Wood in Construction E-Book

Jim Coulson

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch
• Veröffentlichungsjahr: 2011

Seitenzahl: 409

Beschreibung

Wood in Construction - How to Avoid Costly Mistakes focuses on the basic principles and appropriate use of wood in construction and illustrates how to avoid or minimise problems, to ensure that wood performs as expected when used in a construction application. Based on the author's extensive experience of manufacturing processes and practical applications in the timber, construction, joinery, shop-fitting and furniture industries, Wood in Construction provides a guide to using wood in building in the real world. It describes the main causes of difficulty when using wood, and shows how to avoid or minimise problems, reducing the difficulties for the architect, engineer or specifier, builder and building owner. Technical enough to explain why things should be done in specific ways, but also practical enough to demonstrate how to use wood correctly and avoid doing the wrong things, this is an invaluable resource for construction specifiers (architects, engineers), carpenters, structural engineers, building surveyors, small/medium sized builders.

Leseprobe

Contents

Preface

1 Wood as a Material

1.1 Cellulose

1.2 Grain

1.3 Dimensional change in wood

1.4 Heartwood and sapwood

1.5 Natural durability

1.6 Rays

1.7 Radial and tangential directions

1.8 Permeability in timber

1.9 Chapter summary

2 More on Timber: Some Stuff About the UK Timber Trade

2.1 ‘Wood’ or ‘timber’?

2.2 Wood species and timber trading

2.3 Softwoods and hardwoods

2.4 Some more detail on cell structure

2.5 Trade names and scientific names

2.6 A cautionary tale about timber names

2.7 Growth rings

2.8 Earlywood and latewood

2.9 Rate of growth in softwoods

2.10 Rate of growth in hardwoods

2.11 Chapter summary

3 Water in Wood: Moisture Content and the Drying of Timber

3.1 The definition of moisture content

3.2 Moisture meters

3.3 ‘Wet’ or ‘dry’? In-service moisture contents and ‘EMC’

3.4 EMC

3.5 Specification of desired moisture content

3.6 Fibre saturation point

3.7 Shrinkage

3.8 Movement

3.9 Kiln drying

3.10 Air drying

3.11 Timescales for drying timber

3.12 Chapter summary

4 Specifying Timber – for Indoor or Outdoor Uses

4.1 British and European standards

4.2 Durability and treatability of different wood species

4.3 Use classes

4.4 Examples of timbers employed in different use classes

4.5 Hazard and risk – and their relative importance

4.6 Use Class 1 – examples

4.7 Use Class 2 – examples

4.8 Use Class 3 – examples

4.9 Use Class 4 – examples

4.10 Use Class 5 – examples

4.11 Chapter summary

5 The Quality of Timber: Grading for Appearance

5.1 The need for grading

5.2 ‘Quality’ or ‘grade’?

5.3 mQuality

5.4 Grade

5.5 The different types of grading

5.6 Appearance grading

5.7 Appearance grading: based on defects

5.8 Scandinavian grades

5.9 Unsorted, fifths and sixths

5.10 Russian softwood qualities

5.11 European appearance grading

5.12 North American softwood appearance grades

5.13 Clears, merchantable and commons

5.14 A comparison of Scandinavian grades and North American grades

5.15 Appearance grading: based on ‘cuttings’

5.16 The NHLA grades

5.17 FAS, selects and commons

5.18 Selects

5.19 ‘F1F’

5.20 Prime and Comsel grades

5.21 Malaysian grades

5.22 Prime, select and standard

5.23 ‘PHND’, ‘BHND’ or ‘sound’

5.24 Rules are made to be bent! (within reason)

5.25 Shipper’s usual

5.26 BS EN 942: the quality of timber in joinery

5.27 J classes

5.28 ‘Exposed face’

5.29 Chapter summary

6 Strength Grading and Strength Classes of Timber

6.1 Appearance versus strength

6.2 Visual strength grades

6.3 GS and SS strength grades

6.4 Strength classes for softwoods

6.5 BS EN 1912

6.6 SC3, SC4: C16 and C24

6.7 Machine grading

6.8 Other strength grades: Europe and North America

6.9 Select structural, No. 1 and No. 2 structural and stud grades

6.10 TR26

6.11 Specifying the strength class or the wood species: some things to think about

6.12 Hardwood strength grades

6.13 Tropical hardwoods

6.14 Temperate hardwoods

6.15 The ‘Size effect’

6.16 Hardwood strength classes

6.17 The marking of strength graded timber

6.18 Chapter summary

7 Wood Preservatives and Wood Finishes

7.1 Treat the timber last!

7.2 Wood preservative types

7.3 ‘Old’ and ‘new’ types of treatments

7.4 The basic methods of timber treatment

7.5 Low pressure treatment

7.6 High pressure treatment

7.7 Preservative chemicals

7.8 CCA preservatives

7.9 The ‘environmentally-friendly’ preservatives

7.10 ‘Tanalised’ timber

7.11 Organic compounds

7.12 ‘Treated’ timber

7.13 ‘Wood finishes’

7.14 Wood in exterior uses

7.15 Exterior finishes

7.16 Varnish – and paint

7.17 ‘Microporous’ exterior stains and paints

7.18 Non-film-forming finishes

7.19 Exterior paints

7.20 The durability of exterior finishes

7.21 The effects of lighter or darker colours

7.22 Chapter summary

8 Principal Softwoods Used in the UK

8.1 European redwood (Pinus sylvestris)

8.2 European whitewood (mostly Picea abies)

8.3 Sitka spruce (Picea sitchensis)

8.4 Western hemlock (Tsuga heterophylla)

8.5 ‘Douglas fir’ (Pseudotsuga menziesii)

8.6 Larch (mainly Larix decidua and L. kaempferi/L. leptolepis)

8.7 ‘Western red cedar’ (Thuja plicata)

8.8 Southern pine (Pinus spp – principally Pinus elliottii and P. palustris)

8.9 Yellow pine (Pinus strobus)

8.10 ‘Parana pine’ (Araucaria angustifolia)

8.11 Species groups

8.12 Spruce-pine-fir

8.13 Hem-fir

8.14 Douglas fir-larch

9 A Selection of Hardwoods Used in the UK

9.1 Ash, American (Fraxinus spp)

9.2 Ash, European (Fraxinus excelsior)

9.3 Beech, European (Fagus sylvatica)

9.4 Birch, European (mainly Betula pubescens)

9.5 Cherry, American (Prunus serotina)

9.6 Chestnut, Sweet (Castanea sativa)

9.7 Ekki (Lophira alata)

9.8 Greenheart (Ocotea rodiaei)

9.9 Idigbo (Terminalia ivorensis)

9.10 Iroko (Milicia excelsa)

9.11 Keruing (Dipterocarpus spp.)

9.12 Mahogany, African (Khaya ivorensis and K. anthotheca)

9.13 Mahogany, American (Swietenia macrophylla)

9.14 Maple (Acer saccharum)

9.15 Meranti (Shorea spp.)

9.16 Oak, American red (principally Quercus rubra and Q. falcata)

9.17 Oak, American white (principally Quercus alba, Q. prinus, Q. lyrata and Q. michauxii)

9.18 Oak, European (mainly Quercus robur)

9.19 Obeche (Triplochiton scleroxylon)

9.20 Opepe (Nauclea diderrichii)

9.21 Sapele (Entandrophragma cylindricum)

9.22 Tatajuba (Bagassa guianensis)

9.23 Teak (Tectona grandis)

9.24 Utile (Entandrophragma utile)

9.25 Walnut, American (Juglans nigra)

9.26 Walnut, European (Juglans regia)

9.27 Whitewood, American, or Tulipwood (Liriodendron tulipifera)

10 Wood-based Sheet Materials

10.1 Plywood

10.2 The two fundamental properties of plywood

10.3 Basic types of plywood

10.4 Conifer plywoods

10.5 Temperate hardwood plywoods

10.6 Tropical hardwood plywoods

10.7 Plywood glue bond and ‘WBP’

10.8 Exterior

10.9 Adhesives used in plywood

10.10 BS 1088 marine plywood

10.11 Plywood face quality

10.12 Appearance grading of face veneers

10.13 Conifer plywood appearance grades

10.14 Temperate hardwood plywood appearance grades

10.15 Tropical hardwood plywood appearance grades

10.6 Particleboards and wood chipboard

10.17 Flaxboard and bagasse board

10.18 OSB

10.19 Fibreboards

10.20 Hardboard, medium board and softboard

10.21 MDF

10.22 Chapter summary

Appendix 1 A Glossary of Wood and Timber Terms Used in the Timber and Construction Industries

Appendix 2 A Select Bibliography of Some Useful Technical References About Wood

Appendix 3 Some Helpful Technical, Advisory and Trade Bodies Concerned with Timber

Index

This edition first published 2012 © 2012 by John Wiley & Sons, Ltd

Wiley-Blackwell is an imprint of John Wiley & Sons, formed by the merger of Wiley’s global Scientific, Technical and Medical business with Blackwell Publishing.

Registered OfficeJohn Wiley & Sons, Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK

Editorial Offices9600 Garsington Road, Oxford, OX4 2DQ, UKThe Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK2121 State Avenue, Ames, Iowa 50014-8300, USA

For details of our global editorial offices, for customer services and for information about how to apply for permission to reuse the copyright material in this book please see our website at www.wiley.com/wiley-blackwell.

The right of the author to be identified as the author of this work has been asserted in accordance with the UK Copyright, Designs and Patents Act 1988.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher.

Designations used by companies to distinguish their products are often claimed as trademarks. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. It is sold on the understanding that the publisher is not engaged in rendering professional services. If professional advice or other expert assistance is required, the services of a competent professional should be sought.

Library of Congress Cataloging-in-Publication Data

Coulson, Jim (James C.)Wood in construction / Jim Coulson.p. cm.Includes bibliographical references and index.

ISBN 978-0-470-65777-5 (pbk. : alk. paper)1. Building, Wooden. 2. Building, Wooden–Great Britain. 3. Timber. 4. Timber–Great Britain. 5. Wood–Preservation. 6. Wood–Preservation–Great Britain. I. Title.TA419.C68 2012694–dc23

2011035190

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

Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic books.

Preface

This is not really a ‘text book’ in the proper, academic sense of those words. Think of it more as a sort of helpful guide to wood and all its uses in construction. Of course, if you want to learn some more about the highly interesting and rather more technical subject of ‘Wood Science’ (which of course, is a perfectly laudable ambition), then there are many other far more academically-oriented books out there that you can get your teeth into. And if you look at the back of this book, you’ll see I’ve given you a few helpful suggestions, along with the contact details of a number of technical, advisory or Trade bodies who can give you specific guidance on particular aspects of the uses of timber and wood-based products.

But, although this book is not meant to be highly erudite in the truly ‘scientific sense’, it is very definitely meant to be highly informative: so it will still tell you some legitimate and very useful facts about the best way to use wood, so as to get the best out of it. This book can, of course, be read by anyone with a positive interest in wood – be they an amateur or a hobbyist – but I have first and foremost aimed it the professional level: at the timber specifier or user. Nevertheless, it is my hope that even a serious amateur should get a lot out of it as well; because it is intended to try to put right a good many of the things that seem to go wrong with wood: and which are most often born out of a level of sheer ignorance about the material.

From my considerable experience, which has been gained throughout my very long and varied professional life, I have found that whenever things go wrong – such as in carpentry or joinery matters – it is never the fault of the wood. What has actually happened in reality is that someone, somewhere along the chain of specification, order, supply, installation and use, has done something that they really should not have done: and most likely, that was because they simply didn’t know any better. And that ignorance about even the very basics of wood is the knowledge gap which this modest little book is designed to fill.

At the time of writing, I have been a consultant Wood Scientist and Timber Technologist for something over 35 years. And in that period, I have been involved with a great many highly interesting projects: all of them connected with the myriad applications of wood; and the majority of those concerned with its uses in construction. I have climbed up to the top of countless Cathedral and Church towers; I have crawled beneath the floors of numerous Nonconformist chapels (and a lot of other very old structures); and I have clambered amongst the roof timbers of many, many buildings, both historic and newly completed. Shakespeare’s Globe Theatre and HMS Warrior were two of the more interesting projects needing some technical input from me; but amongst my hundreds of rather more mundane consultancy jobs, I have examined such things as kitchens in Kettering, decking in Doncaster, cladding in Cleckheaton and scaffold boards in Scunthorpe. I have inspected, selected, graded and rejected hundreds of thousands of boards, battens and planks of timber – both Softwoods and Hardwoods – in sawmills and woodyards as far afield as Montreal and Munich, Hull and Helsinki, Newcastle and New Zealand.

For many years, I was a Visiting Lecturer on Timber to both the Schools of Architecture and Engineering at the Universities of Newcastle and Durham. I have also delivered lectures in other parts of the world: such as on multi-storey timber frame construction at the University of Melbourne in Australia, and on wood preservation at the Centre for Advanced Wood Processing at the University of British Columbia in Vancouver. In fact in my time, I have carried out consultancy work on timber and wood-based panel products in over 30 different countries around the world. And I have also acted as an Expert Witness in hundreds of legal cases, large and small, where the only completely innocent party was the wood. The disputing parties were usually arguing the toss about poor specification, poor workmanship, or just plain ignorance of timber: any or all of which factors had then led to quite unnecessary losses in terms of money, time or materials.

Because Mankind uses wood the world over; but more especially, because the UK imports so many types of timber and wood products from every conceivable corner of the world, there is a huge amount of wood that is used in the UK, which never grew here. But it still needs care and thought in its use: and from the amount of time that I’ve spent teaching, investigating and explaining about wood to countless timber traders, builders, architects and engineers, I reckon to have a pretty good knowledge of wood in all its various guises. I understand intimately its cell structure and its properties; I know in detail about its types and species; and I am more than familiar with its grades and qualities. I understand almost intuitively how it works: and I am sure that I know how to make it work better, for everyone who wants to try and use it more thoughtfully.

But more than that: I have seen – far, far too many times – what people do wrongly with wood, which then makes this highly adaptable material perform badly, when it should work brilliantly.

As I hinted earlier, this book is intended to change all of the (often unintentional) bad behaviour on behalf of those who specify and use wood: by giving you, the reader, a basic – but I hope, very clear and workable – understanding of this unique and wonderful material. This book will arm you with the knowledge and information you need in a readily understandable form: thus helping you to get it right in any job you do with wood or wood-based products. Whether you are an architect, an engineer, a builder, a shopfitter, a timber salesman or simply an enthusiastic DIY-er: after you have read this book, I am confident that you will see wood in a whole new light, and that you will understand it a whole lot better than you did before. Furthermore, I am absolutely positive that, whatever your previous experience, you will learn something new from this book that will help you to use wood better and thus to get the best possible performance out of it. I hope you enjoy the journey you are about to embark upon. But most of all, I hope that in the future, you will use wood with care and understanding. Because it deserves it.

Oh: just before I leave you to get on with reading the book; let me give you a word or two of advice. The first couple of chapters – despite what I said right at the beginning of the introduction about the relative simplicity of this book’s contents – might seem to be a bit too ‘Wood Science-y’ for your taste: but please try to resist any temptation to skip them. The information that I’ve included for you in those early stages is meant to establish some essential ‘building blocks’ of wood knowledge that you really ought to keep in your head, as an absolute minimum; and which will help you to better understand the more practical stuff that comes up in the later chapters.

So please give the earlier, harder bit a go: you might even surprise yourself as to how interesting it actually is! And if you feel that you really can’t slog through all the technical details, then I suggest that you go straight to the Summary at the end of each chapter – so at least you can check up on the absolutely vital bits. But if you don’t even want to do that, then you’ll only have yourself to blame when the next court case goes against you, and you’re then faced with a very large bill. Which will very likely happen, sooner or later.

Acknowledgements

I must just add a word or two of thanks to a few people who have helped me with the preparation of this book. I owe a very large debt to Gervais Sawyer, who helped tremendously with preparing many of the photographs. Also, I would like to thank my son, Neil Coulson, for converting all of the coloured pictures to high definition Black & White, as required by the publishers. My thanks also go to Iain Thew of TFT Woodexperts for preparing most of the Tables; and finally, I must thank all those who have contributed particular photographs, and who have also generously allowed me to use their copyright within this book: BSW Timber plc, Osmose Ltd, Canada Wood UK, Bob Caille, and Simon Cragg.

Jim CoulsonBedale, North Yorkshire, March 2011

1

Wood as a Material

The very first thing to get absolutely clear at the start, is that there is no such thing as ‘wood’! Of course, there is the stuff that grows on trees (or rather, the stuff that grows inside trees): but what I mean to say here, is that there is not one individual, unique and single substance that can simply be referred to just as ‘wood’. There is no one, unique material that will do every single job without any problems and with no prior thought, no matter what you might require it to do for you.

The stuff that we know as ‘wood’ – and as most laymen are apt to use that term – is merely a catch-all word that covers a whole range of possibilities in terms of appearance and abilities. From the hard-wearing to the hardly worth bothering with: or from the very strong and durable to the very weak and rottable. So, in this book, I aim to show that any given species of wood is very different in its properties – and therefore in its usefulness – to some other vaguely similar sort of wood, but which happens to be of a different species.