Industry Services
Industry Services
Janet Sycamore
Timber Decking & Cladding Association
Using the wrong battens for timber cladding can compromise durability, ventilation, and long-term performance. This guide from Janet Sycamore clarifies what to specify, why it matters, and where to find help.
When it comes to supporting external timber cladding, battens play a bigger role than many realise—and using the wrong type can undermine even the best installation.
A common misconception is that roofing battens and cladding battens are interchangeable. In reality, they face different exposure conditions. Cladding battens are regarded as external and exposed to moisture entering behind the rainscreen. Therefore, they need to be pressure- treated to Use Class 3 to withstand that environment. Roofing battens are treated to Use Class 2 designed for internal building use and so aren’t designed for such exposure and shouldn’t be used in their place.
So, are you specifying or selling the correct battens for the job—here we answer some commonly asked questions.
Look for pressure-treated softwoods like pine or spruce, with a service life of 30 years or more. The product should come with a treatment certificate specifying its Use Class and intended desired service life—this should ideally align with the cladding board’s service life.
For horizontal cladding, use vertical battens, choose 50 × 38 mm or 50 × 25 mm (if there’s no side jointing). For vertical cladding, counter battens are essential to maintain ventilation and drainage – counter battens should be at least 50 mm wide and 25 mm thick.
Some suppliers offer sloped-top battens, which may help water shed more effectively into the cavity—a cautious, belt-and-braces approach, though not backed by conclusive evidence.
Strength classes conveniently define timber’s minimum strength, stiffness and density characteristics. However, strength- graded timber isn’t used for cladding battens. Instead, the battens are either sorted on-site to exclude large defects (big knots, splits, rot, etc.) or bought already graded in accordance with BS 5534 (the roofing batten standard)1 BS 5534 isn’t a strength-grading standard as such.
The wood species used for cladding battens are UK-grown larch, pine, and spruce or their imported equivalents, as defined in BS 5534. These species all have a minimum
“Roofing battens are not cladding battens—get it wrong, and even the best timber cladding can fail.”
mean wood density of 350 kg/m3 (at 12% moisture content), which gives adequate connection strength for cladding fasteners.
Provided the wood species used for cladding battens are specified in accordance with BS 5534 (code of practice for slating and tiling for pitched roofs and vertical cladding), it will meet the engineer’s minimum density requirements.
At the TDCA (Timber Decking and Cladding Association), we promote good practice and fit-for-purpose materials in external timber cladding. Time and again, we see preventable issues caused by inappropriate products or poor installation techniques. By choosing and selling battens that are truly suited for cladding applications, you’re playing a vital role in protecting the reputation of timber as a reliable, sustainable building material.
You can find practical information in The Timber Cladding Handbook, available online.
We also offer an advisory service for unanswered queries—use the Contact Us form to submit any questions.
For more detail, refer to BS 8605 External Timber Cladding Part 1 – Method of specifying, designed to help manufacturers and specifiers.2 TDCA offers a 15% discount to purchasers.
