Remind your customers to check timber cladding

timber cladding

A recent flurry of cladding inspection requests received by the Timber Decking and Cladding Association has revealed that basic, fundamental installation principles for timber cladding are being ignored. 

Timber cladding is often installed as a rainscreen on buildings across the UK. To operate correctly as such, the cladding must be fitted over a drained and ventilated cavity, to allow air to flow, moisture to escape, and to give the cladding the longest possible service life.

Ventilation provision is allowed for at the top and bottom of the cladding, while the batten layer or layers – one or two depending on the orientation of the cladding – creates a continuous drainage plane. A waterproof breather membrane is then situated behind the support battens, which separates the external wet zone from the internal dry zone of the building.

Unfortunately, several cases where this guidance has not been observed have recently been brought to the Timber Decking and Cladding Association’s (TDCA) attention, and it seems TDCA is not alone.

In a recent newsletter, the National House Building Council (NHBC) also reported that it ‘has recent experience with the design life of timber cladding being less than intended, leading to loss of performance and claims’.

The NHBC report further sites ‘lack of detailing to enable drainage and ventilation’ as one of the key problems, as well as the use of ‘unsuitable film-forming coatings that can trap moisture’. These are all very important factors that builders and tradespeople must get right to prevent getting callbacks from unhappy customers when future problems arise.

Merchants who specialise in timber products would be wise to remind their customers to double check that the timber cladding they install is correctly designed to provide adequate drainage and ventilation. This will help encourage best practice among tradespeople in the industry, reducing the number of complaints, and will also reassure customers that they are buying from expert, knowledgeable merchants who will always support them and their businesses with best practice advice.

Fixings are also an area where timber cladding installations can fall short when not installed or specified correctly.

Janet Sycamore, Director of TDCA, explains: “Fixings issues have long since been a bug bear of the TDCA in respect to both timber cladding and decking. Most of the cases we see feature problems caused by using the wrong type of fixing, fixings made of the wrong material, or their incorrect placement and poor application. If you get it wrong the result could be at best permanent, dark, unsightly rust stains or, at worst, boards becoming detached and potentially causing harm.”

The good news is that these problems are easily avoided by following good practice guidance available from the TDCA and Timber Development UK.

Our Timber Cladding Handbook aims to provide definitive guidance on how to correctly design, specify and install timber cladding.

The publication, produced in collaboration with the TDCA, Wood Protection Association and our educational partner Wood Campus, aligns with British Standards where applicable, making it an authoritative document on which merchants and their customers can rely.

Merchants and their customers can download a free pdf copy of the Cladding Handbook online from

  • This article was written for the April issue of Builders’ Merchants News magazine.