Builders

VertDivider

Technical Guidance

Foreword

To address some of the frequently asked questions of NHBC Standards and Technical we have developed the following Technical Guidance to amplify some of the detail contained in the NHBC Standards.

The Technical Guidance is referenced using the same format as the NHBC Standards.

I hope you will find this information a useful addition to the NHBC website and any feedback you may wish to provide, including new areas to be included, will be very welcome.

Kind Regards

Graham Perrior
Acting Group Head of Standards and Technical.

Disclaimer

Information contained within 'Technical Guidance' is for general purposes and guidance only and it is addressed to persons who are competent construction industry workers.  It contains only brief summaries of aspects of the subject matter and does not provide comprehensive statements of the relevant construction industry practice.  It does not constitute professional advice and does not provide a substitute for it.  All information relates to circumstances prevailing at the date of publication and will not be updated to reflect subsequent developments.

General

New home built alongside existing home
Japanese Knotweed (amended April 2011)
Conversions and renovations

NHBC Standards Chapter 4.2 Building near trees

Strip/trench fill foundations - slip membranes

NHBC Standards Chapter 4.4 Strip and trench fill foundations

Foundation concrete
Steps in foundations
Minimum foundation depths in clay soils

NHBC Standards Chapter 4.5 Raft, pile, pier and beam foundations

Raft foundations - edge detail

NHBC Standards Chapter 5.2 Suspended ground floors

In-situ concrete suspended ground floors
Precast concrete floor planks to ground floors
Radon protection - provision of sump
Ventilators in compartment walls beneath suspended ground floors (new issue March 2013)

NHBC Standards Chapter 5.3 Drainage below ground

Drainage - connections to pre-formed inspection chamber bases
Lightweight drainage covers
Access to manholes/inspection chambers
'Y' junctions in drains under buildings (amended March 2013)
Field drainage systems in septic tanks and small private sewerage treatment plants
Underground drainage - Pipe cross-overs (new April 2011)

NHBC Standards Chapter 6.1 External masonry walls

Partial fill insulation to gable walls (amended April 2011)
Small pediment gable walls
Corrosion protection to render beads
Dpc trays above soldier courses/stone heads
Dpc trays to rendered walls
Installation of lead flashings
Bedding lintels (amended April 2011)
Movement joints below dpc
Restraint straps to gable walls of garages (amended March 2013)
Damp proofing around meter boxes
Movement joints in clay brick masonry
Cavity trays to bay windows
Masonry bed joint reinforcement
Toothing of brickwork
Concrete fill in a cavity wall
Ducts/flues through core drilled holes
Block bonding
Movement joints in masonry
Lintels within coastal sites (new April 2011)
Lintels  to walls over drive-through access to houses (new April 2011)
Lintels over wide garage openings (new April 2011)
Wall ties at movement joints (new April 2011)
Face fixed restraint straps to gable walls in dwellings (new March 2013)

NHBC Standards Chapter 6.2 External timber framed walls

Socket outlets - fire barriers
Ventilation of cavities
External timber framed walls - movement gaps at eaves and verges
Rendering on timber framed walls

NHBC Standards Chapter 6.3 Internal walls

Firestopping to garage walls
Separating walls - cavity insulation
Dpcs under timber soleplates to internal partitions
Separating wall construction within roof spaces
Timber stud partitions
Sockets and switches in light steel framed separating walls

NHBC Standards Chapter 6.4 Timber and concrete upper floors

End support to chipboard flooring
Noggings for lateral restraint straps
Bolt fixing of multiple joists
Strutting to floor joists
Sealing around ends of engineering joists
Support of plasterboard
Support of joist hangers
Recessed light fittings in ceilings to intermediate floors in houses
Lateral restraint straps to beam and block and precast or prestressed intermediate floors

NHBC Standards Chapter 6.5 Steelwork support to upper floors and partitions

Steel beams - parallel connections
Perforated Padstones (new March 2013)

NHBC Standards Chapter 6.6 Staircases

Handrail to staircases - tapered treads/winders (amended March 2013)
Stair nosings
Guarding to treads and risers
Risers to private stairs - thick floor coverings
Nosings to stairs in common areas (new March 2013)

NHBC Standards Chapter 6.7 Doors, windows and glazing

Gaps around PVC-U windows
Door limitation devices
Background ventilation to utility rooms
Gaps around timber windows and timber door frames
Door between an integral garage and the dwelling - security
Egress windows and conservatories
Fire doors to bathrooms
Window restrictors and protection against falling 
View outside main entrance door (new April 2011)
Door Ironmongery - Students accommodation (new March 2013)
Door limitation devices (new March 2013)

NHBC Standards Chapter 6.8 Chimneys and flues

Installation of gas flue pipes in roof spaces
Guarding to gas flue terminals
Termination of horizontal flues

NHBC Standards Chapter 7.1 Flat roofs and balconies

Balcony drainage

NHBC Standards Chapter 7.2 Pitched roofs

Diagonal bracing to double hipped roof
Plasterboard fire-resisting ceiling in contact with single leaf masonry
Use of nail guns for fixing trussed rafter bracing
Wall plates - bedding, lengths and joints
Bedding verge tiles
Lateral restraint provided by gable ladders
Bracing of mono-pitch roof trusses
Pitched roofs - bedding verge undercloaks
Attic trusses - bracing
Pitched roofs to garages - holding down straps
Roofng underlay at eaves level
Ventilation of small roofs
Fixing valley trussed rafters (diminishing trussed rafters)
Canopy flashings
Diagonal bracing to trussed rafters
Fixing roof tiles in valleys
Loft hatches and fire resistance
Vapour permeable underlays (VPUs) and roof void ventilation
Fixing tiling battens using nail guns
Slate hook fixing (amended April 2011) 
Tiling battens (new April 2011)

NHBC Standards Chapter 8.1 Internal services

Discharge pipes from UVHWSS in garages
Earth bonding - certificate of compliance
Pipe insulation in airing cupboards
Earth bonding plastic plumbing
Use of flexible ducting to connect SVP
Insulation of heating pipes in timber floors
Electrical - earth bonding metal back boxes
Sound insulation of soil pipes in floor voids
Extract fans - air leakage
Plastic plumbing - pipe support
Plastic plumbing - insulation
Air Admittance Valves
Wiring to wall lights (amended April 2011)
Consumer unit - labelling (amended April 2011)
Metal splashbacks - earthing/bonding
Sound proofing to SVP's 
Fixing to cable trays (new April 2011)
Electrical fittings near cookers and sinks (new March 2013)
Consumer units - blanking pieces (new March 2013)
Tracer tapes to plastic water pipes (new March 2013)

NHBC Standards Chapter 8.2 Wall and ceiling finishes

Edges of ceramic tiling
Dry lining to walls with chemical dpcs
Dry lining walls with different types of masonry
Edge sealing to dry lining

NHBC Standards Chapter 8.3 Floor finishes

Fibre reinforced screeds

NHBC Standards Chapter 9.1 Garages

Garage - concrete floors
Garage wall construction
Compartment walls between garages
Carports - fire separation

NHBC Standards Chapter 9.2 Drives, paths and landscaping

Log retaining walls
Profles for access steps
Disabled access to principal entrances (England & Wales)
Pedestrian access
Guarding to retaining structures (amended March 2013)
External steps - mobility access (England & Wales only) (amended April 2011) (under review)
Retaining walls across gardens
Guarding to retaining structures in communal areas (new March 2013)
Handrails to steps in paths (new March 2013)