- Home
- 1 Welcome
- 2 Introduction
- 3 General
- 3.1 Concrete and its reinforcement
- 3.1.1 Compliance
- 3.1.2 Provision of information
- 3.1.3 Storage of materials
- 3.1.4 Site-mixed concrete
- 3.1.5 Ready-mixed concrete
- 3.1.6 Concrete specification
- 3.1.7 Admixtures
- 3.1.8 Special types of concrete
- 3.1.9 Design of reinforced concrete
- 3.1.10 Installation of reinforcement
- 3.1.11 Blinding concrete
- 3.1.12 Formwork
- 3.1.13 Before concreting
- 3.1.14 Casting
- 3.1.15 Curing
- 3.1.16 Testing
- 3.1.17 Glossary
- 3.2 Cold weather working
- 3.3 Timber preservation (natural solid timber)
- 3.1 Concrete and its reinforcement
- 4 Foundations
- 4.1 Land quality – managing ground conditions
- 4.1.1 Compliance
- 4.1.2 Initial Assessment – desk study (all sites)
- 4.1.3 Initial Assessment – walkover survey (all sites)
- 4.1.4 Initial Assessment – results
- 4.1.5 Basic Investigation (sites where hazards are not identified or suspected)
- 4.1.6 Detailed Investigation (sites where hazards are identified or suspected)
- 4.1.7 Managing the risks (sites where hazards are found)
- 4.1.8 Unforeseen hazards
- 4.1.9 Documentation and verification
- 4.1.10 Guidance for investigations
- 4.1.11 Further information
- 4.2 Building near trees
- 4.2.1 Compliance
- 4.2.2 Provision of information
- 4.2.3 Building near trees
- 4.2.4 The effects of trees on shrinkable soils
- 4.2.5 Foundations in all soil types
- 4.2.6 Excavation of foundations
- 4.2.7 Foundations in shrinkable soils
- 4.2.8 Design and construction of foundations in shrinkable soils
- 4.2.9 Foundation depths for specific conditions in shrinkable soils
- 4.2.10 Heave precautions
- 4.2.11 New drainage
- 4.2.12 Foundation depth charts
- 4.2.13 Foundation depth tables
- 4.2.14 Example
- 4.2.15 Further information
- 4.3 Strip and trench fill foundations
- 4.3.1 Compliance
- 4.3.2 Provision of information
- 4.3.3 Ground conditions
- 4.3.4 Hazardous ground
- 4.3.5 Setting out
- 4.3.6 Services and drainage
- 4.3.7 Safe transmission of loads
- 4.3.8 Sloping ground and stepped foundations
- 4.3.9 Excavations
- 4.3.10 Reinforcement
- 4.3.11 Concrete
- 4.3.12 Movement joints
- 4.3.13 Construction joints
- 4.4 Raft, pile, pier and beam foundations
- 4.4.1 Compliance
- 4.4.2 Provision of information
- 4.4.3 Site conditions
- 4.4.4 Hazardous ground
- 4.4.5 Services and drainage
- 4.4.6 Safe transmission of loads
- 4.4.7 Construction
- 4.4.8 Engineer checks
- 4.4.9 Compressible materials
- 4.4.10 Reinforcement
- 4.4.11 Concrete
- 4.4.12 Movement joints
- 4.4.13 Resistance to moisture
- 4.5 Vibratory ground improvement techniques
- 4.5.1 Compliance
- 4.5.2 Hazardous sites and ground hazards
- 4.5.3 Desk study and site investigation
- 4.5.4 Confirmation of suitability for treatment
- 4.5.5 Suitability of ground conditions
- 4.5.6 Compatibility of the ground, design and treatment
- 4.5.7 Acceptable methods
- 4.5.8 Materials for use as fill
- 4.5.9 Granular material
- 4.5.10 Sitework
- 4.5.11 Adjacent excavations
- 4.5.12 Verification of completed treatment
- 4.1 Land quality – managing ground conditions
- 5 Substructure, Ground Floors, Drainage and Basements
- 5.1 Substructure and ground-bearing floors
- 5.1.1 Compliance
- 5.1.2 Provision of information
- 5.1.3 Transfer of loads
- 5.1.4 Ground conditions
- 5.1.5 Services and drainage
- 5.1.6 Ground below fill
- 5.1.7 Fill below floors
- 5.1.8 Infill up to 600mm deep
- 5.1.9 Materials used for fill
- 5.1.10 Harmful or toxic materials
- 5.1.11 Regulatory solutions
- 5.1.12 Walls below the DPC
- 5.1.13 Durability
- 5.1.14 Mortar
- 5.1.15 Wall ties
- 5.1.16 Blinding
- 5.1.17 Ground floor slab and concrete
- 5.1.18 Laying the ground-bearing floor slab
- 5.1.19 Damp proof course
- 5.1.20 Damp proofing concrete floors
- 5.1.21 Thermal insulation
- 5.1.22 Installation of insulation
- 5.1.23 Further information
- 5.2 Suspended ground floors
- 5.2.1 Compliance
- 5.2.2 Provision of information
- 5.2.3 Contaminants
- 5.2.4 Proprietary systems
- 5.2.5 Transfer of loads: concrete floors
- 5.2.6 Reinforced concrete
- 5.2.7 Construction of suspended concrete ground floors
- 5.2.8 Transfer of loads: timber floors
- 5.2.9 Thermal insulation and cold bridging
- 5.2.10 Damp-proofing and ventilation
- 5.2.11 Floor finishes
- 5.2.12 Floor decking
- 5.3 Drainage below ground
- 5.3.1 Compliance
- 5.3.2 Provision of information
- 5.3.3 Preliminary work
- 5.3.4 Foul and surface water disposal
- 5.3.5 Drainage system performance
- 5.3.6 Ground water drainage
- 5.3.7 Design to avoid damage and blockages
- 5.3.8 Durability
- 5.3.9 Septic tanks and cesspools
- 5.3.10 Septic tanks
- 5.3.11 Surface water soakaways
- 5.3.12 Component requirements
- 5.3.13 Excavation
- 5.3.14 Protection of pipework
- 5.3.15 Laying pipework
- 5.3.16 Protection of work
- 5.3.17 Testing
- 5.4 Waterproofing of basements and other below ground structures
- 5.1 Substructure and ground-bearing floors
- 6 Superstructure (excluding roofs)
- 6.1 External masonry walls
- 6.1.1 Compliance
- 6.1.2 Provision of information
- 6.1.3 Structural design
- 6.1.4 Fire resistance
- 6.1.5 Acoustic resistance
- 6.1.6 Exposure
- 6.1.7 Thermal insulation
- 6.1.8 Concrete blocks
- 6.1.9 Bricks
- 6.1.10 Stone masonry
- 6.1.11 Construction of masonry walls
- 6.1.12 Lintels
- 6.1.13 Materials suitable for mortar
- 6.1.14 Mortar
- 6.1.15 Render
- 6.1.16 Cladding
- 6.1.17 DPCs and cavity trays
- 6.1.18 Wall ties
- 6.1.19 Handling materials
- 6.1.20 Cold weather working
- 6.2 External timber framed walls
- 6.2.1 Compliance
- 6.2.2 Provision of information
- 6.2.3 Design checking and certification
- 6.2.4 Load-bearing walls
- 6.2.5 Fixing the frame
- 6.2.6 Nails and staples
- 6.2.7 Sheathing
- 6.2.8 Differential movement
- 6.2.9 Fire resistance
- 6.2.10 Protection from moisture
- 6.2.11 Timber preservation
- 6.2.12 Vapour control layers
- 6.2.13 Breather membranes
- 6.2.14 Wall ties and fixings
- 6.2.15 Insulation
- 6.3 Internal walls
- 6.3.1 Compliance
- 6.3.2 Provision of information
- 6.3.3 Supporting load-bearing internal walls
- 6.3.4 Masonry walls
- 6.3.5 Load-bearing timber walls
- 6.3.6 Fire resistance
- 6.3.7 Sound insulation
- 6.3.8 Partitions: internal non load-bearing
- 6.3.9 Construction of timber partitions
- 6.3.10 Construction of steel framed partitions
- 6.3.11 Construction of proprietary systems
- 6.3.12 Plasterboard
- 6.3.13 Damp-proof courses
- 6.3.14 Components
- 6.4 Timber and concrete upper floors
- 6.4.1 Compliance
- 6.4.2 Provision of information
- 6.4.3 Upper floor design
- 6.4.4 Fire spread
- 6.4.5 Sound insulation
- 6.4.6 In-situ concrete floors and concreting
- 6.4.7 Precast concrete
- 6.4.8 Timber joist spans
- 6.4.9 Timber joists
- 6.4.10 Construction of timber floors
- 6.4.11 Joists supported by intermediate walls
- 6.4.12 Joists connected to steel
- 6.4.13 Joists into hangers
- 6.4.14 Timber joist and restraint strap
- 6.4.15 Strutting
- 6.4.16 Joists and openings
- 6.4.17 Multiple joists
- 6.4.18 Notching and drilling
- 6.4.19 Floor decking
- 6.4.20 Floating floors or floors between homes
- 6.5 Steelwork
- 6.6 Staircases
- 6.6.1 Compliance
- 6.6.2 Provision of information
- 6.6.3 Fire precautions
- 6.6.4 Lighting
- 6.6.5 Glazing
- 6.6.6 Structural design
- 6.6.7 Headroom and width
- 6.6.8 Design of steps
- 6.6.9 Landings
- 6.6.10 Guarding
- 6.6.11 Handrails
- 6.6.12 Staircases made from timber and wood-based products
- 6.6.13 Concrete staircases
- 6.6.14 Steel staircases
- 6.6.15 Proprietary staircase units
- 6.6.16 Protection
- 6.7 Doors, windows and glazing
- 6.8 Fireplaces, chimneys and flues
- 6.8.1 Compliance
- 6.8.2 Provision of information
- 6.8.3 Solid fuel – fireplaces and hearths
- 6.8.4 Solid fuel – combustion air
- 6.8.5 Solid fuel – flue pipes
- 6.8.6 Solid fuel – chimneys
- 6.8.7 Solid fuel – outlets and terminals
- 6.8.8 Gas – fireplaces and hearths
- 6.8.9 Gas – combustion air
- 6.8.10 Gas – flue pipes
- 6.8.11 Gas – chimneys
- 6.8.12 Gas – outlets and terminals
- 6.8.13 Oil – fireplaces and hearths
- 6.8.14 Oil – combustion air
- 6.8.15 Oil – flue pipes
- 6.8.16 Oil – chimneys
- 6.8.17 Oil – outlets and terminals
- 6.8.18 All – fireplaces and hearths
- 6.8.19 All – fireplace surrounds
- 6.8.20 All – flue pipes
- 6.8.21 All – flue liners
- 6.8.22 All – flues
- 6.8.23 All – chimneys
- 6.8.24 Masonry
- 6.8.25 Mortar
- 6.8.26 DPC
- 6.8.27 Flashings
- 6.8.28 Terminals
- 6.8.29 Flue testing
- 6.8.30 Further information
- 6.9 Curtain walling and cladding
- 6.9.1 Compliance
- 6.9.2 Provision of information
- 6.9.3 Certification
- 6.9.4 Loads
- 6.9.5 Support and fixings
- 6.9.6 Durability
- 6.9.7 Interfaces
- 6.9.8 Insulation
- 6.9.9 Damp proofing and vapour control
- 6.9.10 Installation and tolerances
- 6.9.11 Electrical continuity and earth bonding
- 6.9.12 Maintenance
- 6.9.13 Glazing, gaskets and sealants
- 6.9.14 Cavity barriers and firestops
- 6.9.15 Ventilation screens
- 6.9.16 Handling and storage
- 6.9.17 Curtain walling
- 6.9.18 Rainscreen cladding
- 6.9.19 Insulated render and brick slip cladding
- 6.10 Light steel framing
- 6.10.1 Compliance
- 6.10.2 Provision of information
- 6.10.3 Structural certification
- 6.10.4 Structural design of load-bearing floors and walls
- 6.10.5 Structural design of infill walls
- 6.10.6 Roofs
- 6.10.7 Steel and fixings
- 6.10.8 Detailing of steel joists
- 6.10.9 Restraint
- 6.10.10 Construction of load-bearing walls and external infill walls
- 6.10.11 Interfaces with staircases
- 6.10.12 Fixing floor decking and ceilings
- 6.10.13 Other design issues
- 6.10.14 Behaviour in relation to fire
- 6.10.15 Acoustic performance
- 6.10.16 Moisture control
- 6.10.17 Insulation
- 6.10.18 Vapour control layers
- 6.10.19 Breather membranes
- 6.10.20 Cladding, lining and sheathing boards
- 6.10.21 Wall ties
- 6.10.22 Services
- 6.10.23 Further information
- 6.11 Render
- 6.1 External masonry walls
- 7 Roofs
- 7.1 Flat roofs and balconies
- 7.1.1 Compliance
- 7.1.2 Provision of information
- 7.1.3 Flat roof and balcony design
- 7.1.4 Timber and timber decks
- 7.1.5 Profiled metal decks
- 7.1.6 Concrete decks
- 7.1.7 Thermal insulation and vapour control
- 7.1.8 Waterproofing and surface treatments
- 7.1.9 Green and proprietary roofs
- 7.1.10 Detailing of flat roofs
- 7.1.11 Accessible thresholds
- 7.1.12 Drainage
- 7.1.13 Guarding to balconies
- 7.2 Pitched roofs
- 7.2.1 Compliance
- 7.2.2 Provision of information
- 7.2.3 Design of pitched roofs
- 7.2.4 Protection of trusses
- 7.2.5 Durability
- 7.2.6 Wall plates
- 7.2.7 Joints and connections
- 7.2.8 Restraint
- 7.2.9 Bracing for trussed rafter roofs
- 7.2.10 Strutting for attic trusses and cut roofs that form a floor
- 7.2.11 Support for equipment
- 7.2.12 Access
- 7.2.13 Dormer construction
- 7.2.14 Underlay and sarking
- 7.2.15 Ventilation, vapour control and insulation
- 7.2.16 Firestopping and cavity barriers
- 7.2.17 Battens
- 7.2.18 Roof coverings
- 7.2.19 Fixing tiles and slates
- 7.2.20 Weathering details
- 7.2.21 Valleys and hidden gutters
- 7.2.22 Drainage
- 7.2.23 Fascias and trim
- 7.2.24 Spandrel panels
- 7.1 Flat roofs and balconies
- 8 Services
- 8.1 Internal services
- 8.1.1 Compliance
- 8.1.2 Provision of information
- 8.1.3 Water services and supply
- 8.1.4 Cold water storage
- 8.1.5 Hot water service
- 8.1.6 Soil and waste systems
- 8.1.7 Electrical services and installations
- 8.1.8 Gas service installations
- 8.1.9 Meters
- 8.1.10 Space heating systems
- 8.1.11 Installation
- 8.1.12 Extract ducts
- 8.1.13 Testing and commissioning
- 8.2 Low or zero carbon technologies
- 8.2.1 Compliance
- 8.2.2 Provision of information
- 8.2.3 Clean Air Act
- 8.2.4 System design
- 8.2.5 Access
- 8.2.6 Handling, storage and protection
- 8.2.7 Sequence of work
- 8.2.8 Location
- 8.2.9 Building integration
- 8.2.10 Fixing
- 8.2.11 Electrical installation requirements
- 8.2.12 Pipes, insulation and protection from cold
- 8.2.13 Ground collectors
- 8.2.14 Fuel storage
- 8.2.15 Safe discharge
- 8.2.16 Testing and commissioning
- 8.2.17 Handover requirements
- 8.2.18 Further information
- 8.3 Mechanical ventilation with heat recovery
- 8.1 Internal services
- 9 Finishes
- 9.1 A consistent approach to finishes
- 9.1.1 Compliance
- 9.1.2 External walls
- 9.1.3 Internal walls and ceilings
- 9.1.4 Doors and windows
- 9.1.5 Floors
- 9.1.6 Glazing
- 9.1.7 Ceramic, concrete, terrazzo and similar tile finishes
- 9.1.8 Fitted furniture
- 9.1.9 Joint sealants
- 9.1.10 Paint finishes
- 9.1.11 Sanitary ware
- 9.1.12 Other surfaces and components
- 9.1.13 Pitched roof coverings
- 9.1.14 Garages
- 9.1.15 External works
- 9.2 Wall and ceiling finishes
- 9.3 Floor finishes
- 9.4 Finishes and fitments
- 9.5 Painting and decorating
- 9.1 A consistent approach to finishes
- 10 External works
- 10.1 Garages
- 10.2 Drives, paths and landscaping
- 10.2.1 Compliance
- 10.2.2 Provision of information
- 10.2.3 Stability
- 10.2.4 Freestanding walls and retaining structures
- 10.2.5 Guarding and steps
- 10.2.6 Drives, paths and landscaping
- 10.2.7 Materials
- 10.2.8 Garden areas within 3m of the home
- 10.2.9 Garden areas
- 10.2.10 Timber decking
- 10.2.11 Landscaping
Pitched roofs
7.2.14Underlay and sarking
Underlay and sarking shall be provided to resist the passage of moisture.
Underlay and sarking should:
- be in accordance with the manufacturer’s recommendations
- take account of the type and fixing of the roof covering
- be used in accordance with relevant assessments.
- be provided to all tiled roofs
- where it is above rigid sarking (fully supported), be of low vapour resistance, i.e. less than 0.25MNs/g (where the underlay is highly vapour-resistant, increased ventilation to the roof space or between the underlay and sarking should be provided as necessary)
- where exposed at eaves level, be UV resistant or of type 5U felt or a proprietary eaves guard used (type 1F may be used for the remainder of the roof)
- be supported by a continuous fillet or proprietary eaves support tray to prevent sagging (which can form a water trap)
- be securely fixed
- at vertical laps, be fixed only over rafters, and at horizontal laps, be held in place by battens
- be cut neatly, fit tightly and not be torn, i.e. where pipes project through the underlay
- be dressed into the gutter and cut neatly to fit tightly around service penetrations
- where traditional mortar pointing is used to bed ridge tiles, extend over the ridge
- continue over hips to form a 150mm minimum lap parallel with the hip rafter
- at abutments, be supported and turned up by a minimum of 100mm
- be draped to allow water to drain behind the tiling battens.
In areas of severe exposure, a rigid sarking with underlay is recommended.
Table 6: Acceptable materials for use as underlay and sarking
| Material | Standard |
|---|---|
| Tongued and grooved or square-edged boarding | BS 1297 |
| Exterior grade plywood | BS EN 636 service class 3 |
| Chipboard (type P5) | BS EN 312 |
| OSB (type OSB3) | BS EN 300 |
| Felt | BS EN 13707 |
| Proprietary products | Technical Requirement R3 |
Underlay should:
Table 7: Horizontal laps for unsupported underlay
| Pitch | Minimum horizontal laps |
|---|---|
| Less than 15° | 225mm |
| 15-34° | 150mm |
| 35° and above | 100mm |
