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Are you correctly specifying timber cladding battens and deck substructure members


Sourcing products and designing for longevity are the most popular enquiry types being received by the Timber Decking and Cladding Association (TDCA) helpdesk.

In response, the organisation is urging designers and users of timber to tighten up on specifications by being clear about the requirements of timber durability to be in line with relevant standards.  In particular, the TDCA is focussing on cladding battens and deck support structures as these can be overlooked; pressure treated timber being the most popular choice for these components.

Designing to a 15, 30 or 60 year desired service life for external timbers is the standard criteria. The service life is achieved through good design detail coupled with selecting materials of appropriate quality.

Cladding battens are assigned to Use Class 3 (exterior above the ground) and should be pressure treated accordingly.  Roofing battens are a lower specification at Use Class 2 and so should not be used to support cladding.

Likewise for timber decking substructures – using internal roofing joists is a definite no-no! The TDCA with other industry bodies is now recommending that all decking substructure components are treated to a Use Class 4 specification.  Use class 4 covers timber used in external ground contact and as exterior structural supports.

With sourcing the correct quality presently difficult, it could be tempting to compromise on quality.  However, the TDCA is stressing that any corner cutting now, is likely in time, to result in costly failures.

The TDCA offers a sourcing service – contacting potential suppliers on your behalf to provide a list of companies who can meet your specific needs.   The TDCA’s member database not only includes timber suppliers but also providers of fixings, fasteners, coatings, insect mesh, membranes and pedestals.

Sourcing third party accredited materials will help in the pursuit of acquiring quality, fit for purpose products; look for the DeckMarkTM and CladMarkTM badges – they are the quality accreditation schemes operated by TDCA for its members.

TDCA has an array of free online resources covering this and other subjects which are designed to help specifiers, designers and installers to design for durability.  You can also access technical help and guidance if you have a specific question.

The Timber Decking and Cladding Association | www.tdca.org.uk | 01977 558147 | info@tdca.org.uk
Office 5 The Walled Garden, The Nostell Estate, Nostell, Wakefield, WF4 1AB

The Timber Trade Federation | www.ttf.co.uk | 020 3205 0067 | ttf@ttf.co.uk