 delivered significantly better quality and satisfaction, whereas option 3 was

Table 8.1 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 28 Repair strategy Option 1 Option 2 Option 3

Option 2

Option 3

Option 4

C,q,S

C,Q,T,S C,T,O

C,S O C,q,T,S

Note: Upper case indicates 99% confidence level; lower case indicates 95% confidence level. C or c, significant difference in cost performance; Q or q, significant difference in quality performance; T or t, significant difference in time performance; S or s, significant difference in expected percentage of satisfied clients; O or o, significant difference in overall performance.

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Table 8.2 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 28 Ideal strategy Present strategy

Option 1

Option 1 Option 2 Option 3 Option 4 Column total

Option 2

Option 4

1 100.0% 11 100.0% 15 46.9% 6 75.0%

16 50.0% 2 25.0%

1 3.1%

32 61.5%

19 36.5%

1 1.9%

Row total 1 100.0% 11 100.0% 32 100.0% 8 100.0% 52 100.0%

Note: Bold face indicates that the ‘quantity’ is sufficient for further statistical comparison (defined as at least 10).

much less expensive and was also quicker to implement. Overall, option 3 was better as it balanced cost and time with quality and satisfaction; however, this was not confirmed statistically. A similar tendency was found in the comparison between option 3 (present strategy) and option 2 (ideal strategy). Here, only the differences in cost performance and satisfaction were confirmed statistically. Generally, ideal strategies delivered better quality and higher satisfaction but cost more and, occasionally, took longer to implement.

Figure 8.4 Performance comparison between present (option 2) and ideal (option 1) repair strategies of flood damage scenario 28

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Figure 8.5 Performance comparison between present (option 3) and ideal (option 1) repair strategies of flood damage scenario 28

Figure 8.6 Performance comparison between present (option 3) and ideal (option 2) repair strategies of flood damage scenario 28

8.2.2 Flood damage scenario 29 The scenario was: ‘A flood damaged property has a gas fired heater that has been in contact with floodwater’ as presented in Figure 8.7. Three repair strategy choices were provided as follows:

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Option 1: Recommend the heater be serviced. Option 2: Recommend the heater be replaced. Option 3: Recommend the heater be fitted with new controls. A reasonable number of respondents recommended a different strategy to those provided; therefore, one more option was established. This was defined as follows: Option 4: Inspection and report by specialists (e.g. Corgi engineers).

Figure 8.7

Image of flood damage scenario 29

The respondents’ present repair strategies are presented in Figure 8.8. The opinions of respondents were mainly divided into two groups, with option 1 being chosen by 45.5% and option 2 by 46.2%. Some (6.4%) recommended option 4 and a few (1.9%) chose option 3. A comparison of the performance of the strategies is presented in Figure 8.9. Option 2 was the most effective in all aspects except cost performance because it was the most costly strategy; option 1 was the most cost effective strategy. There was no significant difference in time performance (Table 8.3) and therefore when selecting repair strategy, cost, quality and satisfaction should be taken into account. Statistical tests revealed no performance difference between options 1 and 4, suggesting that both strategies are similar and produce similar performance outcomes. Overall performance scores indicate that the replacement of the heater (i.e. option 2) is the benchmark solution for this scenario. Of the 267 experts who responded to this scenario, 46 (17.2%) recommended an alternative ideal strategy (i.e. one different from that presently

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Figure 8.8

Present repair strategies for flood damage scenario 29

Figure 8.9 Performance comparison between repair strategies of flood damage scenario 29

used), as presented in Table 8.4; for the majority of those (91.3%) option 2 was the ideal strategy. A performance comparison between options 1 (present strategy) and 2 (ideal strategy) shown in Figure 8.10 revealed that option 2 was better in all aspects except cost performance. All differences, with the exception of time performance, were confirmed statistically, indicating Table 8.3 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 29 Repair strategy

Option 2

Option 1 Option 2

C,Q,S,O

Note: See Table 8.1 for explanation of symbols.

Option 4 C,q,S

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Table 8.4 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 29 Ideal strategy Present strategy

Option 1

Option 2

Option 3

Row total

38 97.4%

1 2.6%

39 100.0% 3 100.0% 2 100.0% 2 100.0%

1 2.2%

46 100.0%

Option 1 Option 2

3 100.0%

Option 3

2 100.0% 2 100.0%

Option 4 Column total

3 6.5%

42 91.3%

Note: See Table 8.2 regarding bold face numbers.

Figure 8.10 Performance comparison between present (option 1) and ideal (option 2) repair strategies of flood damage scenario 29

that these respondents would have preferred to employ a strategy which delivered better quality and satisfaction, but that this was prohibitively expensive.

8.2.3 Flood damage scenario 30 The scenario was: ‘A flood damaged property has a gas meter that has been in contact with floodwater’

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as presented in Figure 8.11. Three repair strategy options were provided as follows: Option 1: Recommend the meter be replaced. Option 2: Recommend the meter be checked for leaks. Option 3: Recommend the connections to the meter be made again. A reasonable number of respondents recommended a strategy different from those provided; therefore, one more option was established. This was defined as follows: Option 4: Refer to gas supplier.

Figure 8.11

Image of flood damage scenario 30

The respondents’ present repair strategies are presented in Figure 8.12; 54.7% recommended option 2, i.e. check the meter for leaks, whereas 25.0% chose option 1, 16.0% selected option 4 and 4.3% chose option 3. A comparison of the performance of the strategies is presented in Figure 8.13. Option 3 was the most cost effective strategy but delivered poorer performance in the other respects. Option 1 was the most costly strategy, as confirmed by statistical tests (Table 8.5). Options 1 and 4 yielded a higher quality repair. Option 2 was the quickest strategy to be implemented, although the difference was not statistically significant; thus the time required to implement all strategies is approximately the same. Option 1 yielded the highest satisfaction, followed by option 4. Overall, option 4 was the most effective strategy, as confirmed by statistical tests (Table 8.5), and hence provides the benchmark solution for this scenario. Twenty-five of the 257 respondents (9.7%) recommended an alternative ideal strategy, as presented in Table 8.6. Option 1 was the most popular

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Figure 8.12

Present repair strategies for flood damage scenario 30

Figure 8.13 scenario 30

Performance comparison between repair strategies of flood damage

Table 8.5 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 30 Repair strategies Option 1 Option 2 Option 3

Option 2

Option 3

Option 4

C,Q,S

C,Q,S,o q

C,S,o Q,s,o Q,s,O

Note: See Table 8.1 for explanation of symbols.

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Table 8.6 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 30 Ideal strategy Present strategy

Option 1

Option 2

Option 1 Option 2 Option 3 Column total

Option 3

Row total

2 9.5%

1 100.0% 21 100.0% 3 100.0%

2 8.0%

25 100.0%

1 100.0% 19 90.5% 3 100.0% 22 88.0%

1 4.0%

Note: See Table 8.2 regarding bold face numbers.

Figure 8.14 Performance comparison between present (option 2) and ideal (option 1) repair strategies of flood damage scenario 30

strategy, being selected by a large majority (88.0%) of these respondents. The performance comparison between options 2 (present strategy) and 1 (ideal strategy) presented in Figure 8.14 revealed that option 1 produced better performance in all respects except cost. Statistical tests confirmed the differences in cost, quality, satisfaction and overall performance; however, there was no significant difference in time performance. The results suggest a desire to employ a strategy which produces a better quality repair and higher satisfaction, but this is prohibitively expensive.

8.2.4 Flood damage scenario 31 The scenario was: ‘A flood damaged property has a wall-hung gas fire that has been in contact with floodwater’

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as presented in Figure 8.15. Three repair strategy options were provided as follows: Option 1: Recommend the fire be serviced. Option 2: Recommend the fire be replaced. Option 3: Recommend the fire be fitted with new controls. A reasonable number of respondents recommended a strategy different from those provided; therefore, one more option was established. This was defined as follows: Option 4: Inspection and report by specialists (qualified gas engineers).

Figure 8.15

Image of flood damage scenario 31

The respondents’ present repair strategies are presented in Figure 8.16. Almost all respondents recommended either options 1 (51.7%) or 2 (41.1%), with few recommending options 3 (1.5%) and 4 (5.7%). Figure 8.17 presents a comparison of the performance of these strategies. Option 2 was the most effective in all aspects except cost performance. Options 1 and 4 were the two most cost effective strategies and there were no significant performance differences between them (Table 8.7), suggesting that both yield similar outcomes. Statistical tests confirmed no difference in time performance between strategies 1 and 4, suggesting that the time required to implement them is approximately the same. The overall performance indicates that the replacement of the fire (i.e. option 2) is the benchmark solution for this scenario.

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Figure 8.16

Present repair strategies for flood damage scenario 31

Figure 8.17 scenario 31

Performance comparison between repair strategies of flood damage

Of the 264 respondents who responded to this scenario, 44 (16.7%) recommended an alternative ideal strategy, as presented in Table 8.8. Most of these respondents (88.6%) recommended option 2 as their ideal repair strategy. A performance comparison between options 1 (present strategy) and 2 (ideal strategy) as presented in Figure 8.18, revealed that option 2 was better Table 8.7 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 31 Repair strategy

Option 2

Option 1 Option 2

C,Q,S,O

Note: See Table 8.1 for explanation of symbols.

Option 4 C,S

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Table 8.8 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 31 Ideal strategy Present strategy

Option 1

Option 2

Option 3

Row total

34 94.4%

2 5.6%

36 100.0% 3 100.0% 2 100.0% 3 100.0%

2 4.5%

44 100.0%

Option 1 Option 2

3 100.0%

Option 3

2 100.0% 3 100.0%

Option 4 Column total

3 6.8%

39 88.6%

Note: See Table 8.2 regarding bold face numbers.

Figure 8.18 Performance comparison between present (option 1) and ideal (option 2) repair strategies of flood damage scenario 31

in all aspects except cost. All performance differences were confirmed statistically. This suggests that the high cost of certain strategies precludes their implementation.

8.2.5 Flood damage scenario 32 The scenario was: ‘The dwelling has an electrical circuit containing sockets and cables which have been partly submerged by floodwater’

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as presented in Figure 8.19. Three repair strategy options were provided as follows: Option 1: Recommend complete replacement of this installation. Option 2: Recommend replacement of electrical wiring and fittings installed below the floodline. Option 3: Recommend electrical circuit be checked by an electrician and any faults rectified.

Figure 8.19

Image of flood damage scenario 32

Figure 8.20 shows the respondents’ present repair strategies. Most respondents (71.1%) recommended option 3; 20.3% opted for option 2 and 8.6% recommended option 1. A comparison of the performance of these strategies is presented in Figure 8.21. Although option 1 was the most costly strategy, it delivered better performance in all other aspects. Statistical tests revealed no time performance differences between the strategies (Table 8.9), suggesting that the time required to implement these strategies is approximately the same. Apart from cost performance, there was no significant difference between options 2 and 3, suggesting that both strategies produced the same levels of quality and satisfaction and took the same time to be implemented. Here, option 3 may be preferred because it was cheaper. Although option 1 provided better quality and higher satisfaction, it was chosen by only a few respondents because of its high cost. Nonetheless, the overall performance suggests that the complete replacement of the installation (i.e. option 1) is the benchmark strategy for this scenario.

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Figure 8.20

Present repair strategies for flood damage scenario 32

Figure 8.21 scenario 32

Performance comparison between repair strategies of flood damage

Table 8.9 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 32 Repair strategy Option 1 Option 2

Option 2

Option 3

q,S,O

C,Q,S,O C

Note: See Table 8.1 for explanation of symbols.

Of the 262 respondents who responded to this scenario, 48 (18.3%) recommended an alternative ideal strategy as presented in Table 8.10. Option 2 was the most popular strategy chosen by 54.2% of these respondents, followed closely by option 1 which was chosen by 43.8%. Those respondents who initially chose option 3, recommended either options 1 or 2 as their ideal

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Table 8.10 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 32 Ideal strategy Present strategy

Option 1

Option 2

Option 1 Option 2 Option 3 Column total

Option 3

Row total

1 12.5%

1 100.0% 8 100.0% 39 100.0%

1 2.1%

48 100.0%

1 100.0% 7 87.5% 14 35.9%

25 64.1%

21 43.8%

26 54.2%

Note: See Table 8.2 regarding bold face numbers.

strategies. Performance comparisons between present and ideal strategies are presented in Figures 8.22 and 8.23. A performance comparison between options 3 (present strategy) and 1 (ideal strategy) revealed that option 1 delivered higher quality and satisfaction but was inferior in cost, time and overall performance; statistical tests confirmed the differences in cost and satisfaction. A similar tendency was found in the comparison between options 3 (present strategy) and 2 (ideal strategy); here, statistical tests confirmed the differences in cost, quality, time and satisfaction. Ideal strategies delivered higher quality and satisfaction; however, they were more costly and took longer to implement, which precluded their use.

Figure 8.22 Performance comparison between present (option 3) and ideal (option 1) repair strategies of flood damage scenario 32

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Figure 8.23 Performance comparison between present (option 3) and ideal (option 2) repair strategies of flood damage scenario 32

8.2.6 Flood damage scenario 33 The scenario was: ‘The dwelling has a wall-hung electrical heater that has been submerged by floodwater’ as presented in Figure 8.24. Three repair strategy choices were provided as follows:

Figure 8.24

Image of flood damage scenario 33

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Option 1: Recommend the heater be replaced. Option 2: Recommend the heater be left alone. Option 3: Recommend that the heater be checked by an electrician. Figure 8.25 shows the respondents’ present repair strategies; their opinions were divided into two almost equal proportions, with 51.1% choosing option 1 and 48.9% option 3. None chose option 2, suggesting that leaving the heater alone is not a feasible strategy. A performance comparison between options 1 and 3 as shown in Figure 8.26, revealed that option 1 was the better strategy in all respects except cost performance; except for time performance, these differences were confirmed by statistical tests. This indicates that option 1 delivered higher quality, satisfaction and overall performance, but was more expensive than option 3; the time required was perceived to be approximately the same. In sum, the replacement of the heater (i.e. option 1) is the benchmark solution for this strategy.

Figure 8.25

Present repair strategies for flood damage scenario 33

Figure 8.26 scenario 33

Performance comparison between repair strategies of flood damage

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Table 8.11 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 33 Ideal strategy Present strategy

Option 1

Option 3

Row total

3 100.0%

3 100.0% 29 100.0%

3 9.4%

32 100.0%

Option 1 Option 3

29 100.0%

Column total

29 90.6%

Note: See Table 8.2 regarding bold face numbers.

Of the 264 respondents who responded to this scenario, 32 (12.1%) indicated an alternative ideal strategy, as presented in Table 8.11. The vast majority (90.6%) of these respondents recommended option 1 as their ideal strategy. A comparison of the performance of options 3 (present strategy) and 1 (ideal strategy) is presented in Figure 8.27. Option 1 performed better in all respects except cost performance, as confirmed statistically. These results indicate that respondents would prefer to adopt a strategy which delivered higher quality and satisfaction and was quicker to implement; however, this was precluded by the expense involved.

Figure 8.27 Performance comparison between present (option 3) and ideal (option 1) repair strategies of flood damage scenario 33

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8.2.7 Flood damage scenario 34 The scenario was: ‘The dwelling has timber skirting boards’ as presented in Figure 8.28. Four repair strategy options were provided as follows: Option 1: Recommend replacement of all skirting boards. Option 2: Recommend replacement of skirting boards that are damaged by the floodwater. Option 3: Allow skirting boards to dry and recommend replacement of damaged sections of board. Option 4: Leave existing skirting board in place.

Figure 8.28

Image of flood damage scenario 34

The respondents’ present repair strategies are presented in Figure 8.29. There was disparity of opinion regarding this scenario with respondents being divided into three almost equal groups: option 1 (32.2%), option 2 (29.5%) and option 3 (37.9%). Option 4 was chosen by only one respondent, suggesting that leaving the existing skirting board in place is not a feasible strategy. A comparison of the performance of these strategies is presented in Figure 8.30. Option 1 was the most effective strategy in all respects except cost performance. Option 3 was the most cost effective strategy but performed poorly in all other aspects. The performance of option 2 was intermediate between options 1 and 3. There was no significant time performance difference between options 1 and 2 (Table 8.12), suggesting that the time required to replace all skirting boards and to replace skirting boards damaged by the

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Figure 8.29

Present repair strategies for flood damage scenario 34

Figure 8.30 scenario 34

Performance comparison between repair strategies of flood damage

Table 8.12 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 34 Repair strategy

Option 2

Option 3

Option 1 Option 2

C,Q,S,O

C,Q,t,S,O q,S,O

Note: See Table 8.1 for explanation of symbols.

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Table 8.13 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 34 Ideal strategy Present strategy

Option 1

Option 2

Option 3

Row total

1 50.0%

1 50.0% 1 8.3%

2 100.0% 12 100.0% 33 100.0%

2 4.3%

47 100.0%

Option 1 Option 2 Option 3 Column total

11 91.7% 26 78.8%

7 21.2%

37 78.7%

8 17.0%

Note: See Table 8.2 regarding bold face numbers.

floodwater was approximately the same. There were no significant cost and time performance differences between options 2 and 3. Here, option 2 may be preferred because of the higher quality, satisfaction and overall performance delivered. In summary, the replacement of all skirting boards (i.e. option 1) is the benchmark solution for this scenario. Of the 267 experts who responded to this scenario, 47 (17.6%) indicated an alternative ideal strategy, as presented in Table 8.13. Option 1 was selected by 78.7% of these respondents. Performance comparisons between present and ideal strategies are presented in Figures 8.31 and 8.32. A performance comparison between options 2 (present strategy) and 1 (ideal strategy) revealed that option 1 yielded higher quality and satisfaction, as confirmed by statistical tests, but was more expensive and time consuming. Overall, option 1 was

Figure 8.31 Performance comparison between present (option 2) and ideal (option 1) repair strategies of flood damage scenario 34

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Figure 8.32 Performance comparison between present (option 3) and ideal (option 1) repair strategies of flood damage scenario 34

slightly better than option 2. A performance comparison between options 3 (present strategy) and 1 (ideal strategy) revealed that option 1 was better in all respects except cost performance. With the exception of time performance, all differences were confirmed statistically. This suggests that the time required to implement strategies 3 and 1 is approximately the same. Generally, ideal strategies delivered a higher quality repair and greater satisfaction, but were more costly which precluded their present use.

8.2.8 Flood damage scenario 35 The scenario was: ‘The dwelling has a staircase constructed from timber’ as presented in Figure 8.33. Four repair strategy options were provided as follows: Option 1: Recommend complete replacement of the staircase. Option 2: Recommend replacement of timber components that have been in contact with floodwater. Option 3: Recommend the stairs be allowed to dry and then assess any damage caused. Option 4: Recommend the stairs be left alone. The respondents’ present repair strategies are presented in Figure 8.34. Almost all respondents (89.6%) recommended option 3, i.e. to allow the stairs to dry and then assess any damage caused. Some (8.8%) chose option 2; very few chose options 1 (1.2%) and 4 (0.4%).

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Figure 8.33

Image of flood damage scenario 35

Figure 8.34

Present repair strategies for flood damage scenario 35

Figure 8.35 presents a comparison of the performance of the strategies. Options 1 and 4 were excluded due to their small sample sizes. Option 2 produced a higher quality repair and greater satisfaction, as confirmed by statistical tests, but was more expensive. Overall, option 2 was slightly better than option 3. Statistical tests revealed no differences in time or overall performance. Nonetheless, the replacement of timber components that have been in contact with floodwater (i.e. option 2) is considered the benchmark solution for this scenario. Forty-six of the 262 respondents (17.6%) indicated an alternative repair strategy, as presented in Table 8.14. Option 2 was the most favoured ideal strategy and was chosen by 60.9% of these respondents, whilst option 1 was chosen by 34.8%. Performance comparisons between present and ideal strategies are presented in Figures 8.36 and 8.37. A performance comparison

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Figure 8.35 scenario 35

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Performance comparison between repair strategies of flood damage

Table 8.14 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 35 Ideal strategy Present strategy Option 2 Option 3 Column total

Option 1

Option 2

1 33.3% 15 34.9%

28 65.1%

16 34.8%

28 60.9%

Option 3

Row total

2 66.7%

3 100.0% 43 100.0%

2 4.3%

46 100.0%

Note: See Table 8.2 regarding bold face numbers.

Figure 8.36 Performance comparison between present (option 3) and ideal (option 1) repair strategies of flood damage scenario 35

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Figure 8.37 Performance comparison between present (option 3) and ideal (option 2) repair strategies of flood damage scenario 35

between options 3 (present strategy) and 1 (ideal strategy) revealed that option 1 was better in quality, time and satisfaction; however, it was much more expensive than option 3. Overall, option 3 was slightly better. Statistical tests confirmed the performance differences in cost and satisfaction, suggesting that both strategies required the same time to be implemented and produced similar levels of quality and overall performance. A performance comparison between options 3 (present strategy) and 2 (ideal strategy) revealed that option 2 was better in all respects except cost performance. Statistical tests confirmed the performance differences in cost, quality and satisfaction, suggesting that the time required and overall performance produced are the same for both strategies. Generally, increased cost was the primary reason for not employing a strategy which delivered higher quality and satisfaction.

8.2.9 Flood damage scenario 36 The scenario was: ‘The dwelling has built-in wall cupboards’ as presented in Figure 8.38. Four repair strategy options were provided as follows: Option 1: Recommend complete replacement of the cupboards. Option 2: Recommend replacement of timber components that have been in contact with floodwater. Option 3: Recommend the cupboards be allowed to dry and then assess any damage caused. Option 4: Recommend the cupboards be left alone.

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Figure 8.38

179

Image of flood damage scenario 36

The respondents’ present repair strategies are presented in Figure 8.39. A majority (65.5%) recommended option 3, i.e. allow the cupboards to dry and assess any damage caused; 25.2% chose option 1 and 9.3% recommended option 2, but none recommended option 4, suggesting that leaving the cupboards alone is not a feasible strategy in these circumstances. A comparison of the performance of the strategies is presented in Figure 8.40. Option 1 was the most effective strategy in all respects except cost performance. With the exception of time performance, these differences were confirmed by statistical tests (Table 8.15). Option 3 was the most cost effective strategy. Statistical tests revealed no significant time performance differences between all strategies. Options 2 and 3 exhibited significant performance differences in cost alone, as confirmed by statistical tests; thus both strategies delivered the same level

Figure 8.39

Present repair strategies for flood damage scenario 36

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Figure 8.40 scenario 36

Performance comparison between repair strategies of flood damage Table 8.15 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 36 Repair strategy

Option 2

Option 3

Option 1 Option 2

C,Q,S,O

C,Q,S,O C

Note: See Table 8.1 for explanation of symbols.

Table 8.16 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 36 Ideal strategy Present strategy Option 2 Option 3 Column total

Option 1

Option 2

Row total

8 100.0% 31 73.8%

11 26.2%

8 100.0% 42 100.0%

39 78.0%

11 22.0%

50 100.0%

Note: See Table 8.2 regarding bold face numbers.

of quality, satisfaction and overall performance, and required the same time to be implemented. In sum, the complete replacement of the cupboards (i.e. option 1) is the benchmark strategy for this scenario. Fifty of the 261 respondents (19.2%) indicated an alternative ideal repair strategy, as presented in Table 8.16. Most (78.0%) recommended option 1 as an ideal strategy; the remainder (22.0%) recommended option 2. Performance

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comparisons between present and ideal strategies are presented in Figures 8.41 and 8.42. A performance comparison between options 3 (present strategy) and 1 (ideal strategy) revealed that option 1 was better in all respects except cost. Only differences in time performance were not statistically confirmed. A performance comparison between options 3 (present strategy) and 2 (ideal strategy) revealed option 2 to be better in all respects except cost. Statistical tests confirmed the differences in cost, quality and satisfaction, whereas the differences in time and overall performance were marginal. Generally, increased cost was the main reason for not employing a strategy which delivered higher quality and satisfaction.

Figure 8.41 Performance comparison between present (option 3) and ideal (option 1) repair strategies of flood damage scenario 36

Figure 8.42 Performance comparison between present (option 3) and ideal (option 2) repair strategies of flood damage scenario 36

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8.2.10 Flood damage scenario 37 The scenario was: ‘The dwelling has a ‘‘fitted’’ kitchen that has been partially submerged above the plinths by floodwater’ as presented in Figure 8.43. Three repair strategy options were provided as follows: Option 1: Recommend replacement of the complete kitchen. Option 2: Recommend replacement of those units that have been in contact with floodwater. Option 3: Allow the units to dry out and replace only those kitchen unit panels that have been damaged.

Figure 8.43

Image of flood damage scenario 37

The respondents’ present repair strategies are presented in Figure 8.44. Their opinions were quite disparate, with most respondents recommending either options 2 (43.7%) or 3 (39.5%) and quite a considerable number (16.9%) option 1. A comparison of the performance of these strategies is presented in Figure 8.45. Option 1 was the most effective in quality, satisfaction and overall performance as confirmed by statistical tests (Table 8.17). There were significant differences in cost performance of these three strategies (Table 8.17), with option 3 being the most cost effective and option 1 the most costly. However, there were no differences in the time required to implement these strategies. Interestingly, statistical tests revealed that there were no performance differences between options 2 and 3, except in cost where option 3 was more cost

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Figure 8.44

Present repair strategies for flood damage scenario 37

Figure 8.45 scenario 37

Performance comparison between repair strategies of flood damage Table 8.17 Matrix presenting the results of statistical tests for performance differences between repair strategies for flood damage scenario 37 Repair strategy

Option 2

Option 3

Option 1 Option 2

C,Q,S,O

C,Q,S,O C

Note: See Table 8.1 for explanation of symbols.

effective and therefore may be preferred. In sum, the complete replacement of the kitchen (i.e. option 1) is the benchmark solution for this scenario. Of the 267 respondents who responded to the scenario, 79 (29.6%) indicated an alternative repair strategy, as presented in Table 8.18. A majority (73.4%) recommended option 1 as their ideal repair strategy. Performance comparisons

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Table 8.18 Classification of respondents based on their present and ideal repair strategies for flood damage scenario 37 Ideal strategy Present strategy

Option 1

Option 2

Option 1 Option 2 Option 3 Column total

Option 3

Row total

1 2.5%

1 100.0% 40 100.0% 38 100.0%

1 1.3%

79 100.0%

1 100.0% 39 97.5% 19 50.0%

19 50.0%

58 73.4%

20 25.3%

Note: See Table 8.2 regarding bold face numbers.

between present and ideal strategies are presented in Figures 8.46–8.48. A performance comparison between options 2 (present strategy) and 1 (ideal strategy) revealed that option 1 was better in quality, satisfaction and overall performance; option 2 was more cost effective. All differences except those in time performance were confirmed statistically. A similar tendency was found in the performance comparison between options 3 (present strategy) and 1 (ideal strategy); option 1 performed better in quality, satisfaction and overall performance, whilst option 3 was better in cost and time performance. However, statistical tests confirmed the differences only in cost and satisfaction. A performance comparison between options 3 (present strategy) and 2 (ideal strategy) revealed that option 2 performed most effectively in all respects except cost. Statistical tests confirmed all these differences except for time

Figure 8.46 Performance comparison between present (option 2) and ideal (option 1) repair strategies of flood damage scenario 37

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Figure 8.47 Performance comparison between present (option 3) and ideal (option 1) repair strategies of flood damage scenario 37

Figure 8.48 Performance comparison between present (option 3) and ideal (option 2) repair strategies of flood damage scenario 37

performance. Generally, these results suggest that respondents would have preferred strategies which delivered higher quality and greater satisfaction, but that these were precluded because of the increased costs involved.

8.3

Summary This section provides a summary of the results for each scenario previously presented. Tables 8.19–8.28 present a summary of the response to each scenario. Current strategies are listed in descending order of popularity and ranked in

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terms of their performance (cost, quality, time, satisfaction and overall performance). For each scenario, a benchmark is provided based on the overall performance. Implications arising from these results are also discussed.

8.3.1 Scenario 28: ‘A flood damaged property has steel panel radiators installed that have been in contact with floodwater’ A summary of the analysis for scenario 28 is provided in Table 8.19. There was no consensus regarding the most appropriate repair strategy for this scenario: 40.2% of respondents recommended the radiator be left alone, which as expected, is the most cost effective and quickest strategy; 24.3% recommended the radiator valves be replaced and 22.7% recommended the radiator be allowed to dry, be cleaned/sanitised, and then repainted. It is worth noting that the number of respondents who recommended this last strategy was relatively large considering that it was not included in the list of original options. Some respondents (12.7%) recommended the radiator and valves be replaced; this provides higher quality and satisfaction. Further analysis on present and ideal strategies suggested that the increased cost involved was the principal reason for not employing strategies which delivered higher quality and satisfaction. This can also be inferred from the results as presented in Table 8.19, in that leaving the radiator alone was chosen by many more respondents than replacing the radiator and valves. In sum, allowing the radiator to dry, cleaning/sanitising and then repainting is the benchmark solution for this scenario. Table 8.19 Summary of the analysis for scenario 28: ‘A flood damaged property has steel panel radiators installed that have been in contact with floodwater’ Performance ranking Repair strategy Leave the radiator alone Replace the radiator valves Allow the radiator to dry, clean/sanitise and then repaint Replace the radiator and valves

Chosen by (%)

C

Q

T

S

O

40.2 24.3

1 3

4 3

1 4

4 3

1 4

22.7 12.7

2 4

2 1

2 3

2 1

1 3

Note: C, cost; Q, quality; T, time; S, satisfaction; O, overall.

8.3.2 Scenario 29: ‘A flood damaged property has a gas fired heater that has been in contact with floodwater’ A summary of the analysis for scenario 29 is presented in Table 8.20. The preferences of the respondents were mainly divided into two strategies, with 46.2% recommending replacing the heater and 45.5% servicing the heater.

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Table 8.20 Summary of the analysis for scenario 29: ‘A flood damaged property has a gas fired heater that has been in contact with floodwater’ Performance ranking Repair strategy Replace the heater Service the heater Inspection and report by specialists (Corgi engineers) Fit the heater with new controls

Chosen by (%)

C

Q

T

S

O

46.2 45.5

3 1

1 3

1 3

1 3

1 3

6.4 1.9

2 –

2 –

2 –

2 –

2 –

Note: See Table 8.19 for explanation of symbols.

Replacing the heater provided better performance in all respects except cost; servicing the heater was the most cost effective strategy. Few respondents (6.4%) advocated an inspection and report by specialists. Further analysis revealed that the time required to implement these strategies was approximately the same. Moreover, servicing the heater delivered a similar level of performance as inspection and report by specialists. Replacing the heater was chosen as an ideal strategy by almost all respondents who recommended an alternative strategy. Here, it yielded higher quality and satisfaction but at higher cost. In summary, replacement of the heater is the benchmark solution for this scenario.

8.3.3 Scenario 30: ‘A flood damaged property has a gas meter that has been in contact with floodwater’ Table 8.21 provides a summary of the analysis for scenario 30. More than half of the respondents (54.7%) recommended the meter be checked for leaks, which was the quickest strategy; 25.0% recommended the meter be replaced, which provided higher satisfaction; 16.0% recommended referral to a gas supplier, which delivered higher quality and overall performance. Few reTable 8.21 Summary of the analysis for scenario 30: ‘A flood damaged property has a gas meter that has been in contact with floodwater’ Performance ranking Repair strategy Check the meter for leaks Replace the meter Refer to gas supplier Make the connections to the meter again Note: See Table 8.19 for explanation of symbols.

Chosen by (%)

C

Q

T

S

O

54.7 25.0 16.0 4.3

3 4 2 1

3 2 1 4

1 3 2 4

3 1 2 4

3 2 1 4

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spondents (4.3%) recommended that the connections to the meter be made again, which was the most cost effective solution, although its performance in all other respects was quite poor. Further analysis revealed that the time required to implement these strategies is approximately the same. In sum, referral to a gas supplier is the benchmark solution for this scenario.

8.3.4 Scenario 31: ‘A flood damaged property has a wall-hung gas fire that has been in contact with floodwater’ Table 8.22 presents a summary of the analysis for scenario 31. Almost all respondents recommended either servicing (51.7%) or replacing (41.1%) the fire. The latter option provided higher quality, satisfaction and overall performance, but was more expensive than the other strategies. Few respondents (5.7%) recommended inspection and report by specialists, which is the most cost effective solution. Further analysis suggested that these strategies require approximately similar periods to be implemented. Servicing the fire delivered a similar level of performance as inspection and report by a specialist. In sum, the replacement of the fire provides the benchmark solution for this scenario. Table 8.22 Summary of the analysis for scenario 31: ‘A flood damaged property has a wallhung gas fire that has been in contact with floodwater’ Performance ranking Repair strategy Service the fire Replace the fire Inspection and report by specialists (qualified gas engineers) Fit the fire with new controls

Chosen by (%)

C

Q

T

S

O

51.7 41.1

2 3

3 1

2 1

3 1

3 1

5.7 1.5

1 –

2 –

3 –

2 –

2 –

Note: See Table 8.19 for explanation of symbols.

8.3.5 Scenario 32: ‘The dwelling has an electrical circuit containing sockets and cables which have been partly submerged by floodwater’ A summary of the analysis for scenario 32 is provided in Table 8.23. Most respondents (71.1%) recommended the electrical circuit be checked by an electrician and any faults rectified. This strategy performed poorly in quality and satisfaction, but was the most cost effective. Quite a considerable number (20.3%) recommended electrical wiring and fittings installed below the floodline be replaced, which provided moderate performance. Some 8.6% of respondents advocated complete replacement of this installation, which

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Table 8.23 Summary of the analysis for scenario 32: ‘The dwelling has an electrical circuit containing sockets and cables which have been partly submerged by floodwater’ Performance ranking Repair strategy An electrician to check electrical circuit and rectify any faults Replace electrical wiring and fittings installed below floodline Completely replace this installation

Chosen by (%)

C

Q

T

S

O

71.1

1

3

2

3

2

20.3

2

2

3

2

3

8.6

3

1

1

1

1

Note: See Table 8.19 for explanation of symbols.

provided higher quality, satisfaction and overall performance, but was more expensive than the other strategies. Deeper analysis revealed that the time required to implement these strategies is approximately the same. Checking the electrical circuit and rectifying any faults by a technician yielded a similar level of performance and was more economical than replacing electrical wiring and fittings installed below the floodline, and therefore may be preferred. Although complete replacement of the installation provided higher quality and satisfaction, it was chosen by just a few respondents because of the higher cost incurred. Nevertheless, the overall performance indicates that complete replacement of the installation is the benchmark solution for this scenario. Respondents who expressed their preference for alternative strategies, mostly recommended either replacement of electrical wiring and fittings installed below the floodline (54.2%) or complete replacement of this installation (43.8%). Generally, these strategies delivered higher quality and satisfaction; however, they incurred higher cost and more time, which precluded their use.

8.3.6 Scenario 33: ‘The dwelling has a wall-hung electrical heater that has been submerged by floodwater’ A summary of the analysis for scenario 33 is provided in Table 8.24. The opinion of the respondents was divided into two almost equal proportions, namely replacing the heater (51.1%) and asking an electrician to check the heater (48.9%). Replacing the heater performed better in all aspects except cost. Further analysis revealed that the time required to implement both strategies was perceived as being the same. These results suggest that replacing the heater delivered higher quality, satisfaction and overall performance, but was more expensive than asking an electrician to check the heater. In summary, the overall performance indicates that the replacement of the heater is the benchmark solution for this scenario.

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Table 8.24 Summary of the analysis for scenario 33: ‘The dwelling has a wall-hung electrical heater that has been submerged by floodwater’ Performance ranking Repair strategy

Chosen by (%)

C

Q

T

S

O

51.1 48.9

2 1

1 2

1 2

1 2

1 2

Replace the heater An electrician to check the heater Note: See Table 8.19 for explanation of symbols.

8.3.7 Scenario 34: ‘The dwelling has timber skirting boards’ Table 8.25 summarises the analysis for scenario 34. The opinions of the respondents were diverse regarding this scenario and almost equally divided between three options. The most popular strategy was allowing the skirting board to dry and then replacing damaged sections (37.9%); this was the most cost effective strategy, but it was considered to perform poorly in other respects. Replacing all skirting boards delivered superior performance in all respects except cost. The performance ranking of replacing skirting boards damaged by floodwater was intermediate between the first two strategies. Further analysis revealed that the time required to replace all skirting boards and to replace skirting boards damaged by floodwater was approximately the same. It was also found that the cost and time required to replace skirting boards damaged by floodwater and to allow the skirting boards to dry and then replace damaged sections of board, are approximately the same. Here, replacing skirting boards that are damaged by the floodwater may be preferred because of the higher quality, satisfaction and overall performance delivered. In sum, the overall performance suggests that the replacement of all skirting boards is the benchmark solution for this scenario.

Table 8.25 boards’

Summary of the analysis for scenario 34: ‘The dwelling has timber skirting Performance ranking

Repair strategy Allow skirting board to dry and replace damaged sections Replace all skirting boards Replace skirting boards that are damaged by the floodwater Leave existing skirting board in place Note: See Table 8.19 for explanation of symbols.

Chosen by (%)

C

Q

T

S

O

37.9 32.2

1 3

3 1

3 1

3 1

3 1

29.5 0.4

2 –

2 –

2 –

2 –

2 –

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8.3.8 Scenario 35: ‘The dwelling has a staircase constructed from timber’ Table 8.26 summarises the analysis for scenario 35. Almost all respondents (89.6%) recommended the stairs be allowed to dry and then any damage caused be assessed, which performed better in cost and time. Some (8.8%) advocated replacement of timber components that had been in contact with floodwater, which produced higher quality, satisfaction and overall performance. Complete replacement of the staircase and leaving the stairs alone were chosen by very few (1.2% and 0.4%, respectively), suggesting that these strategies are not feasible. Deeper analysis revealed that allowing the stairs to dry and then assessing any damage caused, and replacing timber components that had been in contact with floodwater, required the same time and produced the same overall performance. Nevertheless, replacement of timber components that have been in contact with floodwater is considered the benchmark solution for this scenario. Table 8.26 Summary of the analysis for scenario 35: ‘The dwelling has a staircase constructed from timber’ Performance ranking Repair strategy Allow the stairs to dry and then assess any damage caused Replace timber components that have been in contact with floodwater Completely replace the staircase Leave the stairs alone

Chosen by (%)

C

Q

T

S

O

89.6

1

2

1

2

2

8.8 1.2 0.4

2 – –

1 – –

2 – –

1 – –

1 – –

Note: See Table 8.19 for explanation of symbols.

8.3.9 Scenario 36: ‘The dwelling has built-in wall cupboards’ A summary of the analysis for scenario 36 is provided in Table 8.27. The majority of the respondents (65.5%) recommended the cupboards be allowed to dry and then any damage caused be assessed, which was the most cost effective strategy; 25.2% recommended complete replacement of the cupboards, which performed better in all respects except cost. Some (9.3%) recommended the replacement of timber components that had been in contact with floodwater. Further analysis discovered that the time required to implement these strategies is approximately the same. It was also found that replacing timber components, and allowing the cupboards to dry and then assessing any damage produced the same level of quality, satisfaction and overall performance, and required the same time to be implemented. Here, allowing the cupboards to dry and then assessing any damage caused may be

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Table 8.27 Summary of the analysis for scenario 36: ‘The dwelling has built-in wall cupboards’ Performance ranking Repair strategy Allow the cupboards to dry and then assess any damage caused Completely replace the cupboards Replace timber components that have been in contact with floodwater

Chosen by (%)

C

Q

T

S

O

65.5 25.2

1 3

3 1

2 1

3 1

2 1

9.3

2

2

3

2

3

Note: See Table 8.19 for explanation of symbols.

preferred, as this is more cost effective. Nonetheless, the complete replacement of the cupboards is considered the benchmark solution for this scenario. The analysis of ideal repair strategies revealed that complete replacement of the cupboards was the most popular ideal strategy. Generally, the increased cost was the principal reason for not employing this strategy.

8.3.10 Scenario 37: ‘The dwelling has a ‘‘fitted’’ kitchen that has been partially submerged above the plinths by floodwater’ A summary of the analysis for scenario 37 is presented in Table 8.28. There was disparity of opinion regarding present repair strategies. Most respondents recommended either replacing those units that had been in contact with the floodwater (43.7%) or allowing the units to dry out and replacing only those kitchen unit panels that had been damaged (39.5%); the latter was the most cost effective solution. Quite a considerable number (16.9%) advocated replacement of the complete kitchen, which delivered higher quality, satisfaction and overall performance. Deeper analysis indicated that the time required to implement these strategies is approximately the same. Allowing Table 8.28 Summary of the analysis for scenario 37: ‘The dwelling has a ‘fitted’ kitchen that has been partially submerged above the plinths by floodwater’ Performance ranking Repair strategy Replace those units that have been in contact with floodwater Allow the units to dry out and replace only those kitchen unit panels that have been damaged Completely replace the kitchen Note: See Table 8.19 for explanation of symbols.

Chosen by (%)

C

Q

T

S

O

43.7

2

2

1

2

2

39.5 16.9

1 3

3 1

3 1

3 1

2 1

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the units to dry out and then replacing only damaged kitchen unit panels, produced a similar level of performance, but was more cost effective than replacing those units that had been in contact with floodwater, and therefore may be the preferred choice. The analysis of ideal strategies revealed that the replacement of the complete kitchen was the most favoured ideal repair strategy. A comparison between present and ideal repair strategies suggested that, generally, the respondents who recommended an alternative strategy would have preferred options which delivered higher quality and satisfaction; however, these were considered prohibitively expensive. In sum, the overall performance indicates that the complete replacement of the kitchen is the benchmark solution for this scenario. The next chapter contains the conclusions of this book together with recommendations for the industry and for further research.

9 9.1

Conclusions and Summary Introduction This chapter gives the conclusions of the two-year research project into the development of benchmark standards for the repair and restoration of flood damaged domestic properties described in this book. Presently, much flood damage assessment relies heavily upon surveyors’ individual perceptions and attitudes towards the repair work required for any given flood damage condition. Such assessments are subjective and prone to significant variance; this can ultimately lead to conflict between interested parties (e.g. the insured and the insurer) and so hamper performance and reduce customer satisfaction. A summary of flood characteristics and their perceived importance according to the views of experts is first presented. Current methods and practices used in the process of drying out flooded properties are described. Then, a summary of the benchmark standards for the reinstatement of flooded properties including those for floors, walls, doors and windows, utilities and fittings are presented. These benchmarks represent those repair strategies which yield best performance in terms of cost, quality, time and satisfaction combined. Several tendencies found in the assessment of flood damage are also discussed. Finally, recommendations for further research and for uptake by the industry are proposed.

9.2

Flood characteristics Flood characteristics were classified as contaminant content, velocity, duration, sewage and fasciae content, source of the floodwater and floodwater depth. According to the views of experts, sewage and fasciae content of floodwater is considered the most important characteristic, followed by contaminant content, depth, duration, source and velocity of flow. All characteristics are considered ‘important’ or ‘very important’, apart from velocity of flow. The ‘content’ (both sewage and contaminant) and ‘depth’ of floodwater are ‘very important’ flood characteristics as these generally determine the level of damage and hence costs involved in repair works. Those with more experience (particularly in the number of properties surveyed over the last 2, 5 and 10 years) tend to give more weight to flood characteristics (apart from velocity of flow) than less experienced practitioners.

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Conclusions and Summary

195

With regard to the sources of information and methods used by practitioners to determine various flood characteristics, it is known that at the present time flood damage assessors rely heavily on visual inspections (i.e. independent judgements) and local information and/or witnesses, probably because information gathering can be extremely time consuming. Currently assessment of flood damaged properties is somewhat subjective and therefore prone to variation. Furthermore, in the absence of hard evidence and objective information, assessors tend to pursue other sources of information (e.g. from witnesses of the flood) which may be less reliable, particularly for determining the contaminant content, sewage and fasciae content, duration of flood and source of floodwater. In contrast, current practice relies heavily on visual inspection to determine floodwater depth. This is significant, because these flood characteristics are considered highly important in flood damage assessment.

9.3

Drying out flooded buildings Methods and/or equipment employed to dry flood damaged buildings, to seal off sections of the building to assist drying, and to determine if a building is sufficiently dry for repair works to commence are now described.

9.3.1 Methods and/or equipment employed to dry flood damaged buildings Surveyors recommended various methods to assist drying rather than focus on a single dominant method. The most popular method is to use the existing heating system, a method considered to be practical and timely. However, natural ventilation is also commonly used, despite this being the least effective drying method. Generally, with the exception of natural ventilation, all other methods are considered quite effective. Most surveyors would prefer to use different drying methods but external constraints do not allow this. The use of temporary heating is the preferred solution, but this can be costly to employ. The use of desiccant dehumidifiers is considered the most effective method of drying flooded buildings, followed by natural ventilation. Property size (in terms of volume, area, number of rooms) was thought to be the most important factor in determining the number of dehumidifiers to be installed in a flood damaged property, although many surveyors would seek advice from specialist contractors. Some damage assessors rely on experienced-based trial and error or rules of thumb (e.g. two dehumidifiers per semi-detached house). This indicates that, for some surveyors, drying out is not a scientific process but rather one based on experience and subjectivity,

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the reliability of which must be doubted. Thus, current practice regarding drying out may not always be effective and therefore scope for improvement exists.

9.3.2 Sealing off sections of the building to assist drying Most surveyors seal the property into a number of sections to assist the drying procedure, depending on the individual characteristics of the property and the flood. Some surveyors use ‘scientific’ methods such as dehumidifier capacity and the volume of each room to determine an appropriate number of sections, whilst some use more ‘practical’ methods including the sealing of each room. Again, this suggests a high degree of subjectivity on the part of flood damage assessors. Electric warm air heaters are most usually used to assist drying; these offer advantages over gas-fired heaters because they do not create additional moisture when used.

9.3.3 Methods and/or equipment employed to determine if a building is sufficiently dry for repair works to commence There is generally a lack of knowledge regarding appropriate methods for determining dampness levels, with rather subjective methods (e.g. based on visual observation or allowing a set number of days to pass after the flood) being the most common. These methods are considered to be the least effective, but ironically are used quite extensively. Electrical resistance meters are also quite commonly employed; however, these are known to be rather unreliable because of their sensitivity to the salt which is commonly found in masonry. Calcium carbide moisture meters are the most effective, although these are not commonly used by surveyors.

9.4

Reinstatement of flood damaged domestic properties The benchmarks for flood damaged floors, walls, doors and windows, and utilities and fittings scenarios are summarised in Tables 9.1–9.4.

9.4.1 Tendencies in the reinstatement of flood damaged properties The research revealed several tendencies in the reinstatement of flood damaged properties, which can be summarised as follows: .

The most popular strategy is not necessarily the best solution in terms of cost, quality, time and satisfaction, nor was it the ‘benchmark’ for a particular flood condition.

Conclusions and Summary

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Table 9.1 Flood damage scenarios and their benchmark repair strategies for the reinstatement of flood damaged floors Flood damage scenario

Benchmark repair strategy

(1) ‘The dwelling has vinyl floor tiles installed that have been submerged by floodwater’ (2) ‘The dwelling has a vinyl sheet floor covering installed that has been submerged by floodwater’ (3) ‘The dwelling has a quarry tiled floor which has been submerged by floodwater’ (4) ‘The dwelling has a solid concrete floor which has been submerged by floodwater’ (5) ‘The dwelling has a suspended timber (chipboard) floor which has been submerged by floodwater’ (6) ‘The dwelling has a suspended timber (chipboard) floor with tongue and grooved floorboards’ (7) ‘When the floorboards are removed, it is discovered that the sleeper walls are constructed directly on the ground (i.e. no concrete slab has been included)’ (8) ‘The dwelling has a concrete floor which has been covered with solid oak blocks’

Replacement of all floor tiles

Replacement of the floor covering

The floor tiles are cleaned in place

The floor is cleaned and allowed to dry

Replacement of chipboard and only warped and rotten timber components Removal and replacement of all timber components (joists, floorboards, skirting, etc.) A dpc is installed into the present sleeper walls

Replace all floor covering (i.e. the oak blocks)

Table 9.2 Flood damage scenarios and their benchmark repair strategies for the reinstatement of flood damaged walls Flood damage scenario

Benchmark repair strategy

(9) ‘The external wall of the property is brickwork with cement mortar joints’ (10) ‘The external wall of the property has a rendered finish’ (11) ‘The external wall of the property has a pebbledash finish’ (12) ‘An internal wall of the flood damaged property is constructed of brickwork with a paint finish applied directly to it’ (13) ‘An internal wall of the flood damaged property has been covered with ceramic tiles’ (14) ‘An internal wall of the flood damaged property has been covered with a wood veneer on timber grounds’

Clean the wall Clean the render Clean the pebbledash render Clean and repaint the wall

Replace all tiles

Replace the wood veneer

Continued

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Table 9.2

Continued

Flood damage scenario

Benchmark repair strategy

(15) ‘An internal wall of the flood damaged property has been decorated with wallpaper’ (16) ‘An external wall of a flood damaged property has evidence of a rising damp problem’ (17) ‘Following removal of the wall’s plaster, it is found that the wall has been incorrectly constructed’ (18) ‘Floodwater has been in contact with an internal block wall which has a gypsum plaster finish’ (19) ‘Floodwater has been in contact with an internal block wall which has a cement/ sand mix undercoat and a 1 mm plaster skim applied to it’ (20) ‘Floodwater has been in contact with an internal brick wall which is finished with a lime/ox-hair mix and a lime putty finish’ (21) ‘Floodwater has been in contact with an internal timber partition wall’ (22) ‘Floodwater has been in contact with an internal metal-framed partition wall’

Replace all wallpaper

Inject the wall with a dpc and replace the plaster Plaster the wall

Replace all the wall’s plaster

Clean the plaster

Replace all the wall’s plaster

Replace all plasterboard Replace metal components and plasterboard

Table 9.3 Flood damage scenarios and their benchmark repair strategies for the reinstatement of flood damaged doors and windows Flood damage scenario

Benchmark repair strategy

(23) ‘A flood damaged property has a softwood wooden front door that has been in contact with floodwater’ (24) ‘A flood damaged property has double glazed hardwood patio doors that have been in contact with floodwater’ (25) ‘A flood damaged property has hollow cellular type infill wooden doors that have been in contact with floodwater’ (26) ‘A flood damaged property has a PVC external door that has been in contact with floodwater’ (27) ‘A flood damaged property has wooden window frames that have been in contact with floodwater’

Replace the door

Allow the door to dry out and then assess the damage, before replacement of the glazing units if the seals have perished Replace the door

Clean the door only

Allow the windows to dry out and then assess the damage, before replacement of the glazing units if the seals have perished

Conclusions and Summary

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Table 9.4 Flood damage scenarios and their benchmark repair strategies for the reinstatement of flood damaged utilities Flood damage scenario

Benchmark repair strategy

(28) ‘A flood damaged property has steel panel radiators installed that have been in contact with floodwater’ (29) ‘A flood damaged property has a gas fired heater that has been in contact with floodwater’ (30) ‘A flood damaged property has a gas meter that has been in contact with floodwater’ (31) ‘A flood damaged property has a wallhung gas fire that has been in contact with floodwater’ (32) ‘The dwelling has an electrical circuit containing sockets and cables which have been partly submerged by floodwater’ (33) ‘The dwelling has a wall-hung electrical heater that has been submerged by floodwater’ (34) ‘The dwelling has timber skirting boards’ (35) ‘The dwelling has a staircase constructed from timber’ (36) ‘The dwelling has built-in wall cupboards’ (37) ‘The dwelling has a ‘fitted’ kitchen that has been partially submerged above the plinths by floodwater’

Allow the radiator to dry, clean/sanitise and then repaint

.

.

.

Replace the heater

Refer to gas supplier

Replace the fire

Completely replace this installation

Replace the heater

Replace all skirting boards Replace timber components that have been in contact with floodwater Completely replace the cupboards Completely replace the kitchen

Current practice demonstrates a high level of disparity with regard to repair strategies. Here, cost may not be the most important consideration in the repair of flood damaged homes. Mutual exclusivity was found to exist between the performance of the strategies. The tendency is that any strategy which delivers higher quality and/or satisfaction is more costly (i.e. shows poorer cost performance) and vice versa. Therefore, there are few strategies which perform better in all respects. Some surveyors are constrained by external factors (e.g. their employers) as to which repair strategies are employed. Many would prefer to employ strategies which deliver better quality and higher satisfaction; however, these strategies are precluded in their current employment because of the increased cost involved.

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.

.

The reinstatement of flood damaged doors and windows highlights the importance of a thorough examination before the selection of an appropriate repair strategy. For some surveyors, cost is the main consideration when choosing a repair strategy. For the reinstatement of flood damaged utilities and fittings, the time required to implement different repair strategies is not significantly different. Other performance criteria (such as cost and quality) should therefore be prioritised when choosing an appropriate solution.

9.4.2 Practical utilisation of the benchmarks The benchmarks provide professionals involved in the reinstatement of flood damaged domestic properties with guidance regarding the optimum repair strategy for typical flood damaged building elements. The benchmarks assume that equal importance is given to the performance criteria of cost, time, quality and customer satisfaction. Of course, this may not be appropriate for all situations, given the demands of modern business. The details provided for each flood situation will allow professionals to identify the most appropriate strategy for any given performance criterion. To demonstrate the practical utilisation of these benchmarks, a typical example now follows. A flood damaged property has steel panel radiators that have been in contact with floodwater, as presented in Figure 9.1. A damage assessor is faced with four possible repair strategies, as follows:

Figure 9.1

Image of flood damage scenario 28

Conclusions and Summary

Option 1: Option 2: Option 3: Option 4:

201

Recommend the radiator and valves be replaced. Recommend the radiator valves be replaced. Recommend the radiator be left alone. Allow the radiator to dry, clean/sanitise and then repaint it.

Without the benchmarks, the assessor would have to rely on past experience, which may not provide a reliable source, to determine the most appropriate repair strategy. The benchmarking exercise allows the performance of these repair strategies to be compared as presented in Figure 9.2. Let us assume that in this particular situation, time is not as important as cost; however, reasonable quality and good client satisfaction are required. In order to select the most appropriate strategies, their performance has to be evaluated. Option 3 (i.e. do nothing) is the most economical and least time consuming strategy; however, it delivers the lowest quality and satisfaction. Replacing the radiator and the valves (option 1) is the most expensive strategy, but yields the highest quality and satisfaction. The high cost involved may preclude this approach. Replacing the radiator valves (option 2) is reasonably costly, but quality, time performance and satisfaction are rather low. Allowing the radiator to dry, then cleaning/sanitising and repainting it (option 4) provides a reasonable solution with high quality and satisfaction at a fair cost. Based on this evaluation, the assessor would be able to select option 4 with confidence.

Figure 9.2 Performance comparison between repair strategies of flood damage scenario 28

9.5

Recommendations Recommendations arising from this study include those for future research and those for consideration by the industry.

202

Chapter 9

9.5.1 Recommendations for future research The scope for future research is extremely broad, given the increased likelihood of flood events. However, several specific areas have been identified and are summarised as follows. Physical experiments on the effects of flooding on domestic properties Detailed investigations on areas which exhibit high levels of subjectivity, e.g. methods of determining whether a building is sufficiently dry for repair works to commence, should be useful to the industry and very timely considering the predicted increase in flood events. The large scale physical modelling of a property subjected to artificial floods would provide invaluable information under controlled conditions. Here, the effects of various drying methods, property characteristics and flood characteristics could be evaluated in a controlled environment, allowing reliable information on optimum drying methods to be developed. In addition to this, the effects of various construction fabrics, wind speeds and ambient temperatures could also be examined. Concurrently, an independent laboratory-based evaluation of methods of determining whether a building is sufficiently dry, could be conducted. Examining the weighting of the criteria Findings of this research suggest that few strategies are superior in all aspects of performance. This may trigger a conflict of interest between parties involved in reinstating flood damaged properties. For instance, homeowners may prefer the solutions which deliver higher quality and satisfaction; however, these solutions are most likely to be more expensive than alternative strategies. In contrast, damage assessors may prefer to adopt solutions which allow homeowners to return to their property as quickly as possible, thereby minimising the cost of temporary accommodation. The benchmarks produced by this research propose optimum solutions based on equal weighting of cost, quality, time and satisfaction criteria. However, there may be cases where these criteria do not carry an equal weight. For instance, some would emphasise the importance of client satisfaction rather than time, while others may consider cost to be the most important criterion. Therefore, a systematic method to examine the impact of weight changes on the optimum solution proposed would prove very useful and valuable. This would allow optimum solutions for a range of stakeholders to be developed including, for example, clients, insurance companies, specialist contractors and loss adjusters. Ultimately, further development of this method could be embedded into a software tool aimed at advising the best solution for a particular damage scenario given the preferences of the individual organisation(s) involved.

Conclusions and Summary

203

9.5.2 Recommendations for the industry This research has confirmed that several aspects of flood damage assessment rely heavily on experiential trial and error, and independent judgements, which exhibit a high degree of subjectivity and are prone to variation. These aspects include, for example, methods of determining flood characteristics, methods of determining the number of dehumidifiers required, and methods of determining whether a building is sufficiently dry for repair works to commence. With regard to the reinstatement of flood damaged properties, current practice appears to be less effective than it could be. In most cases, current practice was found to be different to the ‘benchmark’ approach. However, most surveyors are satisfied that their current practice is reasonably effective and appropriate. There is little consensus among surveyors regarding what represents the most appropriate repair strategy. This book provides the first definitive guidance and should contribute towards the development of standards for the industry. It is recommended that guidance and training be provided to loss adjusters, building surveyors and other practitioners involved in the repair of flood damaged properties. This would help to highlight the need for more standardised assessment, which could be complemented by dissemination in appropriate trade and professional publications. This should help to standardise flood damage repair work and so alleviate many of the problems caused by the disparity presently found to exist amongst damage specialists and professionals.

Appendix A: Data Collection and Characteristics of the Survey Respondents A.1

Introduction This appendix describes the data collection process, including a detailed description of the questionnaire survey and the characteristics of those surveyors who participated in this research.

A.2

Questionnaire design and pilot survey The questionnaire was developed largely based on the findings of an earlier detailed literature review and on frequent discussions with experts. Additionally, feedback from chartered surveyors was also sought throughout the course of the project. Following a lengthy process of debate and discussion, the final version of the questionnaire was established. The questionnaire was designed around four parts. Part A concerned the characteristics of the surveyor (i.e. respondent), Part B concerned flood characteristics, Part C focused on the drying out of flooded properties and Part D (the main body of the questionnaire) presented the numerous flood damage scenarios. Here, current methods used to reinstate such damage were requested, and respondents were asked to indicate the performance of such methods against a range of criteria. The use of digital images (kindly provided by Rameses Associates) of real life flood events served to present respondents with a visual image of the condition. Additionally, a brief description of each flood scenario was also provided. Following completion of the questionnaire, a pilot survey was conducted to ensure that the questionnaire encompassed the spectrum of factors that need to be considered when evaluating a flood damaged property. The pilot survey involved a small number of surveyors from flood damage repair companies; the results confirmed that the questionnaire was correctly worded and potential response categories correctly stratified.

204

Data Collection and Characteristics of the Survey Respondents

A.3

205

Questionnaire survey The first stage of the survey involved putting an electronic version of the questionnaire onto the world-wide web. The website was then promoted to suitable practitioners via a range of initiatives, including several professional magazine publications, seminars and conferences. Generally, the response to this electronic web-based survey was disappointing. The second stage of the survey involved the distribution of 1800 questionnaires to chartered surveyors. These were selected from an RICS database of 10 000 chartered surveyors focusing mainly on members of the Residential Faculty. Surveyors located in areas affected by the autumn 2000 flooding were targeted. As the full version of the questionnaire in its hard copy format exceeds 20 pages in length, the questionnaire was divided into three parts (approximately 9–11 pages in length). Those who responded to the first part of the questionnaire were then sent the other two parts. Sixty-six responses were obtained for part 1 with a further 46 responses for parts 2 and 3, representing a response rate of 3.7% which is below that expected. Possible reasons for the poor response include the highly specialist nature of the research and the sheer volume of information requested which may have deterred respondents. It was evident from the survey that many surveyors simply did not have any experience in reinstating flooded properties and therefore were unable to respond. In view of the poor response, alternative strategies for the survey were implemented. The first of these involved the inclusion of a leaflet in the January 2002 publication of the Loss Adjuster magazine. This publication is distributed to over 5000 members of the Chartered Institute of Loss Adjusters, and was considered a novel method to target experienced practitioners; 206 completed questionnaires were obtained from this exercise. A number of completed questionnaires were also obtained from various sources, such as personal contacts, research seminars and the web-based version of the questionnaire. Table A.1 presents the final standing in respect of completed questionnaires. This large sample was considered suitable for detailed analysis.

A.4

Surveyor characteristics This section describes the characteristics of the respondents (i.e. surveyors) involved in the research. The methodology is first presented, followed by presentation of the findings and discussions.

206

Appendix A

Table A.1 Number of completed questionnaires Questionnaire distribution

Completed one part

Completed all parts

RICS residential faculty Leaflets Various sources

20

46 206 17

Total

20

269

A.4.1 Methodology Respondents were first invited to indicate details of their employer, working area, job title, duration in present job, and experience in assessing flood damaged properties (in terms of duration they had been assessing flood damaged properties and number of flood damaged properties surveyed over the past 2, 5 and 10 years). The vast majority of questions were formatted to provide a list of options/answers, allowing respondents to respond in a manner which allowed appropriate data analysis and faster completion of the questionnaire. Levels of experience in terms of the length of time involved in the assessment of flood damaged properties and number of properties previously surveyed were best collected in the form of ranges because this form allows easier recall. Each range was then assigned a numerical value allowing data analysis.

A.4.2 Results and discussion Figure A.1 presents the nature of respondents’ organisations. Most of the respondents (59.7%) were working for loss adjuster firms which is not really surprising, given that loss adjusters are the persons very much involved in the assessment of properties immediately after a flood event; 23.3% were working for surveying consultancy practices; 8% classified their organisations as consulting engineers; 6% were working for damage repair specialists. The remaining 8.6% classified their organisations as estate agents/housing associations (3.1%), environmental services (1.7%), local authorities (1.7%), insurance companies (1.4%) and architectural practices (0.7%). The total was not 100% because respondents were allowed to categorise their organisations into more than one category where appropriate. Although the majority were loss adjusters, as a whole, the views of the respondents could be deemed to represent various organisations involved in the assessment of flood damaged properties.

Data Collection and Characteristics of the Survey Respondents

Estate agent/Housing association

207

3.1 7.6

Consulting engineers

59.7

Loss adjuster 1.7

Environmental Services

6.3

Damage repair specialist

23.3

Surveying consultancy practice 0.7

Architectural practice Local authority

1.7

Insurance company

1.4 0

10

20

30

40

50

60

70

Percentage of respondents

Figure A.1 Respondent organisations

Figure A.2 exhibits the operating regions of the respondents’ organisations. Almost half of the respondents (48.9%) were working in the south-east region of the UK; 18.0% were working in the south-west. As a whole, the sample was dominated by respondents working throughout England and Wales, while few were operating in Scotland. Figure A.3 depicts the present job titles of the respondents. As previously noted, more than half were loss adjusters (31.1%) and building surveyors (21.8%) considered to have current hands-on experience in assessing flood damaged properties. More than one-third were at managerial levels, representing directors/principals (18.0%), partners (9.0%) and managers (9.0%). North-west

9.5

East Midlands

9.9

South-east

48.9 12.7

Yorkshire and Humberside Scotland

3.9 9.9

East Anglia

12.0

West Midlands

18.0

South-west Wales

8.8

The North

7.4 0

10

20

30

40

50

Percentage of respondents

Figure A.2 Operating regions in the UK of the respondents’ organisations

60

208

Appendix A

Customer service

0.3

Engineer

2.1

Technician

3.5

Claim adviser

5.2

Partner

9.0

Director / prinincipal

18.0

Manager

9.0

Surveyor

21.8

Loss adjuster

31.1 0

5

10

15

20

25

30

35

Percentage of respondents

Figure A.3 Job title of respondents

About 11% were claims advisers (5.2%), technicians (3.5%), engineers (2.1%) and customer service advisers (0.3%). In sum, respondents represent a variety of individuals involved in the assessment of flood damaged properties. Figure A.4 presents respondents’ duration in their current employment; this ranged between 1 year and more than 42 years. A majority had been employed for between 5 and 30 years, indicating extensive experience. Figure A.5 shows the respondents’ experience in terms of the number of years in assessing flood damaged properties; most (74.0%) had been assessing

Figure A.4 Respondents’ duration in current employment

Data Collection and Characteristics of the Survey Respondents

209

Figure A.5 Respondents’ experience in terms of number of years in assessing flood damaged properties

flood damaged properties for more than 5 years. The mean was 3.12 and the median was 3.00 (i.e. ranging from 10 to 15 years). These results indicate that respondents have extensive experience in the assessment of flood damaged properties and their views can be deemed to be those of experts in this domain. Figure A.6 depicts the respondents’ levels of experience in terms of the number of flood damaged properties surveyed over the past 2, 5 and 10 years; Table A.2 shows the mean, median and mode. An increase in the number of properties surveyed over the three time-spans was expected; however, the results indicate an acceleration in the number of properties surveyed by respondents over the past two years. The results suggest that respondents were generally practised flood damage assessors with various levels of experience. It is worth noting that some respondents (13.9%) had surveyed more than 226 flood damaged properties in the past 10 years, indicating very extensive experience. One respondent had no experience in flood damage assessment (Figure A.6, number of properties surveyed over the past 10 years).

210

Appendix A

Figure A.6 Respondents’ experience in terms of number of flood damaged properties surveyed over the past 2, 5 and 10 years

Data Collection and Characteristics of the Survey Respondents

Table A.2 Mean, median and mode of respondents’ experience in terms of number of flood damaged properties surveyed over the past 2, 5 and 10 years Duration Over the past 2 years Over the past 5 years Over the past 10 years

Mean

Median

Mode

3.95 5.33 6.44

3.00 5.00 5.00

3 5 5

Note: The numbers mean the following: 1, one property surveyed; 2, 2–4 properties surveyed; 3, 5–10 properties surveyed; 4, 11–25 properties surveyed; 5, 26–50 properties surveyed; 6, 51–75 properties surveyed; 7, 76–100 properties surveyed.

211

Appendix B: Useful Sources of Information Association of British Insurers www.abi.org.uk British Damage Management Association (BDMA) http://www.bdma.org.uk/info.htm Chartered Institute of Loss Adjusters (CILA) http://www.cila.co.uk/2 Construction Industry Research and Information Association (CIRIA) www.ciria.org.uk/ Department for Environment Food and Rural Affairs http://www.defra.gov.uk/ Environment Agency (England and Wales) www.environment-agency.gov.uk Flood Protection Association www.floodprotectionassociation.org Office of the Deputy Prime Minister www.safety.odpm.gov.uk/bregs/floods National Flood Forum http://www.floodforum.org.uk Northern Ireland Environment Agency www.doeni.gov.uk Scottish Environment Agency www.sepa.org.uk

212

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Index abrasion (or scouring), 18 age (of property), 6 air bricks, 14 Association of British Insurers (ABI), 2, 4, 5, 14 Authority(ies) borough authorities, 3 county authorities, 3 district authorities, 3 drainage authority, 3 highways authority, 3 local authority(ies), 2, 9, 10, 13, 23–5, 206 operating authorities, 2 unitary authorities, 3 water authority, 23–5 autoclaved aerated concrete block, 16–17 belongings personal belongings, 18 damaged belongings, 4, 18 best practice standards, 7 block wall, 105, 109, 127–9, 198 blockwork, 29, 106, 109, 111, 128, 130 brick wall, 111, 129, 198 brickwork, 29 brickwork with cement mortar joints, 78, 121, 197 brickwork with paint finish, 89, 124, 197 British Standards Institute (BSI), 14 building characteristics, 16 Building Research Association of New Zealand, 17 Building Research Establishment (BRE), 6, 17 building surveyor(s), 5, 6, 7, 203

bulletin (issued by Environment Agency), 23–4 business properties, 1 calcium carbide moisture meter(s), 36–9, 196 capillary absorption, 16 ceramic tiles, 91, 124, 197 characteristics of the property, 6 clay brick(s), 16, 28 climate changes, 1 coastal (or sea) defence(s), 2, 12 comfort and health, 34–5 composite material, 29 concrete floor, 65, 77, 197 solid concrete floor(s), 14, 52, 72–3, 197 confidence level(s) (or level of confidence), 22, 42, 47, 80, 143, 154 conflict(s), 6, 7, 194 construction form(s) (or forms of construction), 6, 12 Construction Industry Research and Information Association (CIRIA), 6, 14 construction materials, 4, 6, 16 contaminant(s), 4, 18, 19 contaminant content, 6, 8, 16, 17, 19, 20, 21, 22, 23, 25–6, 194–5 convective–diffusive transfer of vapour, 27 Corgi engineers, 157 correlation matrix, 22 corrosion, 19 councils parish councils, 3, 9, 10 town councils, 3, 10

221

222

Index

cupboards, 178–9, 191–2, 199 built-in wall cupboards, 178, 191–2, 199 customer satisfaction, 7, 8, 40, 200 dam(s), 5, 17 damage damage management companies, 6 damage management experts, 41 direct damage, 3 indirect damage, 3 physical damage, 3, 4, 17 potential damage, 5 psychological damage, 3, 4 structural damage, 4, 18 damp problem, 99, 126, 198 dehumidifier(s), 30, 31, 33, 34, 35, 39, 196, 203 desiccant dehumidifier(s), 31, 32, 33, 195 refrigerant dehumidifier(s), 31, 32, 33 Department of Environment, Food and Rural Affairs (DEFRA), 2, 13 Department for Transport, Local Government and the Regions (DTLR), 6, 11, 12, 18 digital photos/image(s), 8, 40–41, 78, 132, 152, 204 door(s) double glazed hardwood patio doors, 135, 148, 198 hollow cellular type infill wooden doors, 138, 149, 198 PVC external door, 141, 149–50, 198 softwood front door, 132, 147, 198 drainage body(ies), 3 drainage systems, 1, 3, 13, 14 drainage systems and sewers, 12, 14 drying characteristics, 16 drying methods (or method of drying), 6, 30 ideal drying methods, 32, 33 present drying methods, 30, 33 drying time, 19

electrical capacitance meter(s), 36–8 electrical circuit (containing sockets and cables), 165–6, 188–9, 199 electrical earth leakage techniques, 36–7 electrical resistance meter(s), 36–8, 196 electrical sockets, 14 embryonic forms, 19 engineering solutions, 1 Environment Agency, 2, 3, 5, 9, 10, 11, 13, 14, 15, 23–5 ephemeral watercourses, 2 fans, 30, 31, 32, 35 Federal Emergency Management Agency (FEMA), 17 finish cement/sand render finish, 111 gypsum plaster finish, 105, 127–8 lime/ox-hair mix finish, 111, 129 lime putty finish, 111, 129 paint finish, 89, 124 pebbledash finish/render, 85, 123, 197 rendered finish, 81, 122, 197 skim finish, 111 fire, 163, 188, 199 wall-hung gas fire, 162, 188, 199 flood awareness campaigns, 11 flood characteristics (or characteristics of the flood), 4, 6, 8, 15, 16, 17, 19, 20, 22, 194–5, 202, 203, 204 flood damage assessors, 19, 20, 25, 26, 34–5, 40, 42, 47, 195–6, 209 flood defence(s), 2, 3, 5, 10, 11, 12 flood defence measures, 9, 11, 17 permanent flood defences, 13 flood depth (or floodwater depth), 4, 6, 8, 9, 14, 16, 17, 18, 21, 22, 24, 194–5 flood duration (or duration of the flood), 4, 8, 9, 11, 14, 16, 17, 19, 20, 21, 22, 23, 25–6, 194–5 flood forecasting, 2 flood levels, 12 flood plain(s), 1, 5, 9, 11 flood plain maps, 9

Index

223

flood plan(s), 11 flood proofing measures, 14 flood protection measures, 9 flood protection products, 14 flood protection schemes, 10 flood resilient repairs, 14 flood resistance, 12 flood resistant construction techniques, 11 flood risk(s), 1, 5, 9, 11 flood risk assessment, 11 flood risk assessment process, 5 flood skirts, 17 flood source (or source of the floodwater), 2, 5, 6, 8, 16, 18, 20, 21, 22, 24–6, 194–5 flood wardens, 10 flood warning(s), 2, 5, 10, 11 flooding coastal flooding, 1, 9, 10 flash flooding, 9, 10, 13 groundwater flooding, 10, 12 river flooding, 2, 10 saltwater flooding, 19 sewer discharge flooding, 10 floodwater line, 111 floodwater velocity (or velocity of floodwater/flow), 8, 16, 17, 18, 20, 21, 22, 23, 25–6, 194 flow flood flow, 11 overland flow(s), 12, 13 river flow, 9 flow capacity of the river, 12 fungal attack, 39

health (of occupiers), 4, 19 heater(s), 30, 35, 156–7, 170, 187, 189–90, 199 electric bar heaters, 35 electric radiant heaters, 35 electric warm air heaters, 35, 196 gas fire(d) heaters, 35, 156, 186–7, 196, 199 wall-hung electrical heater, 169, 189–90, 199 heating central heating systems, 35 existing heating (system), 30, 31, 32, 33, 39, 195 heating system, 30, 33 temporary heating (systems), 31, 32, 33, 39, 195 home(s), 1, 2, 11 homeowner(s), 6, 202 household insurance policy, 5 householders, 10 H.R. Wallingford, 14 humidity sensor(s), 36–8 hydraulic pressure, 18

gas meter, 159, 187, 199 gas supplier, 187–8, 199 glazing units, 135, 136, 137, 141, 145, 148–51, 198 groundwater, 12, 14 levels, 2, 10, 12, 13

land drainage, 2, 3 latent defects, 39 liquid–vapour phase change, 27 local information/witness, 23–6, 195 local libraries, 9 loss adjuster(s), 5, 6, 7, 41, 203, 205–7

independent consultant, 23–5 in-house laboratories, 23–5 insurance companies, 5, 7, 206 insurance cover, 5 insurance premium, 5 insured, 5, 7, 194 insurer(s), 5, 6, 7, 41, 194 kitchen, 182–3, 192–3, 199 ‘fitted’ kitchen, 182, 192, 199

224

Index

losses intangible losses, 3 tangible losses, 3 loudhailer messages, 10 main river(s), 2, 13 Mann-Whitney test, 42 mean, 20, 22, 209, 211 measures of central tendency, 20 median, 20, 22, 209, 211 Met Office, 10 metallic fittings, 19 microwave moisture gauge(s), 36–8 mitigation measures, 5 mode, 20, 22, 209, 211 mortgage, 5 mould growth, 17 natural disasters, 1 natural ventilation, 29, 30, 31, 32, 33, 39, 195 nuclear magnetic resonance, 36–8 optimal solutions, 8, 40 Pearson’s correlation tests, 20 physical and geographical location, 17 physical deposits, 19 planning applications, 11 Planning Policy Guidance Note 25 (PPG 25), 11 plasterboard, 29, 114–15, 119, 198 porosity, 27 porous/permeable solids, 16, 19, 27 pre-incident/pre-flood condition of the house, 6, 7, 16, 17 Preparing for Floods, 12 property development, 1, 11, 12 property market, 5 property size, 33, 39, 195 public health department, 23–5 quarry tiled floor, 48, 72, 197 radar, 36–8 radiator, 152, 154, 168, 199, 200

steel panel radiators, 152, 186, 199, 200 rainfall, 1, 12, 13, 19 removable household products, 13, 14 repair specialist contractors, 7 riparian owners, 3 salt(s), 19, 37, 196 saltwater, 19 saturation, 19 Scottish Office Development Department, 19 scouring (or abrasion), 18 sea defences, 2, 12 seals, 141, 148–51 semi-detached house, 4, 18, 34, 39 sewage, 4, 19 sewage and fasciae content, 8, 16, 20, 21, 22, 24–6, 194–5 sewerage system, 3 silt, 19 skirting boards, 172, 190, 199 timber skirting boards, 172, 190, 199 sleeper walls, 61–3, 76, 197 sluices, 11 social services, 10 social and environmental impacts, 11 solid oak blocks, 65, 77, 197 sorptivity(ies), 27, 29 staircase (constructed from timber), 175, 191, 199 sterilisation, 19 structure of the building, 18, 19 subjectivity, 6, 25, 34, 37, 39, 195–6, 202, 203 suspended timber (chipboard) floor, 55, 73–4, 197 suspended timber (chipboard) floor with tongued and grooved floorboards, 58, 74–5, 197 temporary free-standing barriers, 13 terraced houses, 6 test (the) moisture content, 24–5 thermographic inspection(s), 36–8 timber floors, 14

Index

timber rot, 17 tsunami, 21 type of materials, 16 unsaturated flow theory, 27 vapour flow, 27 variations in repair recommendations, 7 vinyl floor tiles, 43, 70–71, 197 vinyl sheet floor, 45, 71, 197 visual inspection, 23–6, 195 visual observation, 35–9, 196 visual signs of subsidence, 23, 25 wall metal-framed partition wall, 118, 131, 198

timber partition wall, 114, 130, 198 wallpaper, 97, 125–6, 198 water companies, 3 water mains, 12, 13 watercourses, 1, 2, 3 natural watercourses, 3 ordinary watercourses, 2 critical ordinary watercourses, 2 water absorption characteristics, 18 wetting and drying curves, 27 wood veneer, 94–5, 125, 197 window(s), 145, 151 wooden window frames, 144, 150, 198 Yorkshire Dales, 1

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