Roofing Battens are a structural timber that are designed to have adequate strength to support the dead, imposed and wind loads on the roof clad with tiles, slates or shingles. To meet these performance requirements a specification has been developed that encompasses:
- Species of Timber
- Dimensions
- Size & Type of Knot
- Wane
- Rot, Decay & Insect Attack
- Slope of Grain
- Distortion
- Fissures
- Rate of Growth
Extensive testing was carried out at the BRE to confirm the grading rules, these are now set out within BS 5534:2003+A1:2010.
Following testing HSG33 – Health & Safety in Roof Work, is to be revised. The HSE now recognises that pre-graded 25×50 battens, that meet BS 5534, can be used as a foothold when fixed to rafters set at 600mm centres. If graded battens are used this way then the following safe system of work must also be used:
- the battens are at least 1.2m long to ensure they span a minimum of three trusses.
- the battens are only fixed with the recommended nails.
- the safe system of work dictates that the roofers never deliberately walk on the battens mid span, between the trusses.
- the safe system of work dictates that the roofers always walk on the rafter line when installing the tiles and slates.
This makes it even more important that battens ‘make the grade’. In BS 5534 battens are load sharing, with this new HSE ruling battens in these circumstances are no longer load sharing and an individual failure can have serious consequences.
The use of ungraded battens can put the safety of the operative at risk, which can put the contractor at risk for breach of his ‘Duty of Care’.
It is not the job of the roofing professional to grade timber battens. All other timber products are supplied to site graded and fit to use; importantly they are also graded in factory controlled conditions within a quality assured production process.
The NHBC have recently recongised this and it is now a requirement that only factory graded battens are used on NHBC sites (see NHBC Technical Extra, October 2011, Issue 04).
Grading on site is now more complex as battens are produced in more countries and from various log sizes and different sections of the log. This gives rise to additional and more complex knot structures to grade and the increased probability of defects, such as slope of grain and distortion, see the John Brash Grading Guide for further information.
Latest updates to the British Standard in the form of BS 5534:2003+A1:2010 sets out new requirements covering these areas. However, this update does not alter the fact that formal training for the roofing trade in grading battens is still in its infancy, with many roofers simply lacking the knowledge to carry out the process on site.
Please see the Roofing Battens Checklist to make sure your battens make the grade.