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British standards

Relevant to engineered floors
BS 5268 : Part 2 - Structural Timber Design

Relevant to timber frame
BS 5268 : Part 2 - Structural Timber Design
BS 5268 : Part 6.1 - Timber Frame Walls - Dwellings Not Exceeding 7 Storeys
BS 5268 : Part 6.2 - Timber Framed Walls - Buildings Other Than Dwellings

Relevant to roof trusses
BS 5268 : Part 2 - Structural Timber Design
BS 5268 : Part 3 - Trussed Rafter Roof Design & Construction

For further information on the standards and products that conform please contact Cullen Technical Department at 01592777570.

BS 5268: Part 2 (EF & TF)

Scope: Permissible stresses and design rules for structural timber elements.

Status: The content of the final amendment to BS5268-2 has now been decided upon, and has been circulated for public comment. Awaiting publication.

Comments: New clauses on design for disproportionate collapse are included, as are corrections/amendments as a result of the publication of CEN standards. Floors which do not possess lateral load distribution measures such as intermediate blocking/strutting (eg I-joist floors) will now be limited to a maximum deflection of 0.003 x span or 12mm, whereas floors containing such transverse stiffening members can continue to be designed to a maximum deflection of 0.003 x span or 14mm. This falls in line with the position already adopted within NHBC Standards as a condition of NHBC warranty. Future work in this committee will now be directed toward the production of supplementary design guidance to sit alongside EC5 and its National Annex, which will be published by BSI in due course as BS PD6693.

BS 5268: Part 6.1/6.2 (TF)

Scope: Part 6.1 - Timber framed buildings up to 7 storeys Part 6.2 - Timber framed buildings other than dwellings.

Status: The re-drafting of BS5268-6.1 is now complete. Awaiting publication.

Comments: The revision extends the scope of Part 6.1 up to buildings 7-storeys high, but with a number of design provisions having been tightened-up or clarified along the way. Part 6.2 will be similarly amended and republished in 2008. Attention within the timber frame sector will now be concentrated on deriving and proposing a new method for timber frame design for inclusion in EC5, as neither of the two existing methods it contains will give designs which are particularly satisfactory in the UK when Eurocode comes into effect in 2010.

BS 5268: Part 3 (RT)

Scope: Rules for the design and construction of trussed rafter roofs.

Comments: Work has begun on the production of a new British Standard which is equivalent to BS5268-3 but which contains all information necessary to design and manufacture trussed rafters to the new European standards such as Eurocode 5. A meeting of the trussed rafter code committee is anticipated in early 2008 to review the first draft, and to progress this to publication sometime in 2009, in readiness for the expected withdrawal of BS5268-3 in 2010.

The 2006 revision of BS 5268-3 extends the range of standard bracing solutions contained in its Annex-A to cover roof spans up to 17m. The bracing solutions for the longer spans involve the use of 47x220 timber bracing shelf, which must be supported by a bracket arrangement as per figure A.8 and A.9 of Annex A.

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