- 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 tank outputs
- 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 and bed joint reinforcements
- 6.1.19 Handling materials
- 6.1.20 Protection of the works during construction
- 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 framed walls and floors
- 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, terraces and balconies
- 7.1.1 Compliance
- 7.1.2 Provision of information
- 7.1.3 Flat roof, terrace and balcony general design
- 7.1.4 Drainage
- 7.1.5 Flat roof, terrace and balcony structural design
- 7.1.6 Timber structure and deck
- 7.1.7 Concrete decks
- 7.1.8 Profiled self-supporting metal decks
- 7.1.9 Profiled self-supporting metal roofing
- 7.1.10 Thermal insulation and vapour control
- 7.1.11 Waterproofing layer and surface treatments
- 7.1.12 Green and biodiverse (brown roofs) – including roof gardens
- 7.1.13 Blue roofs
- 7.1.14 Raised Podium
- 7.1.15 Detailing of flat roofs
- 7.1.16 Accessible thresholds and upstands
- 7.1.17 Parapets and guarding to terraces and 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 in cold roofs
- 7.1 Flat roofs, terraces 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
5.4.7Waterproofing systems
The waterproofing shall be suitable for intended use and installed in accordance with the design. Items to be taken into account include:
- Type A waterproofing barriers
- Type B structure, integral
- Type C drained cavity
- ancillary components.
Appropriate sequencing of work will enable logical and timely construction of the waterproofing system and prevent unnecessary damage to completed elements of work. Installation should be undertaken in accordance with the design and the installation method statement detailing the sequence of works.
Type A waterproofing barrier
Type A systems generally accepted by NHBC when assessed in accordance with Technical Requirement R3 include:
- post applied membrane (hot or cold adhesive)
- liquid-applied membranes
- geosynthetic (bentonite) clay liners
- mastic asphalt to BS EN 12970
- cementitious systems
- pre-applied fully bonded systems
- proprietary systems or products assessed in accordance with Technical Requirement R3.
- who are suitably qualified or have been trained by the manufacturer or supplier, and
- who are fully aware of the design and the manufacturer’s recommendations for installation.
- protection board, or
- carefully placed backfill material.
- BS EN 1992-1-1
- BS EN 1992-3
- Chapter 3.1 ‘Concrete and its reinforcement’.
- in-situ concrete with or without admixtures and crack widths limited by design
- in-situ high-strength concrete with crack widths limited by design and post-construction crack injections
- precast concrete systems assessed in accordance with Technical Requirement R3.
- the Quality Scheme for Ready-Mixed Concrete (QSRMC), or
- the BSI Kitemark scheme.
- achieve the necessary robustness, durability and waterproofing
- be suitable for the environmental exposure and ground conditions.
- by suitably qualified operatives who are fully aware of the requirements for placing concrete and reinforcement and for installing ancillary components used in Type B systems
- in accordance with the design.
- concrete specification.
- the type of concrete.
- concrete strength.
- proportion of any admixture.
- proposals for limiting crack widths.
- consideration of temporary support to the formwork.
- type and position of reinforcement.
- the method of making good holes in the concrete formed for shutter bolts and tie bars.
- positioning of structural elements.
- appropriate tolerances for the line and level of structural elements.
- the ratio of admixture to concrete specified in the design should take account of the recommendations of the admixture supplier and requirements of the independent assessment
- the reinforcement should be used to control crack widths, which should be in accordance with the design, but not be greater than 0.3mm max. for flexural cracks and 0.2mm max. for cracks that pass through the section
- suitable quality management systems and quality audits should be used to record and monitor the batching of admixture. This is best achieved by using ready mixed concrete (see clause 3.1.5).
- independently assessed, in accordance with Technical Requirement R3
- assessed according to the intended use
- used strictly in accordance with the manufacturer’s recommendations and requirements of the independent assessment.
- high-strength concrete may be specified in order to achieve the necessary level of waterproofing, but post-construction crack injection may be required in order to deal with cracking induced by increased thermal and shrinkage strains
- the reinforcement should be used to control crack widths, which should be in accordance with the design, but not be greater than 0.2mm max. for both flexural cracks and for cracks that pass through the section
- a minimum section thickness of 250mm should be used in the design.
- who are suitably qualified or have been trained by the manufacturer or supplier
- who are fully aware of the design and the manufacturer’s recommendations for installation
- using the fixings recommended by the manufacturer.
- a primary pump
- a secondary pump with battery or generator backup
- a suitable audio or visual alarm that indicates pump failure.
Plain polyethylene sheet should not be used as a waterproofing system.
Only fully bonded systems assessed in accordance with Technical Requirement R3 for the specific purpose should be used internally.
Design at junctions and corners should account for proprietary components and be in accordance with the manufacturer’s recommendations. Waterproofing barriers should return at corners to prevent water tracking behind.
The substrate to which the Type A system is to be applied should be clean, free from debris and prepared in accordance with the manufacturer’s recommendations. Bonded sheet membranes should only be applied directly to masonry substrates that are smooth and have flush pointed joints.
Type A waterproofing should be installed in accordance with the manufacturer’s instructions by operatives:
Completed waterproofing should be protected by:
The manufacturer’s recommendations for climatic conditions at the time of installation should be followed.
Type B structure, integral construction, concrete and application
Structural design should be undertaken by an engineer in accordance with Technical Requirement R5. The design of in-situ Type B concrete systems should be in accordance with:
Type B systems acceptable to NHBC include:
Specialist advice should be sought where other Type B systems are specified. BS 8102 contains guidance for the use of Type B systems, including secant, contiguous and sheet piles.
Ready-mixed concrete should be of sufficient strength and durability, and from a supplier operating under a quality control system acceptable to NHBC such as:
Other suppliers may be accepted if they operate to a standard acceptable to NHBC.
The concrete mix should be agreed between the engineer and the waterproofing design specialist, and:
Type B waterproofing should be installed:
The line, level and position of formwork and reinforcement should be checked prior to concrete placement to ensure that it is in accordance with the design.
Penetrations from tie bars etc. should be made good in accordance with the design.
Where joints are formed in concrete, surfaces should be clean and free of excessive laitance. Hydrophilic strips should be protected from water before the joint is formed.
Quality management systems and quality audits should be used to record and monitor the placement of concrete on site. Monitoring records should be supplied to NHBC as requested.
Design details for reinforced concrete structures should include:
Joints between components, including day work joints, should be durable and made watertight with appropriate waterstops or hydrophilic strips. Kickers, generally cast as part of the slab, should be used to form the joint between floors and walls.
Concrete with admixtures
Where the design of in-situ concrete waterproofing includes admixtures:
Admixtures should be:
Concrete without admixtures
Where the design of in-situ concrete waterproofing does not include admixtures:
Type C drained cavity construction
Type C systems that include a cavity drain membrane which forms a waterproof barrier are acceptable to NHBC when assessed in accordance with Technical Requirement R3. Where a Type C system is formed using a drained masonry cavity wall, the guidance in BS 8102 should be considered.
Type C systems should be designed to include a drainage system that adequately disposes of water to a suitable outlet, either by gravity or through a sump and pump. The drainage channel, sump and pump should include appropriately located access points for servicing and maintenance. To prevent backflow, the drainage system should be fitted with a one-way valve.
Type C waterproofing should be installed in accordance with the manufacturer’s instructions by operatives:
Pump systems should operate automatically and include:
Ancillary components
Ancillary components should be assessed as part of the waterproofing system. Alternatively, an assessment of compatibility and satisfactory performance should be provided for materials and products that are interchangeable between different systems.