Goss's Roofing Ready Reckoner

C.N. Mindham BSc has had a wide experience in the construction industry. After working at TRADA as Eastern Regional Officer, he developed a timber engineering business to become one of the country’s largest producers of trussed rafters. He has subsequently run his own consultancy and been Managing Director of companies manufacturing trussed rafters, joinery and prefabricated timber buildings, and architectural metal work.

1 Introduction and acknowledgements 1

Acknowledgements 2

2 Roofing terminology 3

3 Calculating the size of timber members 9

Strength and section size calculations 11

How do we calculate the loading on the roof? 11

Timber member sizing design: an example 12

Cost consideration 19

4 Calculating the length and cutting angles of timber members: data tables 5 ◦ –75 ◦ 20

The pitch 23

Using the tables to cut a common rafter 23

Hip jack rafters 28

Hip rafters 30

Valley jack rafters 32

The ridge 32

Purlins 34

5 Wall plates – strapping and gable strapping 109

6 Wind bracing and openings for dormers and roof windows 111

Openings for dormers and roof windows 113

7 Roofing metalwork and fixings 119

Nails, bolts and screws 121

8 Engineered timber roofing components and prefabricated roofs 123

Trussed rafters 123

Spandrel panels 125

Crane-on roof assemblies – trussed rafters 127

Crane-on roofs – structural panels 128

Crane-on roof assemblies – structural insulated panels 128

Attic to room-in-the-roof conversion 130

9 Roof coverings – underlay, battens and tiles 134

Underlay 134

Battens 138

Insulation and ventilation 140

Choosing the roof covering 154

Building regulations – thermal performance 162

10 Roof coverings – building detail drawings 179

The new BS 5534:2014 179

Manufacturer’s specification 180

Hips, ridges, verges and valleys – traditional and new methods of construction 180

Roofing putties 187

Natural slates 189

Concrete interlocking tiles 192

Plain and peg tiles 193

Asphalt shingles 198

Metal tiles 201

Lead substitutes 202

11 Solar panels 205

Planning and roof suitability 205

Roof construction 206

Fixing the panels 207

Possible improved fixing 208

Variations on panel design 211

12 Sheds and outbuildings 212

Permitted development 212

Types of permitted building 212

Design 215

The structure 215

The mono-pitch roof 216

The dual-pitch roof 216

Roof coverings 218

Make your new building save money! 220

13 Tools and equipment 221

Obtaining information from the drawing 221

To cut the roof 222

Setting up the roof structure 222

Roof coverings 223

14 Health & safety considerations 224

Access to the roof 224

Basic principles 225

Restoration and renovation of existing roof structures 225

Newly constructed roofs 226

The roof covering 226

Conclusion 227

Bibliography 229

Index 243