Why use graded Battens?
BS5534 is the British Standard for Roofing Battens. Within BS5534 there are the specific grade and identification requirements for battens. It does not set out how or where they should be graded but that they should meet the Standard.
The requirements for roofing and tiling battens have been there for many years but it is only recent technological advances that have made the production economical on a commercial scale.
Most forms of contract and building regulations require the roofing to meet a minimum standard of BS5534 and thus implicitly the battens must meet the grade and identification requirements.
What is the process?
Roofing battens are too small to be mechanically strength graded in a ‘bending’ machine (like scaffold boards). X-Ray and Ultra sound technology, although established for larger sections has not been developed for battens.
Visual assessment is required and it can take two forms:
- Manual – individual graders visually assessing each piece.
- Machine – using a combination of laser and camera scanning.
Both should take place in a factory controlled environment and preferably with a recognised third party assessment; ideally encompassing both the process and the product. (This is only a recommendation).
Manual systems depend on the individual grader to measure the defects. Done correctly this produces accurate results. However, at commercial speeds, using typical production methods, visually grading small sections accurately can be difficult. It is also time consuming and requires a trained individual to be on site.
Laser and camera scanning takes the human error and judgement from the process. The parameters are set within the software and the result is a consistent output. Most factory controlled processes include placebo or other processes to ensure the system is correctly calibrated and the end result meets the grade.
On site grading – The Industry Perspective
There are many aspects to grading roofing battens, such as knot size, dimension,wane, slope of grain, distortion, etc . Subsequently, it is difficult and slow to do this on the roof. Additionally once graded, every piece has to be marked ‘BS5534’. It is questionable as to whether this is a practical process on site.
The NHBC insist on factory graded product. Their view is that the product should arrive on site, fit for purpose, graded to meet the British Standard requirements and that the operatives job is to install the product and not have to worry about any grading that may or may not be required. As with any building product being used, a common sense check should be given to assess for any handling damage, end splits (these can develop post grading) and any obvious error. This is very different from a full grade on site.
The HSE have revised HSG33 Health and Safety in Roofwork. The HSE only recognise that factory graded battens provide a secure foothold when installing a pitched roof (as an alternative to roof ladders). Their recommendation was updated to recently, to insist on factory graded battens for use on 600mm centres (previous advice only related to 450mm centres).
Graded battens that meet BS5534 have been on the market for a few years now but they have recently been put under the spot light with the NHBC directive that only factory graded battens should be used on NHBC sites.
Both LABC and NFRC recommend their use
There are varying opinions from across the trade surrounding battens. From the manufacturer’s perspective, Marley Eternit, are looking to raise awareness of the dangers of inadequate battens and raise the standards of batten grading throughout the industry.
Marley Eternit offers JB-RED pre-graded roofing batten, our BBA accredited premium machine graded batten; and JBi battens for use when factory graded battens are NOT required (a simple Grading Guide is produced to assist this process).