Sizing of members
2B1. Guidance on the sizing of certain members in floors and roofs is given in ‘Span tables for solid timber members in floors, ceilings and roofs (excluding trussed rafter roofs) for dwellings’, published by TRADA, available from Chiltern House, Stocking Lane, Hughenden Valley, High Wycombe, Bucks HP14 4ND.
Alternative guidance is available in BS EN 1995- 1-1:2004 Design of timber structures with its UK National Annex and additional guidance given in BSI Published Document PD 6693-1:2012 and also BS 8103-3:2009 Structural design of low- rise buildings, Code of practice for timber floors and roofs for housing.
House longhorn beetle
2B2. In the geographical areas specified in Table 1, softwood timber for roof construction or fixed in the roof space, including ceiling joists within the void spaces of the roof, should be adequately treated to prevent infestation by the house longhorn beetle (Hylotrupes bajulus L.).
Guidance on suitable preservative treatments is given within The Wood Protection Association’s manual ‘Industrial Wood Preservation: Specification and Practice’ (2012), available from 5C Flemming Court, Castleford,West Yorkshire, WF10 5HW