Content
Foreword xi
Preface xiii
Illustration acknowledgements xvi
Part 1: Nature of Wood 1
1 Origins and durability of building timber 3
1.1 Introduction 3
1.2 Structural polymers 3
1.3 Cell wall 5
1.4 Structure of wood 7
1.4.1 Softwoods and hardwoods 7
1.4.2 Structure of softwoods 8
1.4.3 Structure of hardwoods 9
1.5 Functional tree: differences between softwood and hardwood species 9
1.5.1 Juvenile or core wood 13
1.5.2 Mature wood 14
1.5.3 Over-mature wood 15
2 Sorption of water by timber 16
2.1 Natural hygroscopicity 16
2.1.1 Ray cell orientation 17
2.1.2 Latewood/earlywood orientation 17
2.2 Age-related changes 17
2.3 Effects of decay on moisture sorption 19
Part 2: Agents of Decay and Traditional Treatments 21
3 Post-harvest changes and decay 23
3.1 Effects of moisture content 23
3.2 Nutrient availability after conversion: the potential for decay 24
3.3 Damage caused by insects 25
3.3.1 Cell-content feeders 27
3.3.2 Cell-content and partial cell-wall feeders 27
3.3.3 Cell-content and cell-wall feeders 27
3.4 Decay caused by fungi 27
3.4.1 Moulds and stains 28
3.4.2 Soft rot 28
3.4.3 White rot 29
3.4.4 Brown rots 29
3.5 European hazard classification for building timbers 30
3.6 Physical/chemical decay 31
3.6.1 Thermal damage 31
3.6.2 Visible and ultraviolet (UV) light 32
3.6.3 Surface degradation caused by mechanical damage 32
3.6.4 Chemical decay 32
3.7 Acidity and corrosion of metals by timber 35
4 Death watch beetle (Xestobium rufovillosum) 37
4.1 Brief history of the beetle and the development of insecticides 37
4.2 Biology of the death watch beetle 39
4.3 Monitoring current activity and population 48
4.4 Methods of treatment 49
4.4.1 Defrassing 50
4.4.2 Spraying 50
4.4.3 Injection 52
4.4.4 Paste treatment 53
4.4.5 Smoke treatment 53
4.4.6 Insect traps 54
5 Furniture beetle or woodworm (Anobium punctatum) 55
5.1 Brief history of the beetle and its treatment 55
5.2 Biology of the furniture beetle 58
5.3 Monitoring current activity and population 60
5.4 Methods of treatment and control 62
5.4.1 Spray and injection treatments 62
5.4.2 Fogging 63
5.4.3 Freezing/heating 64
5.4.4 Fumigation 64
6 Minor decay insects 65
6.1 House longhorn beetle 65
6.1.1 Methods of treatment 67
6.2 Powder post beetles (Lyctidae, Bostrychidae) 67
6.2.1 Methods of treatment 70
6.3 Weevils (Curculionidae) 70
6.3.1 Methods of treatment 71
6.4 Wharf borer (Nacerdes melanura) 71
6.4.1 Methods of treatment 72
6.5 Pinhole and shothole borers (Scolytidae, Platypodidae) 72
6.6 Risk of termites in Britain 73
6.6.1 Methods of treatment 75
7 Dry rot 76
7.1 History of dry rot and early treatments 76
7.2 Biology of dry rot 80
7.3 Traditional treatments 86
7.3.1 Exposing the full extent of the infection 86
7.3.2 Cutting back past the last signs of decay 87
7.3.3 Wall irrigation/toxic box treatments 87
7.3.4 Spray and paste treatments 88
7.3.5 Fungicidal renders 88
7.3.6 Heat treatments 89
7.3.7 Timber reinstatement 89
7.4 Detection of dry rot with dogs 89
8 Wet rots and minor decay fungi 90
8.1 Identification of fungi in buildings 90
8.2 Category A: Moulds 90
8.2.1 Damage to timber 90
8.3 Category B: Jelly fungi or plaster moulds 91
8.3.1 Elf cup fungi (mostly Pezizaceae) 92
8.3.2 Pyronema spp. (Pseudoascoboleae) 92
8.3.3 Damage to timber 92
8.4 Category C: Resupinate fungi 92
8.4.1 Cellar rot (Coniophora puteana) 92
8.4.2 Asterostroma cervicolor 93
8.4.3 Damage to timber 93
8.5 Category D: Pore fungi 93
8.5.1 Mine fungus (Antrodia vaillantii) 95
8.5.2 Oak rot (Donkioporia expansa) 95
8.5.3 Damage to timber 97
8.6 Category E: Gilled fungi 98
8.6.1 Ink cap fungus (Coprinus) 98
8.6.2 Damage to timber 98
8.7 The treatment of wet rots 98
9 Timber pretreatments 100
9.1 Brief history of pretreatments 100
9.2 Modem water-based preservatives for pressure impregnation 102
9.3 Organic solvent-based preservatives for pressure impregnation 103
9.4 Diffusion pretreatments 105
9.5 Dip/immersion pretreatments 105
9.6 Preservative penetration 106
9.7 Metal corrosion in pretreated timber 107
9.8 Selection and use of pretreated timber 107
9.9 Disposal of pretreated timber and waste 108
10 Regulations, legislation and charters 110
10.1 European Standards for wood preservation 110
10.2 Controls on the manufacture and use of pesticides 110
10.3 Protection of bats 111
10.4 Control of Substances Hazardous to Health (COSHH) Regulations 1994 113
10.5 Construction (Design and Management) Regulations (CDM) 1994 115
Part 3: Effects of the Building Environment on Timbers 117
11 Drying and wetting: A historical perspective on timber decay within buildings 119
11.1 Changes in moisture content after felling 119
11.2 Air drying 120
11.3 Kiln drying 121
11.4 Moisture, the key to decay 125
11.5 Air temperature and relative humidity 127
11.6 Water absorption along the grain 128
11.7 Water absorption across the grain 130
11.8 Some consequences of conversion 131
11.9 Timber replacement and re-use 133
11.10 From oak frames to brick and softwood 133
11.11 Some consequences of war 136
11.12 Durability of old and modern timbers compared 136
11.13 Use of second-hand timbers 139
11.14 Timber and walls 140
12 Fire damage and dereliction 142
12.1 Dry rot and fire damage 142
12.2 Weatherproofing 142
12.3 Removal of debris and timber cleaning 143
12.4 Stripping interiors 144
12.4.1 Position within the building 144
12.4.2 Floors, panelling, joinery and linings 147
12.4.3 Storage 148
12.4.4 History of dry rot 149
12.5 Progression of fungal assemblages 149
12.6 Dereliction 150
12.7 Modes and rates of drying 151
12.7.1 First-stage drying 152
12.7.2 Second-stage drying 152
12.8 Drying by increased ventilation 153
12.9 Accelerated drying 153
12.9.1 Air blowers 155
12.9.2 Dehumidifiers 155
12.10 Isolation of timbers and the mobilization of wall salts 157
13 Monitoring the building environment 160
13.1 Moisture meters and their accuracy in timber 160
13.1.1 Moisture monitoring by the oven/balance method 162
13.1.2 Remote moisture monitoring 163
13.2 Brickwork and masonry moisture monitoring 165
13.3 Automated remote monitoring 165
13.3.1 Environmental monitoring 166
13.3.2 Leak detection 166
13.3.3 Multiparameter moisture monitoring 166
Part 4: Evolving a Philosophy for Timber Treatment 169
14 Resolving conflicts between treatment and conservation 171
14.1 Remedial industry 171
14.2 Precautionary treatments 172
14.3 Guarantees 173
14.4 International and national policies on minimal intervention 174
14.5 Natural control of decay 176
14.5.1 Natural insect population regulators within the building ecosystem 176
14.5.2 Environmental control of death watch beetle: Westminster Hall 180
14.5.3 Environmental control of furniture beetle 184
14.5.4 Environmental control of dry rot 184
14.6 Holistic approach to dry rot treatment 187
14.6.1 Evaluate the cause and level of fungal activity 187
14.6.2 Evaluate moisture levels and distribution 187
14.6.3 Locate and assess all timbers at risk 187
14.7 Conclusions 187
Appendix A: Analytical approach to preservative treatment 189
A.1 Introduction to the use of analytical keys 189
A.2 Key to the treatment of death watch beetle 190
A.3 Key to the treatment of furniture beetle 192
A.4 Key to the treatment of decay caused by fungi, including dry rot 194
Appendix B: Dry rot case studies 197
B.1 Case study 1: Amiston House, Midlothian 197
B.2 Case study 2: Bute Hall, University of Glasgow 198
B.3 Case study 3: Walsworth Hall, Gloucestershire 199
B.4 Case study 4: Sea Captain's House and Calendering Works, Dundee 202
B.5 Case study 5: Lees Court, Kent 206
B.6 Case study 6: Christchurch, Waterloo, Merseyside 207
References and bibliography 210
Index 222