Details

Loft Conversions

2. Aufl.

von: John Coutts
56,99 €
Verlag:	Wiley-Blackwell
Format:	EPUB
Veröffentl.:	21.12.2012
ISBN/EAN:	9781118400029
Sprache:	englisch
Anzahl Seiten:	288

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Beschreibungen

Titelbeschreibung

Pressure on space and changes in planning law mean that loft conversions are now at the forefront in the race to improve the performance of Britain's ageing housing stock. Since 1990, roof space conversions have increased UK housing capacity by more than 200 million square feet - a living area equivalent to a medium-sized city - without the loss of a single square foot of greenfield land. Loft Conversions is the definitive technical guide to the conversion of roof spaces in single family dwellings. It brings together a wealth of practical and regulatory guidance in a form that is easy to read and comprehensively illustrated. This fully revised and updated second edition is intended primarily for architects, builders, surveyors and others professionally involved in the process of loft conversion. The insights it provides are also invaluable to self-builders and to householders wishing to achieve a deeper understanding of what a loft conversion involves.

Inhaltsverzeichnis

Preface xiii Acknowledgements xiv 1 Planning and legal considerations 1 Permitted development 1 Permitted development law 1 Commentary on permitted development provisions – England 4 Permitted development restrictions 10 Curtilage: raising party walls 10 Conservation areas 10 Article IV directions 11 Planning conditions affecting permitted development 11 Listed buildings 11 Other conditions affecting development 12 Restrictive covenants 12 Mortgage lenders 12 Buildings and contents insurance 12 Tree preservation orders 12 Bats 12 Lawful Development Certificate 13 Planning permission 13 Planning applications 13 Sources of planning guidance 15 Supplementary planning guidance 16 Supplementary planning documents 16 Design guides 16 Design codes 16 Local Development Framework 16 Unitary Development Plan 16 The Party Wall etc. Act 1996 16 Procedure 17 Disputes 18 2 The Building Regulations and building control 19 The Building Act 1984 19 The Building Regulations 19 Approved Document guidance 20 Compliance guides 21 Relationship between the Building Regulations and the Approved Documents 21 Building control 21 Local authority building control 22 Full plans 22 Building notice 24 Notification and inspection of work 25 Resolving Building Regulations disputes 26 Electronic building control applications 28 Approved inspector building control 28 3 External forms 30 Primary influences on form 30 Planning considerations 30 Pitch, plan and headroom 31 Stair access 31 Shallow-pitched roofs 31 Existing roof type 31 Conversion forms 33 Roof space only conversion 33 Box dormer conversion 33 Front box dormer conversion 34 Hip-to-gable conversion 34 Side dormer conversion 35 Full-width dormer with masonry flanks 35 Mansard conversion 36 Lean-to conversion 38 Half dormer 38 Existing attic rooms 38 Galleries and platforms 39 Traditional dormer forms 39 Gabled dormer 40 Hipped dormer 40 Flat dormer (small) 40 Cat slide dormer 42 Recessed dormer 42 Eyebrow dormer 42 Arched dormer 42 Segmental dormer 42 Pedimented dormer 42 Canted bay dormer 43 Design considerations 43 Fenestration 43 Roof detail 43 Vertical cladding and roofing materials 44 Chimney positions 45 Drainage 45 4 Fire safety 47 Regulatory framework 47 Main changes to Approved Document B (2006) 47 Fire resistance: basic requirements 49 Warning and escape 50 Floor height rules 51 Storey and floor numbering rules 51 Fire safety: common configurations – floor not more than 4.5 m above lowest ground level 52 Means of warning 52 Means of escape 52 One floor more than 4.5 m above ground level 54 Means of warning 54 First floor fire resistance 54 New floor (conversion) 54 Escape windows 54 Means of escape 55 More than one floor over 4.5 m above ground level 59 Galleries 59 Elements and terminology 62 Access room 62 AFD 62 Air circulation systems 62 Alternative escape route 62 Automatic self-closing devices (self closers) 63 Balconies and flat roofs 63 Cavity barriers 63 Doors – glazing in final exit 63 Emergency egress (escape) windows and external doors 64 Escape route 64 Final exit 64 Fire curtains 65 Fire detection and fire alarm systems 65 Fire doors 67 Fire stopping and the protection of openings 67 Habitable room 69 Inner room 69 Inner inner room 69 Loft conversion 69 Modified 30-minute protection 69 Open plan layouts 70 Passenger lifts 71 Sprinkler systems 71 Storey exit 71 Storey height measurement 71 Fire safety in context 72 5 Conversion survey 73 Survey procedure 73 Outline of survey elements 74 Survey elements in detail 76 Age of the building 76 Headroom and floor-to-ceiling height 76 External relationships 77 Internal layout 77 Roof form 77 Roof structure 77 Roof condition 79 Walls 80 Foundations 82 Internal walls and partitions 83 Floor and ceiling structure 84 Strength of existing timber elements 85 Water tanks 85 Drainage and services 86 Chimneys 87 6 Beams and primary structure 88 Approved Document guidance 88 Beam position relative to existing structure 88 Beam characteristics 89 Common structural steel sections 89 Engineered timber beams 91 Fire resistance of beams 94 Beam bearings 94 Mild steel bearing plates 95 Padstones 96 Beam penetration 98 Beam splices 98 Flange and web plate splice 98 End plate beam splices 99 Splice box 99 Inline box 99 PFC bearing 100 Beam-to-beam connections 101 Bolted connections 101 Grade 4.6 bolts 103 Grade 8.8 ‘high-strength’ bolts 103 HSFG bolt assemblies 104 Toothed plate connectors 105 Timber to masonry connections 105 Tension straps 105 Expansion bolts 105 Chemical anchoring 107 Disproportionate collapse 107 7 Floor structure 109 Role of the conversion floor 109 Elements of loft conversion floor design 110 Room height in the conversion (headroom) 111 Methods of support for floors 111 Beam-supported floors 112 Wall-supported floors 115 Floor joist selection 117 Joist spacing 117 Timber supplies 118 Machined (regularised) joist sections 118 Holes and notches in joists 119 Binders 119 New floor joist/existing ceiling clearance 122 Strutting 122 Trimming 123 Lateral support by floors 125 Floor fire resistance 128 Conversion floor (fire and sound resistance) 128 Floor materials and fixing 129 Conditioning 130 Staggered joints 130 Moisture and sound resistance 130 Fixing 131 T&G floor panels 131 Timber floorboards 131 Stairs 131 Headroom 131 Landings 132 Stair configuration 132 Structural implications 136 Stair provision: practical aspects 136 8 Wall structure 138 External stud walls 138 Stud arrangement and spacing 138 Elements of stud wall construction 141 Terminology 141 Openings 146 Supporting structural steel in stud walls 146 Vertical cladding 146 Fire resistance of dormer stud walls 148 Masonry walls (external) 149 Hip-to-gable conversion 150 Safety considerations during construction 151 Lateral restraint of flank gable walls 151 Brick selection and size 151 Solid blockwork 153 Mortar and brickwork 154 Parapet walls in loft conversions 155 Integrating new and old 155 Chimney cowls 159 Compartment (party) walls 159 Internal partitions 160 Window and door safety 160 Windows 161 Juliet balconies and balustrades 161 Glazing requirements for doors 162 Cleaning 162 Replacement windows 162 9 Roof structure 163 Roof types 163 The cut roof (common to about 1950) 163 The TDA roof truss (common 1947–1980) 163 Trussed rafter roofs (1965 to present) 165 Cut roof: structural forms 165 Single roofs 165 Double roofs 166 Cut roof: structural elements 167 Purlin 167 Ridge and rafters 170 Wall plates 172 Ceiling joists and collars 172 Cut roof: common conversion alterations 172 Modification of the roof structure 172 Reasons to remove a purlin 174 Replacement support for purlins 174 Rafters 176 Trimming 176 Sizing and loading of rafters 183 Hip-to-gable conversion 183 Notches and holes 184 Lateral support for gables 184 Replacement roof coverings 185 Flat roof: basic structure 186 Flat roof – warm deck (unventilated) 188 Flat roof – cold deck (ventilated) 189 Flat roof – hybrid warm roof (unventilated) 189 Roof ventilation 189 Continuity of airflow around roof windows 191 Ventilation – possible exemptions from the requirement 191 Approved Document guidance 192 Attic trusses 192 10 Energy performance 195 Methods of compliance 195 The reference method (elemental approach) 195 Area-weighted U-value method (optional approach) 196 Whole dwelling calculation method (optional approach) 197 Walls and roofs – performance requirements 197 U-values for new thermal elements 198 U-values for retained thermal elements 198 Standards for replacement thermal elements in an existing dwelling 199 Standards for renovation of thermal elements 199 Energy conservation – practical approaches 200 Insulation materials 200 Fixing internal insulation 201 Airtightness 203 Thermal bridging 204 Insulation for wall and roof elements 204 Existing (retained) solid brick masonry walls 204 New solid brick masonry walls 205 New solid blockwork walls 205 Existing (retained) cavity masonry walls 206 New cavity masonry walls 207 New tile hung stud walls 208 Existing (retained) or new pitched roof 208 New flat warm roof 209 New flat cold deck 210 Windows and other openings 210 Area of windows 213 Risks associated with insulation 213 Surface condensation 213 Interstitial condensation – all elements 214 Spalling risk – masonry walls 214 Electric lighting 214 Practical implications 214 Heating and hot water systems 215 Providing information about energy efficiency 216 Loft insulation when a loft is not converted 216 Ventilation for occupants 216 Background ventilation 217 Purge (rapid) ventilation 217 Extract ventilation 218 Ventilation – practical measures 218 All rooms 218 Habitable room (with external wall) 219 Habitable room (with no external wall) 219 Bathroom (with external wall) 219 Bathroom (with no external wall) 219 WC (with external wall) 220 WC (with no external wall) 220 Providing information about ventilation 220 11 Lofts in context 221 Why convert? 221 Loft conversion statistics 222 Underlying trends 222 The nature of the housing stock 222 Practical sustainability 223 Renewable energy 223 Reducing solar gain 224 Green roofs 225 Water conservation 225 Reducing construction waste and re-using materials 226 Energy Performance Certificates (EPCs) and insulating to a higher standard 227 Towards zero carbon 228 The Zero Carbon Loft 229 Appendix A Specification 233 Appendix B The Building Regulations: appeals and determinations 239 Appendix C Planning and curtilage 249 Glossary 252 Bibliography and useful contacts 260 Index 264 A colour plate section falls between pages 162 and 163

Autorenportrait

About the author John Coutts was educated at the City of London School and Brasenose College, Oxford. An author and journalist, he has worked with the BBC and Reuters in the UK and Dow Jones in South East Asia. He writes extensively on construction matters and advises leading multinationals on communications strategies for major infrastructure projects.

Back cover copy

LOFT CONVERSIONS Second Edition JOHN COUTTS Pressure on space and changes in planning law mean that loft conversions are now at the forefront in the race to improve the performance of Britain's ageing housing stock. Since 1990, roof space conversions have increased UK housing capacity by more than 200 million square feet – a living area equivalent to a mediumsized city – without the loss of a single square foot of greenfield land. Loft Conversions is the definitive technical guide to the conversion of roof spaces in single family dwellings. It brings together a wealth of practical and regulatory guidance in a form that is easy to read and comprehensively illustrated. This fully-revised and updated second edition is intended primarily for architects, builders, surveyors and others professionally involved in the process of loft conversion. The insights it provides are also invaluable to self-builders and to householders wishing to achieve a deeper understanding of what a loft conversion involves.