- 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
6.2.4Load-bearing walls
Load-bearing timber framed walls shall be constructed to support and transfer loads to foundations safely and without undue movement. Issues to be taken into account include:
- timber elements
- joints between panels and other elements
- positioning of sole plates
- packing under sole plates
- fixing panels
- support of prefabricated chimneys.
Timber elements
Load-bearing timber framed walls should be in accordance with BS EN 1995-1-1, and take into account:
- wind loads
- roof loads
- floor loads.
- a suitable grade in accordance with BS EN 338 and BS EN 14081-1
- dry graded and marked in accordance with BS 4978
- I-studs assessed in accordance with Technical Requirement R3.
- a minimum width of 37mm
- a maximum spacing of 600mm, unless other adequate support is provided for wall boards and fixings.
- the opening does not affect the stud spacing, or
- supported loads are carried by a rim beam or perimeter joist.
- securely fixed together, and securely fixed to the floor and roof framing
- constructed to prevent buckling.
- occur over a stud
- not coincide with joints between panels.
- the substructure should be correctly set out to receive the timber frame
- the timber frame should be checked to ensure that it is erected accurately, both horizontally and vertically
- the load from the frame should be supported as intended in the design
- protection should be provided where ledges form moisture traps.
- permanent packing should be used for gaps less than 5mm
- grout and mortar should not be used for gaps less than 5mm
- hollow plastic packing with reduced bearing surfaces should not be used
- temporary spacers can remain in place provided they are durable and non-degradable.
- designed and approved by the timber frame designer to suit the horizontal and vertical loads on the sole plate
- at least the same plan area as the load points, e.g. studs or posts.
- fixings, including nailed joints and sheathing, should be as scheduled in the design
- they should be securely fixed together, to the floor and to the roof framing
- sole plates and head binders should be provided to bind the panels together.
Timber in external framed walls should be:
Individual timber studs should have:
Narrow or inaccessible gaps between studs which are difficult to insulate should be avoided.
Lintels and cripple studs should be provided at openings in load-bearing panels except where:
Sheathing and associated fixings should be structurally adequate, and resist racking due to wind and other forces.
Where masonry cladding is used, additional studs may be required at openings to fix wall ties.
Multiple studs should be included to support multiple joists and other point loads, unless otherwise specified by the designer. Where head binders are not provided, joists and roof trusses, including girder trusses and other similar loads, should bear directly over studs.
Joints between panels and other elements
Wall panels should be:
At joints between wall panels, sole plates and head binders should be provided to bind panels together. Joints in sole plates and head binders should:
Positioning of sole plates
When setting out:
Packing under sole plates
Where packing is required to ensure the timber frame or sole plate is level:
Permanent packing should be:
Packing exceeding 20mm should be agreed between the timber frame manufacturer’s engineer and NHBC. The following methods are generally acceptable to NHBC for packing up to 20mm.
Permanent structural packing under sole plate
The sole plate should be levelled on temporary spacers.
When the first lift construction (including wall panels, first floor structure, or roof structure in a single storey building) has been erected, permanent packing should be placed under the sole plate, which can be:
■ free-flowing non-shrinkable grout for the full length and width of the sole plate, or
■ individual packers placed under each load point, e.g. stud or post.
Bedding of the sole plate
The sole plate should be laid and levelled on a continuous bed of mortar prior to the erection of the wall panels.
The bedding should extend the full width of the sole plate. Care is needed to ensure that the bedding is not disturbed during the fixing of the sole plate.
Double sole plate 'sandwich'
The lower sole plate should be fixed to follow the contours of the supporting structure.
The upper sole plate should then be fixed on top and levelled with temporary spacers inserted between the sole plates.
When the first lift construction has been erected, permanent packing should be inserted under each load point, e.g. stud or post. As this method uses an additional sole plate, the extra shrinkage should be taken into account.
Fixing panels
The wall panels should be adequately fixed to the sole plate so the frame can resist both lateral and vertical forces.
When fixing panels:
Support of prefabricated chimneys
Prefabricated chimneys should be supported by the: