Brick Watching

Brick Watching

Edmund W. Jupp intellect

Brick Watching

Edmund W. Jupp

intellectTM Bristol, UK Portland OR, USA

First Published in Paperback in UK in 2002 by Intellect Books, PO Box 862, Bristol BS99 1DE, UK First Published in USA in 2000 by Intellect Books, ISBS, 5804 N.E. Hassalo St, Portland, Oregon 97213-3644, USA Copyright © 2000 Intellect Ltd 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, without written permission.

Consulting Editor: Masoud Yazdani Production and Cover Design: Vishal Panjwani Production Assistant Peter Singh

A catalogue record for this book is available from the British Library ISBN 1-84150-806-3

Printed and bound in Great Britain by Cromwell Press, Wiltshire

Contents Preface

iv

Some Basics

1

Materials

9

Manufacture

22

Bricklaying

33

Examples

42

Glossary

53

Some Common Bonds

58

Different kinds of pointing

62

Further Reading

67

iii

Preface This Watching book is another in the "Watching" series. It is in the same mould as Bridge-watching, Water-watching, and Tunnel-watching, It follows the same general treatment, aiming to help to convert "looking" at things into "seeing" them. Like the others in the series it assumes no previous knowledge, and avoids as far as possible technicalities that are the proper province of the professional. Here and there we might even take a few liberties with some aspects of technical precision, in the interests of readability for those of a less mechanical turn of mind. The aim of this treatment is not to turn you into an instant expert on bricks, perhaps not even a good amateur. The hope is that it may reveal to you something of what lies behind what you see, It may lead you to pursue the subject in your own way, just as far as you like, for your own enjoyment. Brick-watching is an inexpensive pastime, which can turn an old brick wall into an exciting find, and bring to your attention the fascination that is hidden from those who look but don't see, or perhaps see but don't look. It is taken for granted that everyone knows that a brick is a lump of clay moulded into a rectangular block and then baked; but there is of course much more to it than that. For example, a casual glance at a brick wall will tell you that the bricks are a sort of red. A second look though, with a little more attention, will reveal many different hues. The bricks themselves are not identical in colour, for one thing. You may then see some of the tints of the minute plant life - blues, greens, yellows, greys, black and white. Lichens may show themselves in their delicate greys and greens. Some flowers may have snatched a foothold here and there. Those in the know will recognise the type of brick and the bond or arrangement of the courses, perhaps even making a good guess at the date of construction and the source of the bricks. You will see that the surfaces of some bricks vary from wall to wall, some smooth, some patterned.. There is plenty of brickwork around us, some of it very old, and modern applications have introduced some wonderful variety. Brickwork is to be found below ground level as well as on and above the surface. We can discover bricks in tunnels, sewers, and wells; and there are some loose ones scattered around here and there.

iv

Brick Watching

They are used to provide firm standing, too, in paving, and walkways. Some attractive patterns are to be seen in paved areas, for they can be decorative as well as practical. Besides their use for enclosures, beautiful brickwork ornamentation is to be found in gardens, large ones and small plots as well. Many an amateur bricklayer has found an enthusiasm for building walls, pergolas, and other ornamental features to add interest to the plot. Some famous people have found relaxation with a trowel and a load of some bricks in some corners of their gardens. Bricks have a splendid pedigree, going back some four thousand years, and can hold their own not only as a construction material but as an art form, too. They compete with timber, stone, concrete, steel, aluminium, and other building materials, and sometimes combine with them for special effect. They remind us of the history of a region, they show the changing fashions, and the availability of natural resources. Some brick-watchers like to take painting materials or cameras and notebooks with them on their wanderings. Others just enjoy finding and identifying interesting examples of brickwork. To some extent the weather plays no part in the pastime, though the appearance of brick structures changes with variations in sunshine or rain. Armed with a little knowledge, every brick structure is an item of interest, something to be noticed, perhaps to be jotted down in a record, or photographed, drawn, painted, remembered.

v

Brick Watching

There is so much variety in the walls, buildings, tunnels, bridges and so on made from bricks that the brick-watcher need never be at a loss. Even an isolated brick may be a cause for speculation, as to where it started, and how it came to be there, whether it is a standard or a special. Again, a ruined wall or building may reveal nothing to a casual passer-by; but to a keen and instructed eye it may tell something about events that occurred a long time ago. The walls of some old roofless barn or shed might be worth investigating. What kind of man placed the bricks in a building now forlorn? Why was it abandoned? If there are large cracks, what might have been the cause? Did a wooden lintel over an opening rot away and lead to the collapse of the overlaying courses? Did iron ties corrode and hence allow bulging of the walls? Speculation alone may not provide the answers, but could point in the right direction. Then there are all the new buildings. There is a wide choice of materials for structural undertakings. Was brick chosen for appearance, cost, or ready availability? What are the comparative costs of a wall in brick, and one in concrete, or timber? The author hopes that this gentle approach will provide some insight into the esoteric world of bricks, and will increase the pleasure of finding and studying the many brick structures (including the multitude of fascinating ruins) not only locally but all over the world. It might even convert the reader from being indifferent to becoming enthusiastic. E.W.J.

vi

Basics We start by looking at some of the basic information we need to appreciate bricks and brick structures. Firstly, as mentioned above, the brick is a block of dried clay, usually with rectangular faces and with a very long history. It generally forms part of some building, or erection, or even a path or an area of hard-standing. Bricks are arranged in as to orderly assemblies, mostly rows set one upon another, to make useful or ornamental objects and structures. Looking at the use of bricks for building, the first thing to think about when planning any brick enclosure such as a house or an office is the wall arrangement, that is the shape and amount of space to be enclosed. The designer drafts a sketch of the principal walls which define the layout. These walls are then pierced, providing openings for windows, doors and services The upper chambers and roofing will determine the scantlings or measurements of the walls to carry the loads, and the foundation work needed to support the walls bearing these loads. In earlier times the walls were natural ones, the sides of caves, cliff faces and rocks. When people needed shelter away from these natural features they used such materials as were to hand, wood, rock, clay, or plants. The realisation that clay could be used as a suitable material for building enclosures led to the making of blocks of mud or clay, and later to hardening such blocks by baking them in the sun, to produce a firmer, longer-lasting brick. Sometimes the clay was reinforced by the introduction of straw or other fibrous materials, to which reference is made in the Bible. The incorporation of straw into the clay improved it by giving it some tensile strength. Blocks thus reinforced could in effect cope with a little "pull" as well as "push". That is they could sustain some tensile as well as compressive loads, a telling advantage over plain baked mud or clay. Although generally speaking all brickwork is under compression or squeezing stress, there are cases when light tensile loading does occur. Further, when a compressive load is applied to a material it gives rise to a tensile stress at an angle to the direction of the compressive stress. So in a brick structure there is always some tension, which is minimised in the design. For example, a flat arch requires reinforcement of some kind below. Bricks reinforced with fibrous materials did not crack so readily, and after baking could be handled with fewer losses from breakages. It is the same principle that underlies the use of straw and other fibrous material in cob or mud walls.

1

Brick Watching Walls, though, are not the only structures for which bricks are suitable. Chimneys, viaducts, tunnels, pillars and arches are all well made in brick. We can use them for bridges, and towers, cisterns, waterways, and the linings or cylindrical walls in wells. They form good paving areas, and steps, too.

Used with some appreciation of their qualities they can look good, as well as being sound load-carriers and insulators. Although in themselves rigid, they offer flexibility in design and construction. Most have straight edges and flat faces, yet they are readily used for curved surfaces. In the hands of a skilled craftsman brickwork can be so placed as to delight the eye. True levels and perpendiculars, well-finished and even pointing, with perfect alignment, are signs that a good bricklayer has been at work. Bricks are surprisingly accommodating, too, for even mediocre workmanship can produce a strong wall, though the appearance might grate on an informed eye. Poor alignment and rough pointing are relatively unimportant in a garden shed perhaps, or a small barn or out-building; and within limits it is unlikely to result in premature collapse. Basically, brick making hasn't changed much over the centuries. We can look at ancient structures and recognise features seen in modern buildings. Not only the bricks themselves, but also the methods of assembling them into load-bearing edifices have survived. When we come across the work of the ancient craftsmen and look at the way they put together their buildings we can recognise the same patterns that surround us today, though the sizes, colours and shapes of the bricks may have changed.

2

Brick Watching A building brick can be of any size and shape, but it is clearly a good idea to agree on some standards, so that interchangeability is easier, and so that a designer or architect knows what to specify. First, the brick should have length, breadth and thickness differing from one another, and not be a mere cube. In this way different arrangements give the designer and bricklayer a wide choice in the ways of assembling the bricks in rows, one upon another, and side by side for strength and appearance. We shall have more to say about this later. In the past different countries have adopted slightly different dimensions, and some still do; but perhaps the largest numbers of bricks, running into many millions, even billions, conform to the old British, or Imperial dimensions English size of 9 inches by 4_ inches by 2_ inches or thereabouts, say about 215 mm by 100 mm by 65 mm. The measurements are not chosen at random. The width is about half the length, With these proportions a brick laid so as to show its smallest face offsets the next brick by a space of half a brick. In this way a course of bricks can be offset from the next course. This has an important bearing on bonding, as we shall see later. This size chosen is convenient for handling, light enough for lifting and placing with one hand, and small enough to lay in pleasing patterns. Yet it is not so small as to need large numbers to make a wall of given size. Brick-watchers sometimes carry with them a rule to measure the bricks they see. The dimensions are given in inches as well as metric equivalents, since enormous quantities of bricks were made using the Imperial system of units, and brick structures last a long time in general. Again, the sizes are approximate , because of the variation in different countries. Allowing for the mortar between the bricks, you can reckon on each one taking up a space of say about 9 x 4_" x 3". Measuring with a rule marked in inches and millimetres will reveal the standards to which the bricks were made and laid, wherever you may travel. In many places you will come across the use of squared blocks of stone used like bricks, but bonded differently. Of the large numbers of bricks made in Britain to Imperial dimensions, many found their way overseas in the thousands of ships that at one time traded between all parts of the earth. They might be used as ballast on one leg of the round trip; and when they were unloaded they could be used for building in the country of destination. This worked in both directions, and the brick-watcher can often spot by their size bricks from overseas, especially in and near seaports.

3

Brick Watching So in countries all over the world there are bricks to be measured in inches, just as there are railway lines built to the old Imperial gauge of 4ft 8_". There are some disadvantages in the metric system, and in some places where the metric system has not been imposed by edict the inch, foot, yard, and mile are still in use at the time of writing. It is of course feasible to lay bricks of different sizes in one construction, but in most cases the builders tend to use the same sizes that have been used before, even the same moulds. There was a time when, to save labour, some longer bricks were produced. They didn't last long though, so if you do see some they are rarities, and worth noting. To the casual eye a brick is just a brick; but there is a wide variety used. In Britain alone the factories produce over 250 types of brick, from which the architect can choose those best suited to the projected building. An astonishing collection of 7,000 specimens, collected from all round the world, was left to the Lancashire Museum Service by Henry Holt in 1996. That is well worth seeing. Such great variety in type provides the architect and bricklayer with a wide range by means of which attractive buildings can be planned.

A brick wall can be dreary, uninspiring, ordinary, a dull functional sort of slab hardly worth a second glance; but the potential with bricks is wonderful. To the informed brick-watcher, even a cheap little piece of wall is not without interest; but some walls and structures in brickwork are simply stunning. The choice of colour and shape in the right hands can be used to such striking effect.

4

Brick Watching Bricks of different colour, bricks with patterns or figures moulded on the face, glazed examples, all may be used to bring variety and vivacity to brickwork.

Sometimes plaster or paint is applied to brickwork, to protect or decorate it; but more and more buildings, residential as well as industrial are being designed in brick, taking advantage of the beautiful effects of bare brickwork. Many modern architects are designing lovely brick buildings, from small houses to cathedrals. In some countries wooden-framed buildings are given an outer wall of brick, real or synthetic, for the sake of appearance. From a distance it is hard to tell the difference between such imitation and the real thing. Such decorative effects are not intended to contribute towards the strength of the building. Although we shall be thinking mostly about the common house brick in what follows, other building blocks are available. For example, there are the so-called "breeze blocks", larger than the ordinary clay brick, and the cellular blocks that are filled with tiny bubbles of air, so that they are light, and form very good heat insulating walls.

5

Brick Watching Until you start thinking about it, building in brick is a simple affair. You just put down a brick, splosh some mortar on it, and put another brick on that. Then you keep on adding more dollops of mortar and more bricks till you have built whatever it is you want. It looks very easy, till you try it. If you would like to see just how wrong this is, just try it for yourself. Don't use really strong mortar, though, for it is more than likely that you will want to knock it all down again; and you might as well make that an easy job. We shall have more to say about this later. Building in brick is highly skilled work. For example, consider what is involved in putting up a short length of straightforward simple wall, one brick thick, a common enough task. Each brick has to be laid truly level length-wise as well as breadth-wise; it must lie on an even bed of mortar of the same thickness as the other courses. It has to be in a perfectly vertical position so that the succeeding courses don't cause the face of the wall to tilt. Then the space between it and the next brick must be equal to the other spaces in the wall. The perpends, or vertical lines of mortar have to be nicely lined up so that the lines do not wander as successive rows are laid. In the hands of a skilled bricklayer it looks simple, as the courses succeed one another and the structure grows with startling speed. A good craftsman can keep going at that kind of speed for hour after hour; and if he is paid by the thousand, he will use up bricks at an astonishing rate. We shall have more to say about bricklaying in a later chapter; but for the present I do hope that I have sown the seeds for a healthy respect for the bricklayer and his mate. It should be noted that a good labourer is worth his weight in gold, and can keep a couple of bricklayers busy. They often work in "gangs" and keep together for years. When you see a chance, do go and watch a bricklayer at work; but try not to interrupt him. The amount of work he does may well affect what he and his family will eat.

6

Brick Watching

You might get a chance to visit a brickyard, too. What you see will open your eyes to some hitherto unsuspected aspects of human occupation. An efficient brick-works is a smoothly flowing series of events, with materials entering, being processed, and leaving as pallets of bricks. At one time railway sidings ran into the works, but motor transport is more usual now. The lorries are equipped with hoists that move the bricks onto the lorry, and off-load them at the site, the driver usually operating the hoist with a dexterity and nicety arising from long practice. There is much less waste now than there used to be. Firing temperatures are more closely controlled, processes are checked at each stage, and handling is largely automatic. Labour costs have risen sharply since the turn of the last century, and commercial competition has compelled managers to look closely at the numbers of staff employed. So when you visit a brick works you are unlikely to see crowds of workmen about. Further, it won't be the dusty kind of place the old works were, with everything covered in a thick layer of red powder. There will be dust, and there will be noise, but not like the old days. There still exist plenty of old black and white photographs of some of the old brickyards, and it is edifying to look at them and compare the views with their modern equivalent. Some things don't change much, of course, for the end product has still to be a consignment of bricks; but there has been a great reduction in the amount of manhandling. The old photographs usually show many more men working than you would see now.

7

Brick Watching For one thing, men were needed to move the solid fuel for the kilns, as well as the raw materials and finished products. Again, horses as a source of power took up much more space than the equivalent amount in electric motors. Not only were they bulky in themselves but they took more space for manoeuvring. Their demands for fodder and water were less convenient, too, than simply throwing a switch. So the last century has seen changes mostly in handling and heating.

˚

8

Materials When we look at a brick structure we generally see two materials, the bricks themselves, and the mortar or pointing. There may be lichens, and efflorescence, and some walls are "rendered", covered in plaster coatings that conceal the bricks themselves. Sometimes, too the brickwork is covered in paint or colour-wash, or stucco; but the materials in which brick-watchers are most interested are those first two, the bricks and the the mortar between them. Lichens themselves can be a source of great interest to the brick-watcher. Their lovely colours can decorate an old wall with a rich tapestry of matt yellows, greens and greys that are a delight all the year round. This may lead the brick-watcher to leaf through a book or two on lichens and similar small plants. They form a fascinating part of the living world. Sometimes, too, little plants find their way into cracks, and flourish there, getting nutrients from the specks of soil in the pointing, blown there by the wind, washed there by the rain, or deposited by the feet of birds. Nature has at her disposal many means of propagating the species.

9

Brick Watching In the county of Devon, in southern England, there is an abundance of what is sometimes called "Devon weed", which grows on brick walls and wreaks much damage. It is sometimes called "Kiss-me-quick", too, though its true name is Red Valerian (centranthus ruber). The water within the plant, being incompressible, forces apart the bricks, breaking the pointing, and leading to the disintegration of the wall. The flowers are pink, beautiful and sweetly scented, but the damage can be devastating. There is also a white variety. During the winter they appear to die down, but when spring comes they thrust up their stems and leaves and in summer decorate the walls with bright splashes of pink. Ironically, they will cheerfully continue to grow on walls which they have themselves destroyed. It is a sturdy and persistent plant, and it is found in other parts of the world, under different names. It was introduced from the Mediterranean to Britain and elsewhere.

Brick walls are hosts to other plants, too, notably ivy (like hedera helix). This fastgrowing evergreen gets a grip on the even the smoothest of surfaces and soon covers a wall with its murderous stems, which find their way into the crevices. It can climb over stones and brick walls, with its multitude of tiny rootlets, and the roots develop into thick stems which can cause havoc as they swell in between the bricks in a wall. Ivy is not without its champions, for certain varieties are attractive to some people, and the plants are cultivated. If a wall is properly maintained though, attention must be directed to the control of such plants. There are other decorative creepers, too, that are sometimes encouraged to climb over walls, particularly those of bright hue. Sometimes you may find that in order to look at some old wall, it will be necessary to penetrate clumps of ivy, pulling back the masses of leaves. You will then find how tightly this tenacious plant clings to the bricks. 10

Brick Watching If you trace the growth down to its roots you may be surprised to find how thick and strong they are. Even when the plant is cut back severely, it puts out new growth shortly after such pruning, and within a season re-establishes itself on the area previously covered. We turn to look at the man-made aspects of brickwork, i.e. the bricks themselves and the mortar that keeps them apart. Note that although mortar consists of cement and sand, it is not there to "stick the bricks together", but to provide a cushion between them, to accommodate surface irregularities. We rarely have to look far; there is plenty of brickwork in most areas. The earliest bricks were made from mud, left to dry in the air, and later baked in the sun. They appear to have originated in the sunnier parts of the world, where supplementary heat was not required for hardening the mud blocks. They were generally cast made in wooden moulds, sometimes singly and sometimes in rows. Great precision was not sought in their manufacture, nor required. Added strength was given to these blocks by the inclusion of straw, dung, or other fibrous material. Bricks made like that were sound, and many have lasted for thousands of years. In dry regions they sit there placidly in the sun, seemingly unchanged forever. Such bricks would not last long in areas which undergo more severe weather conditions. Extremes of temperature, and intermittent water penetration between the bricks followed by freezing and thawing would rapidly destroy them. Yet, given protection, even these can be durable. In some Arab countries there are some outstandingly attractive buildings with coloured decoration, built centuries ago, whose walls have little relationship with the modern kiln-dried clay bricks of western countries today. The colours are a delight to the sensitive eye. The size of bricks has changed surprisingly little since those early days. There was more variety in size then, but usually sizes were determined by what a man's hand might span. The modern brick is standardised to practical dimensions. (There are some men with large hands who can grasp and lift two bricks at once; but they are exceptions. Try it for yourself.) Generally the sizes and weights of today's bricks have settled down to what the modern builder considers to be the convenient.

11

Brick Watching

Common bricks are made from clay, of which there is a wide variety. Looked at from one point of view it is all free, like other naturally-occurring substances, just lying there in the earth waiting to be dug up. So in one sense the clay itself doesn't cost anything. That doesn't mean you can have bricks for nothing, though. There are the wages of those who dig, and those who manage things, and the people who keep the accounts. Then there are payments to the owners of the land, and the people who carry the clay from the quarry to the brickyard. It requires cash to run lorries, to maintain machinery, and to replace tools as they wear out. There are insurance premiums to pay, work disruptions to cover, accidents to anticipate. In capitalist countries money for all this is raised by financiers. They in turn borrow it from other people and then make a charge for those who borrow it from them, to cover the expenses of administration, losses through non-payment by defaulters, the maintenance of staff and offices, and a profit margin. So although the material is basically "free", it nevertheless costs money in our society to get it out of the ground and put it in the place where we want to use it. Even in a cash-less community, where the provision of labour is the method of exchange, and there is clayey ground nearby, digging and transporting the clay cannot be done without labour. This has to come from somewhere. In Western society the exchange of labour has been made easy by the invention of the money system, but it all boils down to the same thing in the end. Money just represents labour of one kind or another. So although, like everything else in this world, materials are provided free, this is true only if you go and dig it out yourself and carry it to where it is to be used. This also depends upon the owner of the land that contains the clay. 12

Brick Watching Long ago, in primitive societies, where communal activity could and did produce dwellings, the whole community everyone weighed in, each according to his or her strength and abilities; and in the remoter parts of the globe this may still be the case. In modern civilised society, all the "free" materials are paid for by money, which is a form of exchange of labour. One man earns by his labour the means of buying the labour of someone else. We cannot make bricks with clay alone. In the process we need copious supplies of water, and clean water at that. Slime and tiny creatures have no place in a sound brick. Here again, it is "free". It just drops down from the heavens and flows along rivers or forms lakes, where man can readily recover it, taking as much as he wants. Once more though it isn't as free as that in a modern society. It costs money to build the reservoirs, and lay the pipes and install the taps, and control the whole distribution network, so that we have the desired amount of water when and where we want it. Land and water too, is owned by people or organisations; and the taking of water has to be strictly controlled. Again, it costs money to get this "free" water in civilised areas; and it has to be pumped and piped from the source. There is the provision of machinery, too, and the iron and steel, lubricants, and power, all to be organised; and these things aren't cheap. So a supply of bricks can be expensive. Yet, taken all in all, although so many people are involved, and so many processes, bricks are, surprisingly, among the cheapest of all building materials.

Houses have been built in mud, timber, steel, concrete and plastics, but bricks are still the popular choice for durability, strength, beauty and cost. 13

Brick Watching It all starts with finding a source of clay, and other minerals. Geologists study the makeup of the earth, and produce maps showing where sand, rock, shale, and so on can be found. Contractors then seek authority to go where these maps indicate that they can find the types and quantities of the various materials they want. At the local library you can see geological maps of the area, and you will find these fascinating. If you have quarries in the neighbourhood you can see why they are sited where they are. While you are poring over geological maps you may well learn a few other things about the area too, for geology is a fascinating subject. The methods used to find the extent of the various deposits of minerals and rocks below the surface are ingenious; and modern developments are intriguing.

For clay we must go to an area where the ground is clayey, and dig it out. It may not be visible on the surface, being covered with topsoil and vegetation, but we don't usually have to go down very far.. The area is carefully surveyed so that the machinery can be brought to where it can best exploit the resources, getting as much as possible of the material with the least amount of work. It may be necessary to build approach roads and offices, perhaps car parks, for most quarries are usually expected to yield for a long time before it becomes uneconomic. Since the clay is not on the surface, the quarry doesn't begin to pay till the topsoil has been removed, so this is the first job.

14

Brick Watching Before the development of steam power, and engines using petrol and oil, horses were used, dragging sturdy wooden carts. These were sometimes backed up by narrowgauge railway systems with trucks and lines in the quarry itself. These lines were often a temporary measure, so that they could be moved and adjusted as the work proceeded, and the quarry changed shape. At the end of the useful life of the quarry they might be moved elsewhere if still usable. To cope with the different levels, temporary roads may be required for the lorries to get to the various parts of the workings. These need to be substantial, even if they are temporary, for the lorries when laden are very heavy. Conveyor belt systems may be installed, in some quarries, taking the material from the working face to the loading points. Quarries are often animated dusty places of work, full of noise reverberating around the sides of the great hole in which the excavation is carried out. Eventually, when the quarry is worked out, it is abandoned. The machinery is removed and transferred to another site, and the offices are taken down. Nothing then remains but a gash in the ground. After this, Nature takes over, grass begins to carpet the bare ground, small flowers splash the area with colour, and usually the hole fills with water. Mysteriously, small fish often appear in the water, and plant life develops on the shores. Bird life plays an important part in this magical transformation. Such sites are well worth a visit. They are dangerous, because the water is usually very deep, and the sides are steep, perhaps slippery, too. You should take great care, and not go alone. Unpredictable falls may occur from the abandoned cutting faces, and the ground can be treacherous. In the old sites you may find traces indicating which material was excavated, and what means were used to dig it out and carry it away. Some local authorities lay down rules for firms to follow when abandoninga site, and turn them into sports and leisure areas. In such cases it may be difficult to find traces of the old workings. In Bedfordshire, England, old clay-pits are called "knot-holes", and they have been handled with great understanding. Water has been introduced where there was no natural water, and turned to good account for sailing and motor-boating. Some old pits are used for in-filling, tipping the rubbish of the area into the hole to get rid of it, Rotting domestic waste can produce quantities of marsh-gas or methane. This, if not tapped for heating or lighting, can be burned off with that typical soft flame of methane gas. 15

Brick Watching In countries where land is plentiful, like the Americas, or Australia, where they have not suffered from "development", there may be very large deposits of sand and clay, and quarries can run for many years, decades even. You can find some that have been operating for a very long time, and show no sign of failing. If the material sought is sand we dig down where the geologists tell us there is a worthwhile deposit of the material. We bring in digging equipment and start to dig out and carry away such amounts as are required. Like the clayquarry, careful management is needed to ensure financial viability. It is again emphasised that quarries are dangerous places for the unwary;but with permission and under supervision it can be most instructive to visit a working or abandoned quarry of any kind. It is not, very definitely not, advisable to go anywhere near quarries without permission, however safe it may seem. Modern excavation is an undertaking of remarkable ingenuity. Sometimes huge draglines or powerful water-jets are used to win the material from the site. There may be a few conveyor belts around, or barrows and trucks, to take it up to the sieves and hoppers in sand quarries just as in clay quarries. As mentioned above, managing a quarry demands skill and experience to ensure that economical use is made of the site. Decisions have to be made as to where to dig, how far down and how far along, in any particular place, and how best to position the equipment, control the output, and generally to see that all runs smoothly. Usually, lorries take away the sand, and a nice balance is needed so that when a lorry arrives it can be loaded without delay. Carts and lorries formerly carried sand loose, with tipping arrangements,and at the site they dumped it onto the ground in a heap. The angle of repose of dry sand is small, so that the cone of material necessarily covers a large area. Wet sand piles have steeper sides, but are less stable. Even when the sand was delivered dry, rain could form runnels in the heap, and make the whole thing rather messy. From there it was at one time shovelled up by hand as required, a wasteful and inefficient process. If the angle of repose for the sand is A, then the base diameter b of a cone of height h is given by 2h /b = tan A 16

Brick Watching So if we pile up the sand to a height h, it will spread out over a diameter of 2h/tan A. Nowadays, sand is usually delivered in large reinforced plastic sacks, roughly cubic in shape, with strong handles that can be hitched onto the hook of a crane. On site, they are lowered neatly onto the ground, the material being contained by the sack, and not wastefully spread over the area. The sacks are reusable, and are collected after the contents have been removed. At the quarry, destinations and availability of transport and drivers are the determining factors for planning deliveries. Staff sees that the material is distributed according to demand. Haphazard operation would be a recipe for financial ruin. A lorry standing idle, with its driver, is a costly liability. Likewise a pile of material awaiting collection is wasting money. A profitable quarry is one where material is dug out and delivered without hanging about, supply and delivery keeping pace. The old tag "Time is money" has particular force when winning sand and clay from the ground. It matters much more these days, when labour costs are so high, comparatively. Clay is dug from clay quarries of course. From different regions we get clays of different properties, and so we have bricks that differ in characteristics and appearance, quite apart from the diversity arising from variations of treatment in the kilns. A good clay might contain about two thirds silica, and a fifth alumina, the rest being other materials like iron, manganese and lime. Clays from different areas vary in content, and quarry men can be choosy..Too much alumina for example, can lead to shrinkage and cracking. There may be inclusions of stones and other material. The colour of a brick depends upon the clay, the kind of sand used for the moulds, and the treatment. A white brick is produced from pure clay, without iron, sometimes with added chalk.

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Brick Watching If iron is added, a range of colours from light yellow to orange and red can be obtained. A blue hue can be had with about a tenth content of iron and a high kiln temperature. Other material, such as chalk, may be added to the clay to alter the properties. A sandy clay produces brittle porous bricks. You are unlikely to see that kind of brick except on the reject heap in some old brickyard. This reject heap contains examples of other defects, too, broken or burned bricks, and discoloured specimens. Such material is normally sold and used as hardcore, for filling in soft patches on building sites, as foundation material for roads and pathways, and so on. Nothing seems to be wasted Nowadays, careful quality control at all stages leads to unsuitable clay being rejected before time is wasted on processing it. The clay can be left to "weather" before being moistened and worked into a suitable consistency for moulding. Old methods required much labour, for the moulds were charged by hand. Early machinery was rugged, but not always as reliable as one would wish. Hand-made bricks are uneven in shape, without the sharp arrises found on wire-cut or pressed bricks. They used to fetch a higher price. Modern brick-making machinery is rapid and dependable, producing clay blocks of uniform size and shape at high rates. Whereas the early brick-making plants employed large numbers of manual workers, the modern plant doesn't need so many foremen and labourers, but does provide work for more machine operatives, (and accountants too!) The colour of the finished brick depends chiefly upon the amount of iron present in the clay and the firing temperature. Old buildings in some parts of the country can show by the colour of the brickwork the regions from which the bricks came. Modern brickyards can modify the colour of the bricks during manufacture. The contractor can order from a catalogue according to the colour he seeks.

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Brick Watching

Architects, engineers and builders plan their work to produce pleasing effects, by attention to texture and colour, and there are some excellent samples of careful consideration of this aspect in brick buildings everywhere. Putting together bricks of various hues in patterns can produce pictorial effects to liven a large bare wall. Engineers are usually employed in the design of industrial buildings to house machinery and other plant, plain practical erections where the special qualities of the architect may count for less. Turning now to the other important material, mortar, we are here concerned principally with cement and sand. Cement is a mixture of clay and lime. The well-known Portland cement, so called from its colour resembling Portland stone, is mostly lime, with about a third clay. The lime is obtained from chalk, a material abundant in many places. Many people will be familiar with the white cliffs of Dover, on the south coast of England, for example. These are solid chalk. There are similar large deposits in other parts of the world. Their white colour renders them prominent. In the case of the Dover cliffs these shine brightly because the near-vertical cliffs face south, into the sun. Thus, on a sunny day, they can be seen from a long way away. At one time chalk was conveyed in ships, which could sail up the estuaries and await low water. Then, when the ships took the ground, men would unload the material onto the beach, or into waiting carts drawn by horses.

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Brick Watching

They would take the carts filled with chalk to the kilns, which had been built near the shore. In many places these old kilns can still be seen, though out of use now. Chalk and clay are thoroughly ground and mixed together before heating in a kiln. It may be mixed with water to form a slurry, or fed in dry. The temperature in the kiln approaches 1500°C. The clinker resulting from this heating is then ground to a fine powder by powerful machinery, the principal source of noise in the works. The characteristics of this powder are determined by the proportions of the the basic lime and clay, the firing conditions and the addition of other substances such as iron, and alumina compounds. This is the realm of the cement chemist. So the production of cement is not quite the simple process that might be imagined from the look of the finished sack of powder. Different kinds of cement behave in various ways when used, mainly in the speed of setting. For the bricklayer, using mortar made from sand and cement, speed of setting is important. If it goes off too quickly it is a hindrance to his work, hardening before he has positioned the bricks. On the other hand a very slow-setting cement can hold up his work, especially if the mortar is not stiff. He requires a mortar that will stay workable while he positions the bricks, and thereafter to harden sufficiently in time for him to lay the next course without undue delay.

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Brick Watching These then, clay and sand, are the principal materials used in the manufacture of bricks. Other substances are involved, too, but these are in small amounts. When examining a brick structure the lines of mortar can reveal much. In old brickwork the mortar may have deteriorated, allowing water to penetrate,and thus lead to failure of the wall. In a properly maintained wall, re-pointing is carried out as required. This involves digging out the old mortar to a depth sufficient to allow new mortar to be pushed in between the bricks. In this way an old wall can be given protection and a new lease of life. If a wall or any other brick structure is neglected it can be a costly business to rebuild. It is not the materials that are expensive, but the labour. So if good materials are used in the first place, and prudent maintenance is practised, the labour of a rebuild can be avoided. Both bricks and mortar are durable materials, as is readily seen all over the world where ancient buildings in brick still stand. Apart from the physical activities of earthquakes and subsidence, the principal enemies are water and ice, especially where extensive changes of temperature take place.

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Manufacture Making bricks is an ancient art, and we can't give a definite date as to when it began, though we are told they were making bricks of some kind in Palestine nearly ten thousand years ago. In the Middle East conditions were, and still are, excellent for drying blocks in the sun, and they learned to bake them in kilns. Glazed bricks, too, were produced for durable and beautiful decorative effects. Many of which are still to be seen. The basic idea was simple enough. You dug up a handful of mud or clay, and popped it into some sort of mould, perhaps a suitable little hole in the ground or a wooden box open at the top and bottom resting on a flat surface. When the clay or mud was dry and hardened you took out the solid lump and made another, and another, and another, till you had enough to build up a wall, or a tower, a ziggurat, or whatever took your fancy. We can find traces of such bricks in ancient sites all over the world, for a well-made brick is durable in favourable conditions. Sizes are different now, of course, and production methods have changed with the development of machinery. The most noticeable advances are in methods of moving the raw material and the finished bricks. Basically, though, the actual process of making a brick still consists of digging up clay and putting it into a mould. The geologist is the expert who finds the source of clay suitable for making bricks. Modern geological methods have replaced the old methods of dig-and-see-what-youfind. Once the area is defined then in come the big excavators and the digging can start. Quarries are dangerous places, but well worth a visit, under supervision. As the diggers gouge out the clay the lorries stand by to carry it off to the brickyard or to form heaps awaiting transport. Sometimes conveyor belts or other means may be used to bring the clay to suitable loading points.

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Brick Watching

Some brickyards are sited at the quarries where the clay is available, but in some cases this raw material is brought in to the brickworks by lorry. At one time busy little brick factories were scattered everywhere, but with the availability of rapid means of transport for heavy loads modern brick-making tends to be concentrated in fewer, larger sites, close to main road systems. The older brickyards are usually to be found alongside railway lines or canals, transport facilities essential for the distribution of their products. Many have been abandoned now. Modern palletting methods, trucks and cranes, and the growth of huge road haulage systems, have made the siting of depots less dependent upon the canals and railways. Making bricks can be a noisy and dusty business, so brickworks are not popular in residential areas. In some cases early brickyards have been swallowed by urban development, but new ones tend to be sited clear of the towns. With permission from the Manager, you would find a visit to your nearest brickworks a stimulating experience. It is advisable to make your visit in suitable clothing, perhaps rubber boots. It is no place for the well-turned-out type.

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Brick Watching You should perhaps be warned that in spite of the progress made over the centuries there is still plenty of dust and, if it rains, lots of red mud. However, most of the processes take place under cover. The machinery is impressive, and unavoidably noisy too. Impressive, also, are the numbers of bricks produced, and the variety. Processes have been speeded, and the machinery is versatile so that changes in output are easily arranged. There is an air of steady movement throughout the plant in brickworks, and feeling of flow as raw material enters and finished products leave.

When the clay is dug out at the quarry it is not used at once, but given time to "weather" above ground. The colour depends upon the source of the clay. It usually contains lumps of stone and so on, but these are not removed. Powerful crushers grind it all to a coarse granulated condition like dark brown moist sugar. These crushers are ruthless unstoppable monsters, great rollers running round hard tracks, grinding all into coarse granules

. This material, like the raw clay, is moved by conveyor belt to the different parts of the works, where machinery prepares it for moulding, and shapes it as required. The first process usually produces a long moist slab, which is then sliced into brick-sized lumps of the right shape. At this stage the bricks are soft and damp, the same colour as that of the clay. They are sufficiently firm to be handled, but deform easily. At this stage there is little handling by the workmen

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Brick Watching

. The shaped blocks of clay are piled onto large flat trucks, which run on rails into the furnaces. The kilns are long, and the temperature increases as the truck penetrates further and further into the inferno. Although well insulated, the heat is such that it can be felt on the walls. There are thermometers along the outside of the kilns so that the temperature at particular points can be read. As each truckload of these soft nearly-bricks enters at one end, a load of nearly-finished articles emerges from the far end, so that the whole process is continuous. Once the trucks enter the kilns they are not handled again till after they have completed their long hot journey, and arrive at the cooler air at the far end. The emerging bricks are hard, and pretty well ready to use. However, they are still hot, and some of them will have been damaged during the process of firing. So they move along to racks where they will be inspected and sorted. Finished bricks are usually graded into three kinds, (i) those that are perfect, (ii) the imperfect but usable ones ("seconds"), and (iii) the rejects. There is a demand for all three lots, and there is little real waste. Builders would not use an imperfect brick on the outer face of a wall; but seconds are sound enough for use where appearance is of no consequence, and where perhaps they will be covered by rendering or paint-work later. The seconds may have minor defects of shape or colour, imperfections not so serious as to justify complete rejection, but such that the brick is unfit for work of good quality.

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Brick Watching

The rejects are set aside for use as hardcore, material hard enough to fill in depressions, and sustain heavy loading as it is forced down into underlying softer ground. It may be used as the basis for a track or road. The rejects may have serious cracks or be distorted in some way. They may have been badly burned, or suffered other damage inside the kiln. There is a steady demand for hardcore, though, and brickyards have no difficulty in disposing of it. Builders working on "green field sites" often require hardcore, or rubble. The lorries that carry hardcore lead a tough life, for the material is highly abrasive, and loaders just pour the stuff into the back of the vehicle with much bumping and bashing, unlike the comparatively gentle loading of palleted bricks. If you look at any of the lorries carrying hardcore you will notice the battered sides and dents testifying to this rough treatment. So the lorries are built to withstand severe handling. The engines need to be powerful, with gear ratios that enable them to climb steep inclines, and to handle the great loads of dense material they carry. On the roads traffic may sometimes be compelled to crawl up narrow hills behind lorries heavily laden with hardcore.

To produce interesting patterns, or to fit the architecture, specials are often specified. These specials are bricks which do not conform to either the shape or size of the more 26

Brick Watching usual brick. Special shapes are usually made to fit in with the standard bricks as far as possible. Using only the ordinary rectangular shape it is possible to produce many beautiful and intriguing patterns, striking and ingenious displays of the bricklayer's art. So the demand for the standard brick is enormous; and the introduction of only a few different shapes extends the scope surprisingly. Perhaps the commonest departure from the rectangular block shape is the kind used for coping, or laying along the top of a wall. Coping bricks may be flat on one face and arched on the upper face, or ridged, so as to throw off rain. Other special shapes are available for forming architectural features, floral patterns, and so on.

Specials made for paving areas are thinner, and are referred to as "pavers". Making these is straightforward enough, since only one dimension has to be altered. Paving in bricks produces an attractive hard-wearing surface, popular in domestic sites as well as in factories. It is more expensive to pay, in man-hours, and must be laid on a firm foundation of sand. The most important enemy is the weed. All kinds of weeds can take root in the joints, and grass can flourish once it takes root. The tiny seeds are scattered by wind, water, and birds, the growth is vigorous, and the damage considerable. Brickyards can be helpful in producing unusual shapes, though if the order is for a small number they will of course prove expensive. Some brick-makers maintain large stocks of the commoner "specials" as can be seen at their works. Builders' merchants, though, stock more of the concrete blocks than ordinary clay bricks. Because of changing demand the stocks held at brickyards vary; but there are always plenty of specials of certain shapes and face pattern. Since so many of the old-established brickworks are placed beside railway lines, commuters who pass brickyards on their way to work can notice the ebb and flow, the changing pattern of brick-piles in the yards. There are times when a large housing 27

Brick Watching estate is being developed, with a demand for thousands of bricks of one particular type, even millions. Then it pays a brickyard to produce that type in quantity. When a brick is needed which is standard in most respects but has perhaps one face simply decorated in a certain way this can be dealt with by scratching the face while still soft. This is a surprisingly simple way of producing interesting effects in a wall. A few wavy lines on a brick face can produce an attractive pattern in a wall where such bricks are used either in a block, or spaced regularly among standard bricks.

To produce perforated bricks, that is ones with holes passing right through the largest faces, pegs are pushed through the bricks while still soft. Cornerscan be rounded, too, while in this state. The frog, or depression in one of the largest faces, is formed in the mould. Dimpled faces are easily formed by a suitably shaped mould. Any kind of pattern can be drawn on the brick in its soft state. The scope is endless. After firing and sorting into appropriate piles the bricks are moved on pallets to the yard for storage. They are usually packed together in blocks bound with with metallic or plastic straps. These blocks are convenient for lifting by fork-lift trucks onto the lorries for despatch to the site. The manufacture of bricks is separate from the manufacture of mortar, which is normally carried out on site. Mortar is a mixture of cement and sand, with added water. Sand consists of small particles of various minerals, mostly quartz. It is normally quarried, and may vary in colour from rich golden hues through reds and browns, and even white. Due to vertical movements of the earth's crust, deposits of sand may be found far from the sea. Sand consists of fine grains or particles that have resulted from successive grinding together of rocks through massive movements of the earth over the ages. One lot of sand may look pretty much like any other lot; but a peep through a powerful microscope reveals a magnificent world of miniature multi-coloured odd-shaped rocks. With even a modest magnifying glass it is easy to see what a fascinating world there is in a handful of sand. 28

Brick Watching Granular substances can be piled, and the slope of the sides of the pile depends upon the material and the moisture content. When extra material is added to a pile most of the additional grains tumble down the sides, so that the same slope is maintained. This slope is referred to as the "angle of repose". When sand is wet the angle of repose is quite different from that for dry sand. You can see this for yourself if you pour out a bucketful of dry sand, measure the angle of repose, and then repeat the process after the sand has been wetted. This is of some importance when storing sand, of course. If not restrained by bunkers, dry sand spreads over more ground than it does when damp. Builders talk of "sharp" sand, and they mean by this sand containing tiny pieces which under the microscope are seen to be not rounded but have clear edges. Microscopic views of different kinds of sand can reveal the variation in the shape, colour and size of the tiny rocks. For making mortar the builder orders the sand from a quarry or supplier, and it used to arrive in the back of a lorry, at the site, where it was unceremoniously dumped in a pile at some convenient spot. The angle of repose, the slope of the heap, depended upon the moisture content of the sand, so that it spread over the ground according to the weather conditions. This wasteful procedure is being replaced by the packaging of sand in plastic containers, as mentioned earlier. In this way it is easier to control the quantities of sand to be mixed with the cement. Also it avoids the contamination that used to arise from soil and stones at the site. Cement is the material which binds together the granules of sand into a compact mass, forming a cushion between adjacent bricks. It is prepared from lime and clay, about a third clay and two thirds lime. The materials are burnt and ground together and stored in dry conditions. If cement is not properly stored it "goes off", and will not perform as it ought. Left in a damp atmosphere a sack of cement will set into a solid lump.

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Brick Watching The cement is mixed with sand to make the mortar, which is then supplied to the bricklayer. If you examine some of the old brick structures the mortar in the joints between the bricks can sometimes be seen to have deteriorated, and show the sand and lime separated. You may even find tiny shells and other evidence of the lime having been dug out of chalk deposits. Modern walls will not yield such interesting finds though. Often the preparation of the mortar is carried out by the bricklayer's assistant, or mate; but conditions vary as between a large construction site and a small jobbing builder's workplace. A sack of cement and a few bags of sand are enough for the small job, with a board for mixing the mortar and a bucket of water to hand. The bricklayer himself might mix the mortar for very such small jobs. On a large site a mechanical mixer will usually be required, and the mortar may be made at some central point on the site and conveyed to the scene of operations as required. It is important that the supply of mortar keep up with the demands of the bricklayer, for his time is expensive. Bricks and mortar have to be at hand as he uses them. Old wells tended to be built in lime mortar rather than the harder cement mortar. A compromise with part lime and part cement produces a softer mix. Lining the early wells in brick was an undertaking demanding great skill. Here and there, in the lower courses, bricks were omitted to permit percolation of the water into the well from the surrounding aquifer. Wells were dangerous places when children were about, for there was rarely any grid to prevent a child from falling right down to the water. In many places a windlass was built over the well. A chain was wound round the barrel of the windlass, to which a bucket was attached. Well water was mostly sweet and pure, and much preferred to mains water by some people. Mixing mortar is not quite as simple as it might appear at first glance. Like the mixing of concrete, cleanliness is of prime importance. Inclusions of foreign matter produce weak mortar, unable to do its job properly in the structure. Good sharp sand, good quality cement, and clean water together make good mortar. The task demanded of mortar is that it shall be sufficiently fluid to settle into the minor holes in the surface of the brick, yet not so sloppy as to be unable to sustain the weight of a brick when wet. Further, it must have enough compressive strength when set. Examination of poor brickwork might show uneven pointing and badly aligned bricks, arising from poor mortar alone. 30

Brick Watching For small quantities, correct proportions of the sand and cement are carefully measured out and thoroughly mixed, dry, on a flat surface, often a large flat board. Good mixing is essential for a good mortar. Then the water is added gradually, mixing all the time to ensure all the particles are wetted. It is hard work, requiring strong muscles and deft hands to wield the shovel, and a sound understanding of what a good mortar should look and feel like. The man who mixes the mortar is an important part of the team, or gang. It is essential that the mixture be homogeneous, that is that the sand and cement are evenly mixed together throughout. Every little bit must be thoroughly wetted by the water, too, without over-doing it. A good bricklayer may justifiably reject a mixture that is too sloppy, or one that is not easily worked; but properly prepared mortar is a pleasure to use. It comes easily from the trowel, settles along the brick, and yields to the pressure of the bricklayer as the next brick is placed. When a machine is used the measured materials of sand and cement are fed in, and thoroughly mixed, and then the water is added, just the right amount. Again, cleanliness is important, and the machine needs careful washing out at the end of the day's work so that the blades do not become encrusted with set mortar. Most small builders hire a mixer, though they are now so modestly priced that many have their own. The jobbing builder can hire or buy a variety of small mixers. Electrically driven, or petrol-engined models are available from the merchants or equipment hire centres, and these small machines can be taken to the site in the contractor's lorry. Making the mortar is just as important as making the bricks, and the materials must be of the right quality, both the sand and the cement. It has to be emphasised that good clean water is essential on a building site for making concrete and mortar. Quantities are important, too. The water is taken up by the bricks, depending upon the mix and the porosity of the bricks and their condition. Too much water produces a slushy mix; and with too little the particles are not properly wetted. It may seem a simple matter to stir up some cement and sand and slosh a lot of water on it; but it does require care. When mortar is placed its consistency will control the ease with which the bricklayer works. After it is placed, the mortar undergoes two changes. Firstly it stiffens by separation and loss of water. Then it undergoes a chemical change and hardens. It takes a little time for this to happen, and the process cannot be hurried. Undue water loss by suction can be minimised by wetting the bricks before they are laid. 31

Brick Watching If the mortar is too sloppy it is difficult for the courses to be properly shaped. It must be sufficiently stiff but at the same time yielding as each brick is laid and then pushed into precise position. So the making of the mortar is a matter requiring understanding and skill. The man who mixes the mortar is no fool. The three lines of manufacture, then for brick structures, are the bricks, the mortar, and the water supply. For these, clay, sand and cement are the necessary elements. Brick-watchers can learn much about the brick manufacturers and the builders from close inspection of the structure itself. First class work shows clear differences from the second-rate.

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Bricklaying The process of building in brick begins with the arrival of bricks on site. Nowadays lorries that can cope with ten thousand bricks, and which are equipped with hoists, pick up loads from the brickyard, where they are stacked in piles each containing several packets of bricks. The stacks have been built up by the use of forklift trucks, that modern blessing. Simple to learn to use,and nimble and easily manoeuvrable, the forklift truck makes short work of what was once heavy manual labour. At the site, the hoist on the lorry is used to lift off the blocks of bricks and put them down just where they are to be stored. The whole process is simple rapid and cheap. The bricklayer can have the bricks delivered to him by forklift truck or hoist. For small jobs a labourer can carry the bricks to him in a hod, a beautifully simple wooden holder which rests on the shoulder, with a pole that hangs down near the hand. There are fewer hods to be seen now, and lightweight electric hoists do the job very well; but the hod is one of those tools that superficially are so simple, and are actually a delightful demonstration of man's ingenuity. They can be a source of danger if some careless handling should cause the bricks to slide off and tumble earthwards. You may come across other types of hod in various countries around the world, though they are fast disappearing except in the more remote areas. One cunningly simple arrangement is a flat board that is cut out to fit round the neck of the labourer, the bricks being so disposed on this surface as to achieve a balance while the load is being carried from one place to another. Mortar is needed in quantity, and as the work proceeds both bricks and mortar travel further and further upwards. In the old days a "brickie" and his mate often worked together for much of their lives, and knew one another's characteristics so well that the work went smoothly, much as the driver and stoker of a steam engine learned to work closely together. The mortar was prepared as and when required, just the right amount at the right time, so that the bricklayer was never kept waiting, yet the mortar didn't lay around, going off before it could be used. It can be instructive to watch a brick structure in the making, even quite a small one, to see how the materials arrive as required. Just as a good labourer keeps his shovel smooth, clean and free from material that makes it hard to use, so does a good bricklayer keep his trowel in a high state of cleanliness, and his line, plumb and level in good condition. In the world of building, as in other spheres, you can judge a craftsman by the condition of his tools. Half a century ago, an employer would ask to see the tools of an applicant for a job, and on that basis judge the skill of the man. Once you understand the reasons for laying bricks in a certain pattern you will more easily appreciate the brick structures you see. You might also spot the differences 33

Brick Watching between good and poor quality work, though you should not necessarily condemn the latter. For some odd jobs it isn't worth employing an expert. If you want some odd length of low wall for creepers to climb, or to have a rude appearance, then the rougher the better, within limits. We shall look first at what we can consider to be the most elementary, the least complicated bricklaying job, the erection of a short length of straight vertical wall. We shall assume that a suitable foundation or footing has been prepared,a level run of concrete wide enough to provide a sound base on which to erect the wall. Such foundations are designed to spread the load of the wall to minimise subsidence when the load is applied. If you push a pointed stick into some damp soil or sand it may not take much force to penetrate; but if you try to do the same thing with a thick blunt stick it is harder. This is because the pointed stick is concentrating your force over a small area, producing a high penetrating stress. The blunt stick is spreading the load over a larger area, and the stress is therefore smaller. Thus, we can so design our foundations that the stress applied is well within the safe limits. The strength of a sample of soil can be measured in the laboratory with precision, and from this the safe working stress can be calculated. Knowing the load to be applied by the building, we can arrive at the necessary area of the footings. Usually these calculations are based on unit length of a wall, when a wall is being considered. So the width of the foundation is found, and the requirements met by spreading the load over a mass of concrete, stone or brick. If you like equations, then you may care to note that the width of the foundations, W, is given by the simple equation W = Load/f where L is the imposed load per unit length of wall, and f is the safe working stress on the soil. So the higher the safe compressive stress on the soil, the narrower the footings can be. There are limits in the use of such equations, of course, since a very narrow foundation might be unstable. Generally, for small buildings, there are "rules of thumb" for such things. The next task is the "setting-out", and for our purposes we shall look at what is wanted for a straight length of walling. Having decided on where the wall is to be built we put a peg in at each end of a line, fixing the line of the wall, and dig away the top soil, to make a trench suitable to receive 34

Brick Watching the concrete for the foundations. Nowadays there are nippy little digging machines to excavate a trench of the desired width rapidly, and even small building contractors often hire them to save money on labour. The range of equipment for hire has been greatly extended over the past few decades. A builder will set up "profiles", three pieces of wood nailed together like miniature goal posts, and use lengths of suitable line to connect them, providing a series of straight lines to which the digger can operate. The bricklayer will work to these as he lays bricks on the bed of mortar that has been applied to the foundations.

By working from each end, whole bricks can be used until they nearly meet. The remaining gap is filled by a "closer", a brick that has been cut to the right length. At one time a closer was struck from a whole brick by a suitable clout with the trowel. Now there are simple machines that will cut a closer, or shape a brick at any angle, with ease. They demonstrate the purchase one can get with a long lever. Power cutters are used too. It is unlikely that the first course will have open ends. It will usually have a "return" or corner at each end, for stability, or perhaps a pillar, or adjacent wall. The courses will key into such features. This first course demands accuracy, for if it wanders, or is not level, length-wise and across, the rest of the wall cannot run true. So great care is taken to lay each brick level, and align it accurately. It all looks so easy at the hands of a skilled craftsman, but proves very awkward when essayed by someone without the skill and experience that comes from long training and practice. When the second course is begun, the decision is taken as to the type of "bond" or pattern, and how the joints are to be made, that is the kind of "pointing", both very important. Looking first at the bond, there is a choice of several, but in practice the predominant ones are the "English bond" and the "Flemish bond". 35

Brick Watching The reason for these "bonds" is to ensure that there is no straight line of mortar running up through the wall, that is, the perpends are not in line, as this would be a line of weakness. At this stage it could be instructive to experiment with a number of bricks. However, it is much better if you try the following indoors, with a pile of suitable wood blocks, say a three or four dozen, each of the same proportions as a standard brick, though not necessarily the same size. A child's blocks will be admirable. First lay a block on its largest face. Then on top of it place another, and another, and so build a little tower of blocks, as far as you can. See how the stability decreases as the height of the tower increases. At first, with just two or three blocks, all is firm; but as more and more blocks are laid, however carefully, the pile starts to get wobbly. Eventually, the whole thing is so unstable that the slightest shake will cause it to collapse. The controlling factor for this instability is the ratio of the height to the cross-sectional area of the pile. Actually it is not just the area, but the shape of the cross-section too. In all columns this ratio, known as the l/k ratio, governs its stability. The letter "k" is a measure of the spread of the material in a section, and is called the "radius of gyration". You can increase this "radius of gyration" by building the column with a larger crosssection say starting on a square base formed by four blocks. You will find that such a pillar can be carried to a much greater height without disaster. If you have enough blocks you can start from a larger base, so that the cross-section is bigger, more spread out. You will soon be convinced of the value of a large value of "k". Now lay a row of blocks, say half a dozen, along a straight line on the floor, touching one another, and lay another row on these, face upon face. When laying this second row, if you keep the joins vertically above one another so the perpends are in one straight vertical line, you will soon appreciate that the wall is as unstable as the first pile of blocks that you built. However, if the joins are offset, so that the gaps are not in line, you see an immediate increase in stability. The blocks are locked into one another;they form a bond. Herein lies the simple secret of building in brick. Experiment with different ways of building with the wooden blocks, and in particular notice how stable a wall is when a proper bond is used. Try the effect of "stretcher" bond and "header" bond, and alternate courses of these. 36

Brick Watching See how a weakness occurs when vertical joins are aligned with one another. A few hours playing on the floor can teach you much about brick structures. To a certain extent a child learns the principles of stability during play with a box of wooden blocks. When you look at a plain brick wall, see how the vertical joins are arranged, running up in a kind of zigzag pattern. In good bricklaying the lines of mortar are clearly seen, straight and level, best seen by looking along them from one end. If you place your eye suitably, you can look upwards along the line of the vertical lines of mortar, and see how they too are carefully aligned. A well-built plain wall is a delight to those who know how to look at it. Returning now to the idea of the "bond", we have a wide choice of patterns, and some of these are illustrated. You will soon be able to recognise the different kinds, and notice that they all avoid positioning any vertical joins in line with one another. When the mortar is laid and the brick positioned, the excess mortar escapes from between the bricks, and the bricklayer removes the surplus with the trowel. How he does this is a matter of some interest, for this determines the type of "pointing". The simplest approach is to scrape the surplus mortar flush with the brick surface, so that the line of mortar is level with the wall throughout. The advantage of this pointing is that it is the cheapest, requiring no further treatment. You will see plenty of this about, everywhere. However, there are other kinds of finish that add to the beauty of the finished brickwork. Some of the ways of dealing with the joints between bricks are illustrated. Good pointing is a matter of pride with the skilled bricklayer. However, it must be realised that time spent on anything other than the strictly utilitarian aspects does incur extra expense. So the inner faces of walls usually have nothing more than flush pointing at best. Deviation from flush pointing is carried out before the mortar has set, so that when all has dried out and finished the beautifying effect of the different types of pointing can be seen and appreciated. A cavity wall is one in which there are effectively two separate and parallel walls with a space between, to provide insulation and stability. Sometime the inner wall uses building blocks instead of bricks. The pointing for theses is flush.

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When a cavity wall is erected metal strips called "wall ties" are laid across the gap at intervals, in the soft mortar, so that they tie together those two separate walls. These are of wire or strip, twisted so that they cannot carry moisture across the gap. You will not normally see these except during construction or demolition. Look out for them. They are examples of simple ingenuity at its best. Any water attempting to travel along them is unable to climb the slope of the fixtures. They are protected against rust of course, usually galvanised, i.e. coated in zinc.

The ascent of moisture from the ground through the bricks is prevented by a damp proof course, usually referred to as the "d.p.c.", an impermeable layer placed between the lower courses. The choice is wide, including slate, asphalt, glazed stoneware slabs, lead sheet, or PVC. Any material that prevents the passage of water may be used, though not those that might be affected by the mortar. You can see the edges of these dpc's from the outside, a few inches above ground level. There are occasions when a bricklayer is required to incorporate a vertical dpc, and in such cases impermeable material is taken up the inside of the wall to protect the inner wall against the transfer of water from the outside.

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Tops of walls which do not support roofing work are vulnerable to rainwater, and are usually protected by coping courses, consisting of bricks which are sloped to shed the water, or by special coping bricks, often flat underneath and curved on top. These bridge the upper course, and rainwater drips clear of the face of the wall itself. Specially shaped bricks are often to be seen in pillars where the cross-section changes. They are usually arranged so that water running down the pillar is deflected outwards at the change of section. Not only does this help to protect the lower part of the pillar, but also the gradual change of section avoids the stress raiser occasioned by a sudden change.

The craft of a tiler differs from that of a bricklayer; but clay tiles are made in the same way as bricks, from the same materials. They are not usually laid in mortar, except when used for floors, but hung on battens, lengths of timber nailed in place to receive them, on walls and roofs. Roofing tiles look delightful when newly laid; but when old roofs reach the stage where they begin to sag artists find them particularly picturesque. The bricklayer himself will sometimes make use of tiles here and there, and you may spot them, for example in fireplace surrounds, and other places where they are used for decorative effect. A coping course of sloping tiles is attractive and effective. Sills are frequently tiled, too, and are laid with a fall to shed rain.

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Brick Watching Specially shaped and moulded bricks are often built into structures, beneath window ledges, at the tops of pillars, and wherever a little fancywork adds to the attraction. Brick stockists publish catalogues showing the choices available for the benefit of architects and builders. Look out for these, especially in buildings put up in the Victorian era. You can find these in humble cottages as well as in mansions. It is well worth looking upward towards the roof in some of the older gracious homes. Fine decorative brickwork can be seen in the chimneys. The chimney is fast disappearing as an architectural feature; but in their day some magnificent examples were built. In many houses, where fireplaces were put into most of the rooms, the chimney stacks were wonders of craftsmanship, each chimney being different in appearance. You may sometimes see tall narrow chimney stacks which over the years have bent over like bananas. It isn't really the fault of the bricklayer. A chimney stack is a stationary object, and there it stands while the sun rises,and slowly bakes one face, the southern one in the northern hemisphere, for hours at a time. Then comes the cool of the night, sometimes below zero. So the pointing on the southern face undergoes a daily cycle of heating and cooling, day after day and year after year. If any moisture gets into the joints the changes can impose serious stresses in the exposed structure, and the mortar will deteriorate. As a result, on an old cottage the single chimney stack may bend over like an obsequious servant, and some are braced with steel rods. Although the brick is a simple lump of baked clay a man of imagination could produce amazing variations in form by cunning changes in the arrangement of each succeeding course. Old chimneys are a brick-watcher's delight. One more item should be mentioned here, the requirements for retaining walls. Water falling on the soil behind a wall percolates downwards, and eventually the material is soaked. This then imposes a hydrostatic pressure on the wall. For a low wall this is not very great, but for high walls the force can be considerable. The resultant force from this pressure is exerted about a third of the way up, where it has a significant leverage over the base. The overturning effect can push over the wall, and steps are taken to prevent this.

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Brick Watching You may sometimes see holes in the wall, low down, containing short lengths of pipe, which drain away any water which might otherwise accumulate behind. Further, the bricklayer will sometimes be required to build a wall with a "batter", or backward slope,to improve stability, or buttresses to take the horizontal load. Buttresses are sometimes used to prop up a wall which is beginning to tilt, from subsidence, or the powerful action of the roots of trees planted unwisely too near. A buttress need not be ugly, and can add charm to an old wall. Look out for them. They are of great variety, and usually incorporate sloping courses. All these points are to be noted when brick-watching. Further, you may sometimes come across fine examples of the bricklayer's art in the form of arches, circular openings, decorative features of all kinds. Modern methods using concrete blocks and slabs have not killed off the need for skilled bricklayers. There are courses at many colleges to teach the art and the craft, and plenty of young people anxious to learn. Bricklaying has always had an appeal for the amateur, particularly for those in retirement. It is an occupation with a special attraction for those who enjoy the open air and the creativity associated with seeing a structure grow beneath one's hands from a pile of bricks. You may well be attracted yourself. If so, get a good pair of gloves, for bricks are hard on one's hands ....

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Examples Bricks of different kinds are to be found in most parts of the world, so there is little difficulty in finding some examples of various bricks and brickwork wherever you are. Even in areas where clay is unobtainable you find bricks imported from other parts, sometimes distant parts, and used locally. The Eskimo constructs sound igloos from ice-blocks cut to shape. The basis of construction is the same in general, though mortar is not needed. The fundamental requirement of all building in brick or block is that no vertical joints, or perpends, are immediately above one another in the same course, though this seems to be of less importance in an igloo. The blocks fuse together in the sub-zero temperatures, and a firm structure results.

In urban areas all over the world many of the buildings are of concrete or steel, but brick is usually preferred for residential parts of the cities. Sometimes the inner wall is of breezeblock, or lightweight foamed material; but brick on the outside is pleasing in appearance, and practical. In some parts of the earth, in particular the Americas, dwellings and shops may be built in timber with a facing of imitation brick. From a distance the effect is that of an ordinary brick building, though the fire-resistant qualities of the structure might leave much to be desired.... Walls in brick are common, and many of these have stood for a very long time. In the more rural areas you may come across long brick walls surrounding large estates, put up in the days when labour was cheap and plentiful. In time such walls fail not from any inherent weakness of the bricks themselves, but from ground heave or earth movement due to the roots of nearby trees pushing their way under the foundations. If the coping is defective or incomplete in parts, this too can 42

Brick Watching lead to failure. Rainwater can get into the joints, where alternate freezing and thawing can quickly destroy the wall.

Poor pointing, too, can allow weeds to take root between the courses and push the bricks apart. Once the plants have a hold, their movement opens up other spaces for grasses and other plants to invade. For the brick-watcher this is not without some degree of interest. Such miniature "gardens" can be attractive, if it isn't your wall that is being broken down. They provide a colourful and seasonal variation in the appearance of the wall. When the wall finally disintegrates there is the invasion by the mosses which follows. These are astonishingly complicated plants when viewed under a magnifying glass. All they demand is a little moisture, and perhaps some shade. Then they will cheerfully wave their little flags and sit there crowded together in comfortable sloth, forming a soft emerald cushion to soften the outlines of bricks and stones. In many of the older estates, there are no longer the large numbers of servants. Formerly, there were plenty of gardeners and maintenance staff to look after the walls and buildings and to keep an eye open for incipient defects. So in old estates there are usually examples of crumbling brickwork to be found, and tilting walls buttressed to stave off collapse. Some of the fine old trees, originally planted too near to walls, have had to be cut down. There are signs of this in many large estates. An ancient oak may have started as a slender stripling, but in time it grows to an enormous size, and its roots travel far beneath the surface of the soil in search of water and nutrients. Where the roots surface you can form a good idea of their size and strength. 43

Brick Watching Perhaps the most conspicuous use of brick is seen in tall industrial chimneys. Even though in some cases the smaller ones are in steel, and many have been demolished, there are still plenty of brick specimens to be seen. They provide interesting examples of the brick-layer's art, for they are mostly circular in section, tapering towards the top, and finished with copings which can be examined through a pair of field glasses. The function of a chimney is to take smoke and gases up to a level where they can be more readily dispersed by the wind. A the bore of a chimney forms with the outside air a kind of U-tube, and as the levels in a u-tube tend to equalise so do the pressures within and without the flue. The air around the outside of the flue is cooler, and hence denser, than the gases inside, so the inner gases "float" upwards, driven by the denser fresh air moving in at the base. This is the draught that carries away the unwanted fumes. Broadly speaking, brick chimneys are usually cylindrical, and the volume V of the cylinder is then given by V = pH D_ / 4 where H is the height and D the internal diameter. This is a very rough approximation, for D is not normally constant, and an empirical relation is one in which the crosssectional area varies inversely as the square root of the height. There are other empirical formulae applicable to chimney design, and you can find these in the literature. The volume of gases within the chimney moves with a velocity v, say, and this is the speed with which the plume leaves the top. A volume V of fumes issues forth in time t, given by t=H/v Put another way, every t seconds a quantity of smoke and/or steam equal to the internal volume of the chimney is released into the air, with a vertical velocity v. This plume will often include soot and cinder. As the plume is bent over by the wind and begins to flow more nearly horizontally it loses speed. When the speed falls below the transport velocity for the particles they fall, and are deposited in a swathe downwind of the chimney. Over the years, in places where the prevailing direction of the wind is fairly constant, the effects may sometimes be seen on the roofs nearby. If you look at the top of a chimney the smoke plume can indicate by the angle it makes with the horizontal the strength of the wind up at the top, as well as the direction. The "buoyancy" of the flue gases is due to their higher temperature, above that of the ambient atmosphere. A chimney will not "draw" till a temperature difference exists. 44

Brick Watching This is why it used to to take a while to "fire up" a steam locomotive engine. The earlier locomotives had a tall chimney but the later ones had stubby ones, and means were employed to stimulate the draught. The hot gases have to flow up this cylinder at such a rate that an adequate draught is maintained through the furnace. If the diameter were too small the air supply would be restricted, leading to incomplete combustion. If too large the discharge would be slow, and the gases not properly dispersed. In some cases forced draught may be achieved with the use of fans. The height H should be such as to carry the products of combustion clear of adjacent buildings. However, height is expensive, so unnecessarily high chimneys are a waste of labour and money. Brick is a good thermal insulator, and as such is a good material for a tall chimney. The gases do not lose heat as they ascend, once the chimney is warmed, helping to maintain a steady draw. When height and diameter have been decided the foundation and the numbers of bricks in the lower courses can be settled. The lower courses carry the weight of the whole chimney, and must be substantial. Higher up, the load is less and the outer diameter correspondingly smaller. You can see the enlarged base and the upward tapering shape in industrial chimneys. Much can be learned about brick chimneys when they are demolished. Some notable video footage has been recorded of chimneys being felled, and these are worth studying. A chimney can be regarded as a column or, when caused to tilt, as a vertical cantilever. To fell it, one needs to weaken the base by cutting out the lower courses on one side. This causes that side to push down and thus tilt the whole structure. It is then a cantilever, with a weakened hinge, and collapse follows. Careful planning is needed, to ensure that the operation is safe, and that the debris falls where intended. There is some fascinating film of falling chimneys, made during felling operations by that famous steeplejack Fred Dibner. With a pair of field glasses you can examine the coping courses at the top of a tall the chimney, and perhaps see the lightning conductor running down the structure. This is a thick metal strip connecting the top to the ground. It provides an easy path for an electrical current to flow directly to earth, rather than through the brickwork of the structure, thus minimising the risk of serious damage through the high temperatures occurring when such a current passes.

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Brick Watching The erection of a large industrial chimney is an expensive undertaking, and its life may be shortened by changing demands and changing methods. During its lifetime some maintenance is normally required, done by steeplejacks, always a good spectator event. Factory chimneys are plain in appearance, but domestic chimneys on old houses are often fancifully decorated, a delight for the connoisseur. Here the art of the bricklayer produces a practical pleasing effect. The Victorians were keen on their chimneys, and even on modest dwellings you can sometimes see the results of the bricklayer's art above the roof. You may sometimes come across metal chimneys with a helical fin running up round the outside. The purpose of this is to minimise wind-induced vibrations. As the air moves past a cylinder it sheds vortices alternately clockwise and anticlockwise downstream, and transverse vibrations result, like the wobble of a stick drawn rapidly through water. This is an effect connected with the Strouhal number, a non-dimensional constant familiar to those who study hydrodynamics. You will not see this feature on a brick chimney, which is a much more rigid structure. Generally speaking, metal chimneys are among the shorter, smaller specimens. The high ones are nearly always in brick. The old ones were considered to need a minimum height of about a hundred feet, which is something over thirty metres. Metal chimneys often require stays, cables running down to anchorage points some distance from the base, a feature nor seen in brick chimneys.

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Brick Watching On old-established farms some of the more ancient barns may be worth a second look. Here you are likely to find examples of old bricks, perhaps in English garden bond, or a mixture of bonds, with pointing in lime mortar, crumbling away or patched up with a sheet of corrugated iron. This may seem ugly to some, but many people like the contrasting colours of rust and brickwork. In some areas cob walls have been used, and where they have suffered from the elements, a few bricks may have been used to patch up the holes. They are worth a look, to identify the type of brick used.

The lintels, i.e. the beams across openings, may be of heavy timber or, sometimes, brick. You might see some in which the bricks are of unequal dimensions, indicative of the farmer's thrifty outlook, using up what is to hand. In the odd outhouses or pig accommodation, using old bricks, and working with unskilled labour, little attention was paid to precise alignment. The courses might look wobbly, but they served their purpose. A walk along a country lane can reveal odd lengths of wall with mixed repair work in stone and brick. The bricks may be fitted in higgledy-piggledy with little regard to the niceties of bonds. The interest here is in the types of brick to be found in some of this patchwork. A towpath is a good place to find canal tunnel openings, and these are nearly always in brick. The bridges, too, over the canals are usually delightful examples of cunning brickwork. Such bridges were normally built over a timber framework, or shuttering, which was removed after the brick arch was completed. If you peer down an old well, you may find a brick lining, running right down to the cool wet depths. These bricks will probably be old ones, for newly constructed wells are 47

Brick Watching rare nowadays. (You may discover, too, that the water tastes much better than the liquid delivered by the local Water Company, for it has not been subjected to dosing, flocculation, filtration, and transportation through rusty pipes. In old gardens you may come across paved strips where the ground is sometimes muddy. Often the bricks used are perforated ones, so that the grass grows through. This provides firm standing whilst appearing to be a grassy area. Bricks laid like this can carry a substantial rolling load,and can convert a soft strip of ground into a sound pathway or track. Soft yielding ground can deal with heavy traffic if broken bricks or hard-core can be laid. On building sites a few lorry-loads of old bricks may be tipped onto the ground along suitable paths on green sites to provide access roads. Buyers of homes on building estates may find that their first few years of gardening call for some pretty heavy spadework as a result.

For the brick-watcher, though, even broken bricks can tell a story. The size, shape, and colour can provide clues to identification of where and when the bricks were made. It is also of interest to note, in the case of broken bricks,the mode of failure. Brick material does not really fail in shear, even though a shear stress is put upon it. Shear stress induces tensile and compressive stresses at an angle of forty-five degrees to that of the shear. It is the tensile stress that causes failure. Examination of the break may reveal a weakness in the form of an inclusion in the clay, especially in some of the older bricks; and the line of fracture can indicate the nature of the original loading that led to failure. It is likely that among discarded broken bricks or hard-core you can see bricks of differing degrees of hardness. The so-called "engineering bricks" are so much harder that you may find them whole, or perhaps with a small chip, among others that are broken into small chunks. 48

Brick Watching

For moulded bricks there is a good selection to be seen in small terrace houses built around the turn of the eighteenth and nineteenth centuries. Small imitation columns in the Ionic and Corinthian styles, intricate floral designs and figures, and fancy patterns in great variety are to be seen adorning the fronts of small town houses. The back walls may be quite plain, but the front can be intriguing. Looking at bricks can take you from mansion to brickyard, from cathedral to tip, in all sorts of places. It is largely a matter of keeping one's eyes open. The brick is a remarkably useful object to the ingenious person, and for this reason you may come across bricks in some unlikely places. For example, a table with a short leg may be induced to provide a level surface by shoving a brick under one leg, though you are unlikely to see this in a drawing room. A workman may push a brick under a support to raise it, or to provide more area to spread the load. A brick might be handy for propping open a gate. Again, a lavatory cistern flushes an amount of water determined by the capacity of the cistern. This amount can be reduced considerably by placing a brick in the cistern. In some places this is advocated in time of drought, though it does reduce the efficiency of the flush. Although, earlier, the use of mortar was considered, bricks can be used without mortar to produce "dry-stone walling". This method is not as strong as properly bonded and pointed walling, but is adequate in gardens for low walls, and some unevenness can add to the charm of such structures.

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Brick Watching Attractive effects can be produced by leaving gaps here and there to accommodate flowering plants of carefully selected kinds. It is a simple and rapid method for putting up decorative walls of modest height. A couple of bricks in a bag make an adequate anchor for a small boat in calm water; and bricks have been used in plenty for ballast in larger vessels. They are dense, so that a few hundred can make up enough weight in the holds to do a useful job of minimising heel. At one time they were widely used for this purpose since they could be sold at the end of the voyage.

Beneath the ground floor of many buildings there exists a hidden world of brickwork. Wooden floors need adequate ventilation if they are not to succumb to rot. To achieve this, the floors are supported well clear of the earth, and insulated by a damp proof course in the brickwalls. Fresh air circulates under the floor via special perforated bricks, which are called "air bricks". You can see these by looking at the outside wall, low down, on all the sides of the house. They are easily recognised, and are not always of the same colour as the other bricks. They may be of metal, made to same dimensions of the common brick, with a pattern of perforations. They are a vital part of the building for without them the air below the floor would be static, and undesirable growths of rot would soon destroy the floor itself. Good maintenance demands that they be kept clear, and free from weed growth in the soil outside. In a number of games for children the potential of the brick has been exploited, providing small plastic or wooden blocks from which the child can build simple structures. Such toys are instructive and diverting, and an adult can by their use discover the value of bonding and the need for quoins at the wall ends.

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Brick Watching Bricks can be found in many seemingly unlikely places, and the keen brick-watcher will find interest in poking around here and there. Taken all round the brick might be considered as one of the most useful inventions of mankind, and it is hoped that the reader may find much pleasure in seeking and finding examples. The content of this book is not intended to be exhaustive. Nor could it be. The intention is to whet the appetite only and stimulate the sense of curiosity. There is plenty of information in books, papers, and journals to extend one's knowledge, and much to be gained in conversation with those who make and use bricks everywhere. New methods of building arrive constantly, but the brick is not merely holding its own. Its value is increasingly being recognised. The brick-watcher need never feel at a loss.

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Glossary Abutment One end of an arch or vault, taking the lateral thrust. Air Brick A brick with holes in it to allow air to pass through for ventilation. Essential below a damp proof. Arris The sharp edge formed where two surfaces meet. Bat A brick or a piece of brick, usually referred to as a brickbat. A three-quarter bat is one that is three quarters as long as a whole brick. Batter The amount by which a retaining wall leans back, so contributing to the stability. Birdmouth A vertical angle that is recessed, or internal. Bolster A large chisel used by a bricklayer, sometimes called a boaster. This hand tool has been largely replaced by a brick-cutter, which uses a large leverage to cut a brick neatly. Bond The arrangement of the rows of bricks to avoid creating vertical lines of joints. The two commonest are the English, or Old English, and the Flemish bond. These, and others, are referred to in the text. There at least thirty different ways of arranging bricks so as to ensure no vertical joins in adjacent courses are together. Bullnose A brick with one of the arrises rounded. Buttress An arrangement of bricks projecting from the face of a wall to provide lateral support. If the buttress does not make contact all the way up the wall it is referred to as a flying buttress, an attractive feature in of a building. Cavity Wall A wall consisting of two walls, a kind of double wall, double wall eaves with a gap between. This method of construction provides insulation (sound and heat) and additional strength. Centering The temporary frame, often of timber, used to support an arch during construction. After the keystone has been fitted, and the mortar has set, the centring, or shuttering, is struck or removed. Centring is used wherever temporary support is needed, for example for concrete walls while the concrete is poured. Cill The lowest horizontal part of a door or window opening. Closer A brick of non-standard size which is used to close a gap in a course. The closer may be made by striking a brick with a trowel, simple in the hands of the expert bricklayer. Closers in adjacent courses are not normally laid adjacent to one another. 53

Brick Watching Corbel A support projecting from the face of a wall. Course The bricks in a horizontal row, one brick high. Crinkle-Crankle A thin wall, getting its stability from being serpentine in plan. Such a wall can be built only one brick thick, even half a brick if not very too high. Damp-Proof Course A course of impermeable, i.e., waterproof material laid a little above ground level, to prevent moisture travelling up a the wall. Sometimes a d.p.c. is laid vertically to prevent the horizontal movement of water. Dentils Tooth-like projections formed by laying alternate headers so as to jut out from the face of the wall. Dinging A term used to mean axing old brick facings to form a new face prior to refacing. It is sometimes applied to rubbing brick facings with a piece of brick of the same colour, and sometimes to smoothing the face of brickwork. Dog-Tooth Bricks laid diagonally so that the corners project. A decorative course usually seen high up in a building. Drip A small groove in the underside of a course of bricks so as to stop water running back into the wall, usually found in a cill. Efflorescence A disfiguring white substance on the face of brickwork, usually due to the presence of salt. It appears during or shortly after the laying of bricks. It arises from the movement of salts to the outer surface of a brick. The brick-watcher is unlikely to see this on well-established walls, as it usually vanishes of its own accord, or is scrubbed off with a stiff brush. Engineering Bricks These are bricks of high density and accurate dimensions, strong and of low porosity. Facings Bricks of good quality and appearance, suitable for exposed faces of brickwork. Fireclay Bricks Bricks of a refractory clay, rich in alumina and quartz, used for firebricks in grates. Flaunching Mortar laid along a ledge to prevent ingress of water. You can see this at the top of chimney stacks. Flettons A comparatively cheap brick, the clay for these bricks is moist, with a high carbon content, helping the burning process.

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Brick Watching Footings The courses of extra width, stepped outwards, at the foot of a wall, to reduce the stress on the foundations by spreading the load. The brick-watcher may not often see footings, except during construction, as they are normally below the surface of the soil. They form the base on which the walls bricks are built. See Foundation. Foundation Brick, stone or concrete construction to form a kind of platform so as to spread the load of the structure over an area greater than that of the walls themselves. The ground can carry a stress which depends upon the type of soil or rock. Firm rock can carry a large stress, and the foundations need not be extensive; but on softer material which would fail under a large stress, the footings must be correspondingly increased to avoid the risk of subsidence. Frog The depression on the largest face of a brick. It normally extends about a fifth of the way into the brick, and accommodates the mortar surplus to the requirement of the joint. When set, the mortar, being continuous from the joint to the frog, resists sideways and end-ways movement of the brick relative to the one above it by its shear strength. Glazed Bricks can have a glassy surface when the exposed stretcher or header face is suitably coated and then fired at a high temperature Groin The groin is the edge formed at the intersection of two vaults. Grouting Filling spaces in the joints mortar with a thin mortar, normally carrying no stress, but improving the general appearance. Grouting is usually carried out after the wall or other structure is completed, but is not applied with certain kinds of pointing. Headers Bricks laid in a wall so as to show their smallest faces, that is, across the wall. Impost The brickwork between the arches. Isometric A method of drawing which considers the building tilted up at an angle of thirty degrees. The outer edges of a cube, drawn in this projection, run off at equal angles, and measurements along the three axes are to a uniform scale. With practice, it is easy to make a quick and accurate sketch using isometric projection. Jambs The brickwork at the sides of openings for e.g., doors and windows. Keystone The stone at the crown of an arch, which in effect binds the arch together. Until the keystone is in place the arch has no strength. It is so important that it is often decorated, and made to stand proud of the other arch bricks. Larrying If a soft or semi-liquid mortar is laid on the work, and then a brick is laid and pushed along so as to push a ridge of mortar before it, this rises to fill the vertical gap. It is a quick method, but not considered to be the best class of work.

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Brick Watching Mortar The sand-cement mixture, usually of sand and cement, that separates adjacent bricks. Mullion The thin vertical shaft of brickwork between adjacent windows. Nogging Decorative infill of brickwork between timber frames. Parging Plaster, roughcast. Paviors Special bricks for paved areas. Sometimes ordinary house bricks are used, though they are not very hard wearing. In gardens they can look attractive, even more so when worn. Perpends The vertical joints in brickwork. If vertical joints in adjacent courses are aligned with one another they form a line of weakness along which the wall may fail. The perpends are vertically aligned with each other in the best work. Pilaster A square pillar which is square or circular in section, projecting from the face of a wall, often moulded. A pilaster TA pilaster his need not be parallel all the way up. The shape of the section may change at different heights. By arranging the courses appropriately the whole pilaster may be given a twisted appearance or decorated in other ways. Plumb Vertical, upright, used as a verb and an adjective. The old bricklayer's plumbrule was a wooden straightedge with a central slot in which a leaden bob was freely suspended on a string, a simple, economical and effective tool with a long history. Pointing The lines of mortar between the bricks. The ways of finishing the pointing affect the appearance of the finished structure. Quoin An angle, such as the external angle of a wall. Quoins The external corners of brick walling. Raked Joint A joint between courses, the mortar raked out a short depth, either as a decorative effect or to provide room for re-pointing. It is also effective when a rendering is to be applied. Rendering The stucco or plaster sometimes applied over brickwork. Shuttering See centering. Sleeper Walls Walls below floors with alternate headers omitted so permitting free flow of ventilation air. 55

Brick Watching Soldier Course A course of bricks set on their smallest faces, or ends, resembling a file of soldiers. Squint Coin A vertical angle in brickwork that differs from a right angle. Squints Specials with one corner missing, for decorative use. Stretchers Bricks laid with the longest edges faces aligned with the face of the wall. Tie Plates Metal plates at the end of strengthening ties, often circular or decoratively shaped. Usually retained by large nuts which are tightened when the tie has been heated. Contraction of the tie on cooling then exerts a pull on the walls, to remove or reduce a bulge. Ties In a cavity wall, the two leaves are connected by ties, usually galvanised iron, laid so that the ends of the tie are embedded in the mortar. They are put in at intervals of a few courses, and serve to tie the two parts of the wall together. The brick-watcher will see these only during construction or demolition. Voussoirs Wedge-shaped bricks so tapered as to fit in with the curvature of an arch. Weep Hole A small hole left deliberately in a wall to allow the escape of moisture.

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Some Common Bonds

Stretcher bond

Header bond

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Flemish bond

Diagonal bond

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Herring-bone

St. Andrew’s Cross

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Napkin bond

Quetta bond

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Different kinds of pointing

Weather

Flat jointed

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Bucket handle

Struck

Tuck

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Overhand struck

V-tool

Y-tool

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Half-tuck

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Further Reading Adams, Prof. Henry, M.I.C.E. This is an old book, published near the start of the twentieth century. Much has changed in the building industry since it first was issued. Yet it is full of good useful knowledge which has relevance even today. It was a classic book in its time, and is still highly regarded. His chapter on brickwork is excellent. It may be difficult to get your hands on a copy now. Hendry, A.W. Structural Brickwork. Macmillan Press, London. Kempe Kempe's Engineers' Year Book is not devoted solely to bricks and brickwork, but covers a very wide field. It is well worth dipping into the pages and making happy discoveries. Plumridge and Meulenkamp have produced a wonderful book, called, simply, Brickwork, pub. Abrams. Every serious brick-watcher should see a copy. It is a classic of its kind, beautifully illustrated. It is too large for the pocket, but good for browsing, at home. Wight, J.A. Brick Building in England from the Middle Ages to 1550, pub. Baker. Pleasant and informative reading. The Standards Institutes in many countries provide useful information on many aspects of brickwork. Libraries maintain updated lists of these. The Brick Development Association in Britain, and similar publications in other countries can provide the latest news about progress in the industry. Builders' merchants sometimes keep copies of building journals. These are normally free, and keep builders and others abreast of new products. They are worth investigation. Apprentice Young bricklayers use textbooks giving details of methods used, teaching the basics and advanced knowledge. Publishers of technical books issue lists of these, from which titles can be selected of relevance to brickwork. The adoption of metrication in the building industry has in some measure made it necessary to allow for this in reading some books, reports and papers. If you are not familiar with the Imperial system of measurement you may find this a hindrance in dealing with older buildings.

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The metric size for bricks seems to have stabilised at 215 x 102.5 x 65 mm. (approximating to 8_" x 4" x 2_") though you may find that this is may not be applicable to countries outside Europe.

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Brick Watching Edmund W. Jupp The aim of the "Watching" series is to draw attention to some of the very interesting items around us, things that perhaps we don't notice as much as we might. The first was "Bridge Watching", and when this was put "on the Net" it produced, to the surprise of the author, such a pleasant flood of e-mail that another was written, called "Water Watching". This, too, was kindly received. So it was tempting to continue with the theme. Brick-watching is an inexpensive pastime, which can turn an old brick wall into an exciting find, and bring to your attention the fascination that is hidden from those who look but don't see, or perhaps see but don't look. It is taken for granted that everyone knows that a brick is a lump of clay moulded into a rectangular block and then baked; but there is of course much more to it than that. Armed with a little knowledge, every brick structure is an item of interest, something to be noticed, perhaps to be jotted down in a record, or photographed, drawn, painted, remembered. The author hopes that this gentle approach will provide some insight into the esoteric world of bricks, and will increase the pleasure of finding and studying the many brick structures (including the multitude of fascinating ruins) not only locally but all over the world. It might even convert the reader from being indifferent to becoming enthusiastic. Author Edmund W. Jupp (BSc (Eng), FIMech E) was born during the First World War in Sussex, England and received his early education at Brighton. After service in the 1939-45 war he worked in engineering and education, and travelled widely. He was appointed Principal of the Technical Institute in Guyana.

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