Battens have a specific standard and quality requirement and this is explained in BS 5534.
- They are a structural element of the roof and give rigidity to the structure, particularly when modern trussed rafters are used.
- They are primarily used not only to locate the roof covering in straight, consistent rows but critically, to provide a strong anchor for the nails and clips used to secure the tiles or slates. A sub-standard timber batten may not provide sufficient pull-out resistance for the fixing nails, leading to subsequent failure of the roof.
- They are load bearing and must be strong enough to carry the “dead loads” (weight of the roof covering and possible standing snow) and “imposed loads” (wind) of the roof. Did you realise that an average house roof covered in concrete interlocking roof tiles carries approximately 5 tonnes of concrete on it?
- The HSE Guidance Note, HSG 33, states that the only safe method of working on a roof with rafters set at 600mm centres (typical for new build) is by using graded battens to BS 5534.
As well as size, the British Standard deals with various other defects typical to timber, which the roofing contractor has to consider when sourcing his material. These include:
- Slope of Grain.
- Face knots and side knots.
- Resin Pockets.
- Insect attack.
- Rot and decay.
- Splits and fissures.
- Preservative treatment.
In addition, each piece of batten has to be clearly marked with the following:
- The name or identity of the supplier.
- The sectional size.
- The timber species type.
- The grade of the batten/Graded BS 5534
The rules governing the types of roofing batten allowed are all contained within the British Standard Code of Practice for Slating & Tiling, BS5534: 2003+A1:2010 which specifies the type and size of timber to be used for different rafter spacings and roof coverings, and any defects that can and cannot be allowed