The dangers of inadequate or ungraded battens

Because timber is a natural material, knots, splits and other imperfections can often be found in timber products. When it comes to roof battens, if the wood is flawed, it can lead to serious  consequences. That’s why grading to BS 5534 is such an important step, as it ensures the performance, durability and safety of the roofing battens, as well as the integrity of the roof structure.

The importance of  graded battens

Grading roof battens means assessing them based on various criteria to determine their suitability for roofing applications.

The risks of using inadequate or ungraded roofing battens include:

• Hazardous conditions for those working on roofs
• A roof needing to be replaced due to damage or instability
• Roof tile manufacturer’s guarantees becoming invalid
• Non-compliance with roofing and wider construction industry bodies such as the NHBC, LABC, Trustmark, NFRC Co-partnership, Roof Sure and Roof Sure Plus

Roof batten quality and BS 5534:2014+A2:2018

BS 5534:2014+A2:2018, the code of practice for slating and tiling for pitched roofs and vertical cladding sets out requirements for various characteristics of timber battens to help ensure quality, durability and safety. It covers:

 

• Roof batten dimensions
• Knots and imperfections
• Splits and fissures
• Wane
• Distortion
• Slope of grain
• Rate of growth
• Insect attack, rot and decay
• Resin pockets
• Preservative treatments

 

According to BS 5534, battens should be graded before arriving at site, and each batten should be individually marked with at least four pieces of information:

 

• Supplier
• Origin (i.e. species code)
• Graded BS 5534
• Size

 

Additional documentation should also be available with the details mentioned above, as well as details on preservative treatments and any third-party accreditations.

What makes an adequate roofing batten?

Factory-graded roof battens ensure the products are suitable for the roofing application. Let’s look at some of the beneficial characteristics of BS 5534 graded  roofing battens:

 

• Loading capacity: Roofing battens are fundamental to the roof structure. They are load bearing and carry both the load of the roof tiles, as well as any other imposed loads, such as snow or wind. They are also often used as footholds during installation – the Health and Safety Executives (HSE) provides extensive guidance on this aspect of safety in its publication HSG 33 Working on Roofs.
• Dimensions: Battensshould be no less than 25mm deep. This plays a part in loading capacity and is also important when looking at the withdrawal resistance of nails. BS 5534:2014+A2:2018 specifies batten sizesbased on the span of the rafters. For example, the timber battens for Marley’s Modern concrete roof tiles should measure either 25x38mm (for rafters/supports not exceeding 450mm centres) or 25x50mm (for rafters/supports not exceeding 600mm centres).
• Consistency: Battens should be even in depth so that roof tiles or slates lay evenly. BS 5534 allows a tolerance of +3mm.
• Preservative treatments: Timber roof battens should be treated to Us Class 2 in accordance with BS 8417:2011+A1:2014, the code of practice for preservation of wood. Use Class 2 treatment is suitable for applications internally above ground, with a risk of wetting. The treatment provides protection against rot, fungi and insect attack.

To find out more, download our Guide to Batten Grading. You can also get in touch to discuss your project requirements with a member of our team.