1.1 Introduction to the Standards and Technical Requirements
This Chapter introduces the Standards and gives the Technical Requirements.
NHBC Standards do not cover aspects of health and safety relating to building operations and to the handling and use of certain building materials. Such matters are covered by statutory requirements.
INTRODUCTION TO THE STANDARDS
APPLICATION OF THE STANDARDS
The NHBC Standards give the Technical Requirements, Performance Standards and Guidance for the design and construction of dwellings acceptable to NHBC. In the Standards, a DWELLING means a HOME as defined in the NHBC Rules.
The Standards come into effect for every NHBC registered home whose foundations are concreted on or after the 1 January 2011 and apply throughout the UK, unless otherwise stated.
COMPOSITION OF THE STANDARDS
The Standards are divided into 10 Parts, each covering a particular aspect. All parts may not currently contain chapters. The Parts follow the usual construction process; from design through to construction on site. NHBC Standards do not cover aspects of health and safety relating to building operations and to the handling and use of certain building materials. Such matters are covered by the statutory requirements.
In general, each Chapter is made up of sections dealing with Design, Materials and Sitework.
In this Chapter, the Technical Requirements, which MUST be met by the Builder, are in red.
Most of the Chapters consist of detailed Performance Standards in black, for each Design, Materials or Sitework section. Each section contains clauses which are prefixed by the Chapter number and D, M or S for Design, Materials or Sitework, respectively.
Alternative standards of performance will be acceptable ONLY if, in the opinion of NHBC, the Technical Requirements are met and the standard achieved is not lower than the stated Performance Standard.
If the Performance Standards are followed the Technical Requirements will be met.
Guidance on how the Performance Standard may be met is in light blue.
Diagrams may contain text in red. This is to highlight points and has no mandatory status.
Guidance is based on normal construction procedures and recommended practices which have been shown to be satisfactory and acceptable over time. NHBC will consider alternative methods to meet specific requirements, subject to prior consultation and evaluation.
LIMITATIONS ON USE
The Technical Requirements, Performance Standards and Guidance do not form a complete specification and should not be used as such in contracts.
Individual Chapters cover, as far as practical, the requirements for particular elements of construction. To avoid repetition, some cross-referencing is made to other Chapters, where necessary.
Occasionally, there may be disagreements on how Technical Requirements and Performance Standards are to be interpreted. Such cases are usually resolved through further consultation, failing which NHBC will exercise its right to decide, subject to appeal to an arbitrator under NHBC Rules.
Where required by NHBC, Builders must make samples of materials available for testing to ensure that they comply with Technical Requirement R3. Tests acceptable in the UK must be used when applicable. The costs of any test shall be met by the Builder if it proves non-compliance and by NHBC if it proves compliance. Materials which do not comply shall, if necessary, be removed from the site.
STANDARDS AND CODES OF PRACTICE
Where NHBC Standards refer to British Standards or Codes of Practice, other authoritative documents or technical approval certification, the documents shall be the editions current at the time of Building Regulation approval, unless other recommendations are made by NHBC in writing.
The British Standards and Codes of Practice referred to in the NHBC Standards include British Standards or Codes of Practice and those made under the Construction Products Directive (89/106/EEC) and, in particular, appropriate European Technical Specifications approved by a European Committee for Standardisation (CEN).
The UK accepts harmonised standards which are dual numbered British Standards. These have numbers issued by the British Standards Institution (BSI), the International Standards Organisation (ISO) and a European Committee for Standardisation (CEN).
Example: BS EN ISO 9000-1
Unless NHBC provides written notification to the contrary, the use of guidance in authoritative documents not mentioned in the NHBC Standards, such as BRE Digests, can be considered for acceptance.
All measurements shall be within acceptable tolerances. Where it is applicable, account should be taken of Chapter 1.2 'A Consistent approach to finishes'. In other situations, tolerances will be those currently acceptable in the industry.
NHBC is indebted to the members of the Standards Review Group, Scottish and Northern Ireland Technical Sub Committees and Standards Committee for all their work.
NHBC also wishes to acknowledge the help given by consultants, authoritative organisations, individuals and staff.
A list of the organisations who nominate representatives to the Standards Committee, Scottish Technical Sub Committee and the Northern Ireland Technical Sub Committee is shown below.
Chartered Institute of Building
Construction Products Association
Federation of Master Builders
Home Builders Federation
Institution of Civil Engineers
DCLG (Department for Communities and Local Government) (observer)
Royal Institute of British Architects
Scottish Technical Sub Committee
Homes for Scotland
Royal Incorporation of Architects in Scotland/Royal Institute of British Architects
Scottish Branch of the Chartered Institute of Building
Scottish Branch of the Royal Institution of Chartered Surveyors
Scottish Group of the Association of Consulting Engineers
Northern Ireland Technical Sub Committee
Construction Employers Federation
Royal Society of Ulster Architects
The Builder shall ensure that the work complies with the Technical requirements
In England, Wales and the Isle of Man, NHBC will generally accept work that accords with the relevant Approved Documents and their supporting documents. Exceptions would be where NHBC has a higher standard or where there is doubt as to whether the recommendation in the Approved Document is appropriate to a particular application.
In Scotland and Northern Ireland, account shall be taken of the relevant Building Standards and Regulations.
Building Regulations and rules of Statutory Authorities primarily cover matters of health and safety. Matters affecting durability and serviceability also need to be considered.
NHBC Standards do not apply to:
- health and safety matters relating to building operations
- handling and use of certain building materials
- planning matters.
Account shall be taken of:
The structure of the home shall, unless specifically agreed otherwise in writing with NHBC, have a life of at least 60 years. Individual components and assemblies, not integral to the structure, may have a lesser durability and need planned maintenance, repair or replacement during that period.
Proper account shall be taken of the use and location of materials, products and building systems in relation to:
- durability of both the structure and individual components and assemblies
- geographical location
- position on the site
- position within the structure.
Equivalents to British Standards or technical approvals authority shall be those accepted in the UK.
The Builder shall ensure that:
The following shall be designed by Chartered Civil or Structural Engineers whose status (including professional indemnity insurance) is accepted by NHBC:
Other structural elements may be designed by a Chartered Civil or Structural Engineer or others whose status (including professional indemnity insurance) is accepted by NHBC.
The structural design shall take account of the durability requirement in Technical Requirement R3 Materials requirement.
In England, Wales, Northern Ireland and the Isle of Man, structural design may be undertaken by the Builder's own Engineer or a Consulting Engineer employed by the Builder. Where specialist subcontractors undertake the design, it must be separately appraised by the Builder's own Engineer or by a Consulting Engineer employed by the Builder to ensure that the site investigation, choice of foundations, siting and construction of dwellings are properly taken into account and that the design is appropriate for the loading and conditions.
In Scotland, the Engineer shall be independent of the Builder and specialist subcontractor.
Account shall be taken of all parts of the following Eurocodes and their respective National Annexes.
|BS EN 1990||(Eurocode 0)||Basis of structural design|
|BS EN 1991||(Eurocode 1)||Actions on structures|
|BS EN 1992||(Eurocode 2)||Design of concrete structures|
|BS EN 1993||(Eurocode 3)||Design of steel structures|
|BS EN 1995||(Eurocode 5)||Design of timber structures|
|BS EN 1996||(Eurocode 6)||Design of masonry structures|
|BS EN 1997||(Eurocode 7)||Geotechnical design|
Alternatively, designs in accordance with BS 8103 'Structural design of low rise buildings' will be acceptable.
- require the Engineer to issue clear instructions for site personnel
- not permit departure from the design without the Engineer's written consent
- require the Engineer or his representative to carry out such inspections as may be required by NHBC to ensure the adequacy of the design and construction.
The Engineer shall satisfy himself that the design is suitable for the conditions encountered on the site of each dwelling.
- produce such design documents, calculations and prescribed forms of certification as NHBC requires for scrutiny
- provide design documents and assembly instructions, solely for the use of NHBC staff
- arrange for NHBC staff to have access to places where off-site fabrication is taking place.