Know your timber roof battens

With ongoing concerns about quality variations between roof battens, Jenni Forrest, quality manager for JB Red at Marley, explains what the differences are and how to spot them.

Despite the stricter grading requirements introduced as part of BS 5534:2014 and again in amendment 2 in 2018, there are still quality variations between different brands of roofing batten. 
Just as not all BS 8612 compliant dry fix products offer the same performance levels, the same can be said of battens. While they have to meet the grading requirements set out in BS 5534, there can still be significant differences - from the way they are graded, through to the type of timber they are made from and the preservatives they are treated with.

Roofing battens are one of the most important parts of a pitched roof structure, acting as a structural and load bearing element. As well as supporting the dead weight of tiles and the imposed wind loads, BS 5534 graded roofing battens can also be used as a secure foothold during installation. That’s why checking the quality and compliance of the roofing battens you are selling is so important.
Our new training includes everything merchants need to know about battens, from what to look out for when checking and selling them, through to expert installation advice. 

Here are some of the top tips:

Selling battens – what to look out for

• Grading stamp - Only battens that have been pre or factory graded to BS 5534 are actually allowed to be called roofing battens. Make sure there is an indelible stamp on the batten saying BS 5534. 
• Batten colour - The issue of batten colour has caused some confusion. Whilst the distinctive red colour of our JB Red roofing battens does give peace of mind that you are using a BS 5534 compliant batten, this is not necessarily the case for all battens. Please don’t assume that just because it is coloured, that a batten meets the required British Standard. It must also have the correct stamps and supporting documentation. 
• Graded Timber – The type of timber used for a roofing batten is quite significant, so do check this. The species of tree from which the timber has come from should be stamped on the batten. We only use slow grown imported redwood or whitewood for our JB Red battens. All of our battens are cut from kiln dried sideboards as they are less likely to distort. Also look out for FSC or PEFC certification to ensure sustainable sourcing.
• Grading rules and process – For quality control, roofing battens must be pre-graded before they get to site, this can be done by visually grading or by a machine. We believe that only mechanical grading, using camera and laser scanning technology, is able to produce the most accurate and consistently graded roofing battens.  Our JB Red roofing battens are put through a state-of-the-art laser grading machine called Goldeneye, which scans the battens in intricate detail, by the millimetre, to deliver a high-level of accuracy, consistency and ultimately, quality assurance.
• Treatment – Roofing battens should be preservative treated to Usage Class 2 in accordance with BS 8417. Different manufacturers use their own types of preservative treatment and may offer different guarantees as a result.  JB Red roofing battens use a patented next generation technology preservative called MicroPro, which has a unique red pigment and carries a 60-year life expectancy against insect attack and wood rotting fungi (when installed correctly in accordance with the requirements of Usage Class 2).

Checking your battens - defects

As a natural material, timber battens will obviously have varied characteristics but BS 5534 is very strict about what is and isn’t allowed and our machine grading process scans JB Red battens by the millimetre to make sure they meet the requirements of the british standard. 

If you want to check all of the battens you sell are compliant, then here are some things to look out for:

• Knots - Some knots are allowed, depending on their size and position. If a knot appears on both sides of the face, the sum of the knot on both faces must not exceed the width of the batten. A knot appearing on both edges of the batten, which does not appear on the face, is only deemed permissible if the knot on either side is one-fifth of the depth or less. 

• Missing corners - BS 5534 also allows for a missing corner on the batten, otherwise known as wane. However, it is only permitted on one axis and should not exceed one-third of the dimension of each of the faces on which it occurs.

• Distortion - Battens need to be straight, so BS 5534 sets a tolerance on distortion. Bow, spring or twist should each not be greater than 5mm, measured over a length of 1.2m at a reference moisture content of 20%. If your batten is bowed more than this, then do not sell it and check with the manufacturer. Battens cut from sideboards are less likely to distort which is why JB Red roofing battens are only manufactured from kiln dried sideboards.