Brickwork and Paving E-Book

Michael Hammett

• Herausgeber: Crowood
• Kategorie: Lebensstil
• Sprache: Englisch

Seitenzahl: 229

Veröffentlichungsjahr: 2013

Beschreibung

This is a comprehensive guide to clay bricks and mortars, their physical and aesthetic properties, and their use in a wide range of building projects. Clear, accessible text, supported by full-colour illustrations and an extensive glossary, provides practical instruction in choosing, using and making the most of these highly versatile and durable building materials. Written for both the DIY enthusiast and for those wishing to specify brickwork or to check that it is being done correctly by professional builders, the book is an invaluable source of information and reference for anyone involved in building work. Covers basic bricklaying techniques, tools and equipment, dimensions and setting out, building straight and curved walls and building simple arches, bonding patterns, brickwork as cladding, and foundations. For paving work, includes laying patterns, steps, drainage, sand bedding and mortar-jointed paving. Also covers maintenance and repair, including dealing with water penetration, replacing bricks, repointing mortar, cleaning and artifical weathering.

Leseprobe

First published in 2003 by

The Crowood Press Ltd

Ramsbury, Marlborough

Wiltshire SN8 2HR

www.crowood.com

This e-book first published in 2013

This impression 2005

© Michael Hammett 2003

All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publishers.

British Library Cataloguing-in-Publication Data

A catalogue record for this book is available from the British Library.

ISBN 978 1 84797 662 8

Illustration credits

All drawings are by Claire Upsdale. The assistance of the Brick Development Association is acknowledged in their preparation.

The author is grateful to the following companies and individuals for the supply of and permission to reproduce photographs as follows. Baggeridge Brick plc: pages 6, 101, 102, and 111; Belle Group: pages 37, 38, and 118; Bovingdon Brickworks Ltd: page 23; Brick Development Association: pages 32, 54, 72, 79 (bottom), 80, 110, 113, 114, 115, 121 and 122; British Cement Association: page 36; Building Cosmetic Services: page 143; Sue Duncan: page 7; Freshfield Lane Brickworks Limited: page 18; Hanson Brick Europe: page 12; Kingscourt Brick: page 48; Caroline York: page 8; and The York Handmade Brick Co Ltd: pages 21 and 123.

All other photographs are by the author who also acknowledges The National Trust for kind permission to reproduce the picture of Tattershall Castle (page 10) and to Mr Christopher Parker for kind permission to reproduce the picture of Faulkbourne Hall (page 11).

Contents

1 Introduction

2 Brickwork Materials

3 Bricklaying

4 Brickwork Masonry

5 Paving

6 Maintenance and Repair

Glossary

Further Reading

Useful Contacts

Index

CHAPTER 1Introduction

Brick is an important building material in many parts of the world. In Britain, brickwork masonry has become a particularly well-established, well-developed and versatile form of construction. Because of its attractive appearance and superior properties of robustness, durability and low maintenance, it is the most popular material for building the external walls of houses. Brick is also appropriate for garden landscape features, especially when used in conjunction with clay pavers.

The successful application of brick depends on a basic appreciation of the variety of products included under the general description ‘brick’ and also on the nature of brickwork and how detail design affects appearance. This book provides informative comment on these matters, guidance on specification and basic information on the techniques used in simple brickwork for house and garden construction.

Over 90 per cent of bricks used in Britain are clay bricks. Bricks are also made of concrete – crushed rock aggregate bound with Portland cement. Sand, lime and crushed flint are used to make calcium silicate bricks, which are also known as sandlime and flintlime bricks. In some countries, bricks made from these alternative materials have a greater share of the overall market than they do in Britain.

Pavers are made of clay, but concrete pavers have the lion’s share of this market as they cost less to produce. The information and comments in this book are primarily concerned with clay bricks and clay pavers, but many of the comments and descriptions of work apply to all material types. Manufacturers’ recommendations should be followed on matters of detail specification.

Bricks are an ideal material in the domestic environment.

Garden walls and paving.

SCOPE OF THIS BOOK

The aim of this book is to provide information and guidance for general readers who are attracted to brick and would like some help in understanding the nature of bricks and mortar. It deals with the proper specification and construction of brickwork and brick paving in houses and gardens. Some detailed description of the tools and procedures involved in bricklaying and paving are included, which should help DIY enthusiasts expand their technical appreciation of brickwork, but the book is not primarily an instruction manual for craftsmanship training. It should assist readers to specify work and check that it is being built correctly by employed builders.

TECHNICAL CODES AND STANDARDS

Readers do not need to be knowledgeable about the details of building construction. Technical jargon and formalized technical specification have been avoided. The use of some technical terms has been considered desirable and their definitions are given in the Glossary at the end of the book.

In describing some materials, reference to British Standard Specifications has been unavoidable because they are the descriptions used by building materials suppliers.

At the time of writing, some of the relevant British Standards (BSs) relating to materials are in the process of being withdrawn and replaced by European Standards (ENs), others are about to be similarly superseded. All ENs related to matters quoted in this book are expected to be adopted prior to its publication. Nevertheless, because there will be a period of about two years during which reference may be made to either BS or EN terminology, both references are included in this book. This will also allow comparison with other guidance that may not include reference to the EN terminology.

METRIC AND IMPERIAL DIMENSIONS

Since the 1970s, the construction industry in the UK has been using the metric system exclusively for dimensions, weight and volume. However, many people outside the industry are more familiar with imperial measurements and have little ‘feel’ for metric dimensions. Because this book is for general readers, both metric dimensions and their imperial equivalents are given for general descriptions and some details of construction. For materials and their specification only the metric system is used to avoid the possibility of confusion and inaccuracy.

BUILDING REGULATIONS AND PLANNING CONTROL

Brickwork may be applied to many projects associated with houses and gardens. Some will be of a scale and type that, in the UK, might require official sanction in connection with the Town and Country Planning Acts and Building Regulations. Some projects that are quite large do not require planning permission because they fall within the category of permitted development. Rules for this are subject to change and if projected work affects the exterior of a building, particularly at the front, it is sensible to make an informal check with the Local Authority Planning Department.

Special conditions apply to work on buildings within Conservation Areas and to buildings that are ‘listed’ as being of special historic or architectural importance. The Local Authority Planning Department will be able to offer advice on these matters too.

Independent of planning controls, work on buildings must be in accordance with Building Regulations. The Local Authority Building Inspector will advise if a formal application for Building Regulations Approval is needed.

Boundary walls and fences require Planning Permission if they exceed a height of 1m (3ft 3in) adjacent to any public highway or right of way, or 2m (6ft 6in) on boundaries with other properties.

Garden structures are not subject to Building Regulations but, for safety reasons, it is very important that freestanding and earth-retaining walls are properly designed and built. Chapter 4 refers to authoritative published guidance, which will be appropriate in many cases, alternatively seek the assistance of a structural engineer.

BRIEF HISTORICAL BACKGROUND

Brick is man’s oldest manufactured building material. In world terms it is over ten thousand years old. The ancient civilizations in Mesopotamia and Egypt were prolific users of sun-dried clay (adobe) bricks for their buildings, not only for modest dwellings but also for their huge ziggurats and pyramids. They also fired clay bricks to make them stronger and more durable for use in the construction of river walls and hydraulic works. The Bible records that the Tower of Babel was built of burnt clay bricks, as were the walls of the city of Babylon. Both adobe and fired bricks were used in the worlds oldest town, Jericho, dating from the tenth millennium BC. Inexpensive, vermin-proof fireproof, and with excellent insulating properties, adobe bricks are still used today in regions with a dry climate. Countless millions are used in Africa, the Middle East, Asia and Central and South America.

Making sun-dried bricks in Nigeria.

In making fired clay bricks, the burning process transforms the natural clay into an inert, semi-vitrified material that will no longer revert to a mud-like state when soaked in water. Fired bricks are more durable than sun-dried ones and, therefore, more versatile in service.

The Romans first introduced brickmaking and brick masonry to Britain. Brick was a principal building material in the Roman Empire and their Legions set up brick and tile factories throughout their colonies. Although Roman buildings were often faced with elegant stone or marble, or with finely finished sand and lime plaster, the structure was frequently of brick masonry. Alternatively the structure was of stone rubble with brick used for bonding courses to provide stability and for the more regularized parts of the construction like quoins and the surrounds and arches to window and door openings.

The Roman Legions withdrew from Britain in AD412 and subsequently all but a very few of their buildings fell into ruin. Interestingly, their bricks have survived long after their buildings and they can be seen reused, centuries later, in Anglo-Saxon and Norman buildings.

Roman bricks in house at Herculanium.

Burgh Castle, Norfolk – bricks as bonding courses in Roman fortified walls.

Holy Trinity Church, Colchester – reused Roman bricks.

St Albans Cathedral, Hertfordshire – reused Roman bricks.

For example, in Colchester, Essex, the Church of the Holy Trinity has an Anglo-Saxon tower of rough stone with a large quantity of reused Roman bricks to bond them. The quoins and door and window openings are formed exclusively from Roman bricks. In Hertfordshire, the bricks in the transepts and crossing tower of St Albans Cathedral were taken from the ruins of the nearby Roman town of Verulamium and used by Norman builders in the twelfth century – nearly a thousand years after they were made and first used.

Roman bricks are of different sizes and proportions to medieval and modern ones. They are large, generally square and thin.

A Roman brick, Ephesus.

Following the fall of the Roman Empire, brick-making disappeared in most of Europe. In the medieval period, it spread slowly north again from Italy and Byzantium, where the technology had been kept alive. Regions where good building stone was scarce were generally rich in clay deposits and therefore the reintroduction of brickmaking was very expedient. Strong trading links between northern Europe and the eastern counties of England saw the technology reintroduced into Britain in the thirteenth and fourteenth centuries.

These medieval bricks are of very different proportions to the Roman ones. They are small, oblong blocks, easy to lift in one hand and, with a trowel of mortar in the other, lay to form brickwork. They are sized so that they bond together, overlapping regularly, without having to be cut to fit – so their size and proportions are eminently practical.

Tattershall Castle, Lincolnshire.

Immeasurable quantities of bricks like these were used over the next centuries but, initially in England, the new brick was a very prestigious material. It was also expensive and its early use is seen in grand houses, medieval castle-like buildings, built by the rich and influential of the mid-fifteenth century. Tattershall Castle in Lincolnshire, Herstmonceaux Castle in Sussex and Faulkbourne Hall in Essex are excellent examples.

At first bricks were handmade by itinerant brick-makers, generally setting up brickmaking on the building site to produce bricks for that building only. But brick was quickly accepted as an attractive, durable and versatile building material. It passed from being a select material for the privileged few, to become a staple of British building, and as such it was to grow in popularity over the next centuries.

Until about 1800, all bricks were handmade; not only was the clay placed in moulds by hand, but all the other activities of making involved manpower.

Faulkbourne Hall, Essex.

Handmaking a brick.

An extrusion machine.

Digging the raw material, barrowing it from the clay pit, preparing and mixing it with water for moulding, setting bricks in and drawing them from kilns were all done by hand, because no suitable machinery existed. In the nineteenth century two significant changes to brickmaking occurred simultaneously – the development of machinery and the discovery of new raw materials.

With the general development of industrialization in the nineteenth century, mechanization was applied to brickmaking. Machinery was introduced for preparing the clay and for forming bricks by moulding, pressing and extrusion. Improvements in kiln design and later the development of continuously burning multi-chamber and tunnel kilns, increased efficiency as did the use of coal, coke breeze and oil as fuels.

Prior to this period, only the shallow lying deposits of alluvial clays and brick earths were accessible for brickmaking, but in the nineteenth century mining for coal and other minerals led to the discovery of different types of clay. Dense shales and fireclays, found in association with coal measures and rock-like marls, proved to be excellent raw materials for brick. They required heavy machinery to pulverize, grind and mix them into a plastic consistency for forming into bricks.

A multi-chamber Hoffman kiln.

Typical Victorian terraced-housing in North London.

A modern house in North Oxford.

The nineteenth century saw the expansion of brickmaking into a highly developed industrial activity, stimulated by a huge demand for its products by the burgeoning economy of Victorian Britain. Popular demand for bricks and development of brick production processes continued throughout the twentieth century and into the twenty-first.

It is significant that no single production technique has been adopted to the exclusion of alternatives. The diversity of clay materials used, and the different techniques for forming bricks and firing them, give rise to differences in appearance and physical properties that are admired and desired. To maintain great variety, many of the techniques associated with early brickmaking, and its intermediate development, still persist within the modern industry. Today Britain is unique in having an industry that manufactures an exceptionally varied range of clay bricks.

TRADITIONAL BRITISH REGIONAL CHARACTERISTICS

In pre-nineteenth century Britain, before the development of canals and railways, road transport was dependent on the horse and cart, and haulage of heavy goods was expensive. As a result, when new building work required large quantities of bricks, and suitable clay was available, brickworks were frequently set up alongside to make the bricks. This procedure was continued throughout the nineteenth century for some of the huge civil engineering structures such as the tunnels, retaining walls, bridges, viaducts and similar structures associated with the canal and railway systems.

Modern bricks are produced in great variety of types.

Permanent brickworks were established to supply building needs, but bricks tended to be used within a limited area around the site of their production. Records show that, typically, the cost of bricks doubled if delivery distance increased from five miles to ten.

The characteristic appearance of older brick buildings often varies from region to region because of the colour, texture and physical properties of the different bricks available in each location. For example, the gault clays of Cambridgeshire gave rise to the prevalence of creamy, buff coloured bricks to be seen in the brickwork in that part of England. In contrast, the hard-edged, precise, smooth appearance of brickwork in the north of England is built of smooth, dense engineering bricks. These are made from local carboniferous shale clays by machine pressing or extrusion and wire-cutting. A deep red colour is typical, but restricting oxygen in the kiln (reduction firing) produces the blue colour that is characteristic of some of engineering bricks, e.g. Staffordshire blues.

Different again are the red bricks characteristic of south-east England. They are made from the iron oxide bearing weald-clay of Sussex and Kent. Traditionally they have been produced by handmaking, or by simple machine moulding, and have a rugged texture and a comparatively high water absorption. Variations in firing that occur in simple kilns and clamps, particularly when wood fired as was once common, give the multi-coloured appearance of southern counties stock bricks. Brickwork built with them tends to have a warm, rustic character.

Georgian London stock bricks in Clerkenwell.

As already noted, the building of the canal system in the early nineteenth century and the railway system later, were major users of brick. When in operation they became the providers of economic transport of bricks to the communities they served. For example, London’s St Pancras Station Hotel was built of bricks from Nottingham brought by the new railway. Similarly, the Liverpool Street Station complex was built with bricks from Lowestoft. There was a substantial and constant demand for bricks in London and countless millions of them were brought into the capital by railway, canal and river transport. The horse and cart, however, was still required for the transfer from railhead or quayside to building site, and this was not to change until the widespread introduction of steam traction engines and then petrol and diesel powered heavy lorries in the twentieth century.

London was unusual in being served from so far afield, but it did present an exceptional demand. The fletton brickmakers in the Northamptonshire and Bedford regarded London as there primary market. With works nearly ninety miles north of the metropolis they were quick to exploit cheap transport by rail. There was local brickmaking too, and in 1939 there were 367 brickworks in the Home Counties serving the Greater London area.

Gault bricks in nineteenth-century almshouses, Cambridge.

By the end of the nineteenth century brick was the staple building material in the British Isles, and towns in all but the most sparsely populated regions were served by brickworks. Up until the outbreak of the Second World War in 1939, the majority of bricks were used within thirty miles of where they were made.

The Second World War necessitated the closure of hundreds of brickworks and, with the return of peace, town and country planning controls and economic considerations precluded the re-establishment of a great number of them. The industry never reestablished the very high volume of production that characterized the latter half of the 1930s. There was a substantial demand for building materials to meet extensive repair and redevelopment programmes in the following decades, but brick and brick masonry were strongly challenged by ‘new’ materials and construction systems like concrete blocks, asbestos cement and metal sheeting, plywood, wood particle boards, glass and reinforced concrete and steel framed structures. Nevertheless, brick remained an important and popular material in British building and a directory of clay industries published in 1962 lists nearly 700 brick manufacturers, some having several individual works.

In the final decades of the twentieth century many brickworks closed, and amalgamation and acquisition of some of the old companies also occurred. By the end of the century the number of brick manufacturers has reduced considerably. A fall in demand for bricks because of reduced building programmes, economic recessions and changes in construction were obvious contributory factors, but planning restraints on clay extraction, demands of environmental legislation and escalating fuel costs were also important influences. Production capacity is still very high and variety very diverse, but a more rationalized brickmaking industry has emerged into the present century. The number of brick manufacturers in the British Isles is now less than one hundred. Many use one type of clay and one manufacturing technique, but there are a few very large organizations with several brickworks, so their product ranges include bricks made from a variety different clays and by different processes.

Staffordshire blue bricks in village school buildings, Warwickshire.

Sussex stock bricks in new house.

Although regional characteristics are apparent in the brickwork of many older buildings in Britain, the localized pattern of use, already eroded to some extent by the railway and canal transport, was profoundly changed by dramatic developments in road transport in the latter half of the twentieth century. Improvements in roads and the development of a comprehensive motorway network, coupled with the development of large capacity lorries equipped with self-unloading devices allow manufacturers to deliver bricks direct to a building site within hours.

For aesthetic reasons, new building is frequently required to use materials that match or are similar in character to locally existing ones. Even when there is no need to match, inevitably there will be personal preference of particular types of bricks. The brick industry is still able to provide its customers with an exceptional choice of bricks and clay pavers.

CHAPTER 2Brickwork Materials

BRICKS – VARIETY AND APPEARANCE

There is a very wide choice of clay bricks available. Manufacturing methods have developed over hundreds of years and today sections of the industry are highly mechanized and efficient. Nevertheless, some manufacturers still continue to use traditional methods in order to maintain certain favoured characteristics of their products. Clay is no longer dug by hand, forked-over and trod underfoot with water to work it into a mouldable state; such artless labour can be done much more effectively by machine. However, some bricks are still made by hand, one at a time in individual moulds, and some are fired in primitive clamps rather than in modern, computer-controlled, fuel-efficient kilns. The use of such traditional methods persists because they give unique texture and coloration to the products.

In contrast, other bricks are made very efficiently in huge quantities by highly developed, modern, machine methods and continuous firing kilns. These too have appearance characteristics derived from particularities of their production and the different types of clay used.

Because of differences of production and raw materials each brick product is unique. Some differences are obvious, others quite subtle. Between 1,200 and 1,500 different bricks are currently available in the British Isles. A range unequalled anywhere else in the world.

Depending on the type of clay, bricks are fired at temperatures between about 900°C and 1,200°C. Colours of clay bricks are generated by the reaction of the constituent minerals to the intense heat of firing.

Bricks in kiln showing fire marks and coloration.

The yellow, pink, orange, purple and black colours in the photograph above, are the result of variations in the firing ‘climate’. The clay is consistent, but minor differences in temperature and oxygen supply at the surfaces of each brick has affected the coloration – sometimes quite dramatically. As the bricks are taken out of the kiln they are sorted by colour into several groups that are marketed as different varieties.

Blue and red engineering bricks.

BASIC TERMINOLOGY

As might be expected from a technology hundreds of years old there are many terms to describe different types of bricks. Some are described in the Glossary. Others, although they once had specific meanings, have become obsolescent and have no formal standing in the context of modern building. Technical terms that are used in contemporary building specification and standards relate to significant aspects of quality, performance and usage, therefore it is important to understand their meaning.

Facing Bricks (or Facings)

Bricks of a consistent colour and texture, reasonably free from surface damage or blemishes, intended for building brickwork of consistent and attractive appearance. Most bricks on the market are facing bricks.

Handmade stock bricks – the curved crease marks should always ‘smile’ (not ‘frown’).

Common Bricks (or Commons)

Bricks without any guarantee of consistent surface appearance. They are intended for use in brickwork where consistent colour and texture is not of primary importance, e.g. backing walls, internal brickwork, foundations and brickwork that will be covered with cladding or some other applied finish.

Engineering Bricks (or Engineers)

Clay bricks that are particularly strong and dense, and conform to specific standard tests to measure their compressive strength and water absorption. Historically their primary use was in civil engineering construction, e.g. bridges, tunnels, quays and earth-retaining walls, but other types of bricks are sometimes used for such works. Similarly, engineering bricks are not limited to civil engineering work and are used for many types of building.

They are typically a strong red or a dark blue colour and smooth in texture. They are often specified for face work but, unless the manufacturer confirms otherwise, do not assume that an engineering brick will have the consistent appearance expected of a facing brick.

Stock Bricks (or Stocks)

This term was originally used to describe handmade bricks formed in a frame mould located on a workbench by a wooden ‘stock’, which forms the bottom of the mould. Such bricks are made with clay of soft mud consistency containing a proportion of ground fuel material to aid firing. Traditionally they would be fired in a ‘clamp’. Although such bricks are still produced, the term has now been extended to include machine and handmade bricks made from soft mud clays, not necessarily with fuel added or fired in clamps.

Handmade bricks usually have curved crease marks on the surface and this is a characteristic feature. Black spots are also common on multicoloured varieties; these are derived from particles of fuel added to the clay during its preparation to aid thorough burning of the brick during the firing process.

Stock bricks are typically, although not exclusively of high water absorption and of low or modest compressive strength. They often have excellent frost resistance.

The term ‘stock brick’ should not be confused with references made by merchants or brickyard staff to bricks that they have available, i.e. ‘in stock’.

Fletton Bricks

These are pressed clay bricks made from a unique clay that occurs in the East Midlands of England. It was originally found in the village of Fletton, near Peterborough, in 1881. It contains sufficient fuel to fire the bricks and consequently allows exceptional economy in production and very competitive pricing. Rail and road transport was a well-developed part of its marketing strategy and the fletton became an exceptionally popular brick type throughout Britain, especially for house construction and industrial building. Originally flettons were made as common bricks, but facing varieties were introduced in the 1920s by applying textures and sand to the surface of the bricks prior to firing. Fletton facing bricks are now available in a range of colours and textures.

Wirecut Bricks

These are a very familiar form of machine-made brick. Clay of stiff consistency is extruded through a rectangular steel die to form a length of clay with a width and thickness equivalent to the length and width of a brick. The strip is then cut into individual bricks by taut wires spaced equivalent to the height of a brick. To control the flow of the clay, rods are located in the throat of the extrusion machine, these produce perforations in the bricks. Straight from the extruder the clay has a smooth surface, but it may be textured in some way, e.g. with combs, cutters or rollers fitted to the exit from the die, or sand may be applied to give a granular texture.

Facing bricks – extruded wirecut and fletton bricks.

Multi Bricks (or Multi-Coloured)

A descriptive term meaning that the coloration of the brick varies across its surface and is not exactly replicated on every brick in a batch. Such bricks are intended to be laid randomly to produce an overall consistently blended appearance.

Multi-coloured stock bricks.

RECLAIMED BRICKS