External timber framed walls

6.2.3Design checking and certification

Design of the superstructure shall be adequately checked.

Homes with a timber frame superstructure require certification confirming that the design has been checked by an NHBC approved timber frame certifier.

The timber frame certifier should:

  • be listed on NHBC’s list of timber frame certifiers
  • be a suitably qualified civil or structural engineer with a minimum of three years’ experience in timber frame construction
  • not be the designer of the timber frame
  • complete and sign a certificate confirming assessment of structural adequacy for each specific project
  • provide the registered builder with the completed and signed certificate.

The registered builder should ensure that the completed timber frame certificate is available on site for inspection by NHBC.

Contact NHBC Standards, Innovation and Research:

  • if you require contact details of frame certifiers, or
  • to apply to become a timber frame certifier.

Alternatively, timber frame superstructures from Gold level members of the Structural Timber Association’s Assure scheme, who have engaged Silver/Gold level structural designers and engineers, are acceptable without additional certification.

The registered builder should ensure that a letter from the manufacturer is available on site for inspection by NHBC.

Designs should be submitted to NHBC when proposed buildings are four storeys or more and the floor joists are solid timber.