‘Good to Know’ Knowledge Bytes

The Timber Decking & Cladding Association (TDCA) is focusing in 2022 around highlighting the key information that those buying, selling and using timber decking and external timber cladding should be aware of.

Aspecific subject is the size of cladding profiles, specifically tongue and groove (T&G) which is an interlocking system where size matters most. According to BS8605 – External Timber Cladding Part 1: Method of Specifying, for medium movement timbers such as Siberian larch, the profile width for a T&G board is restricted to a maximum of 125mm. Further guidance on tongue dimensions and movement gaps is provided, with bigger gaps and tongues being required for wider boards. At 125mm wide the standard requires a minimum movement gap (mg) of 4mm, tongue width (tw) at least 15mm and thickness (tt) at least 7.5mm. General width to thickness ratio for all profiles is between 4:1 and 6:1.

In summary, cladding boards that are essentially designed for internal use, where the effects of moisture are not so important, should not be used externally. T&G boards should not be fitted tightly together even though there may be a strong temptation to do so. Allowing for the natural movement of the timber mitigates problems arising; tongues don’t become disengaged, and the cladding stays secured to the wall – so long as the correct fasteners are used, but that is a topic for another day. Cladding suppliers need to signpost customers to the correct profile for the end use and would be wise to comply with the guidance in BS8605. This standard (which may be updated soon) remains a relevant document and contains guidance on other cladding profile styles including rectangular, shiplap, parallelogram and featheredge.

Regarding decking, our attention is on one of the most common deck issues – early joist failure. When selecting materials the emphasis is often on the deck boards but consideration to the deck substructure – posts, beams, joists, blocking and bracing – is just as important as it forms the foundation to the whole project. Pressure treated softwood is the go-to material for deck substructure components. To ensure it is fit for purpose it must be preservative pressure treated to a Use Class 4 level of protection, irrespective of whether the material is in ground contact or not. This reclassification to Use Class 4 is a recent change which the industry is gradually adapting to. Availability of UC4 treated joists is increasing especially through companies who are members of the TDCA. An industry campaign highlighting the importance of correctly treated timber is currently being promoted throughout the timber supply chain – learn more at the Wood Protection Association website: www.thewpa.org.uk/make-sure-it-s-4

Getting the fundamentals right at the beginning of any decking or cladding project is key to both customer and seller satisfsaction. Armed with the appropriate products and information helps to ensure problems are kept to a minimum.

For those looking for added assurances of quality, the TDCA operates DeckMark and CladMark quality accreditation schemes which cover products, suppliers and installers. They provide audited verification of compliance with good manufacturing and supply practices and sound installation techniques trusted by the TDCA and the wider industry.

Want to become accredited? Contact the TDA directly at  info@tdca.org.uk. Only quality oriented companies should apply. For summarised guidance, The Timber Cladding Handbook produced in collaboration with the Timber Trade Federation is available for £12 (inc p&p) from the TDCA website  www.tdca.org.uk/publications

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The importance of choosing the right fasteners for your outdoor projects

Rothoblaas is the one-stop partner for reliable and comprehensive advice for all those involved in timber construction and thanks to its outdoor fastening solutions, designing and building elegant and durable terraces will be an experience that will give you a huge satisfaction.

The durability of a wooden terrace depends both on a correct choice of raw material, and on attention to the construction details. In general, the direct contact of the wood with the foundations should always be avoided, just as it is fundamental to keep some distance between the planks and battens to guarantee ventilation and avoid the risk of stagnant water and the consequent and rapid deterioration of the terrace.

Here we present you three products that will make your terrace elegant, durable, and aesthetically beautiful:

TERRALOCK

The concealed connector, quick to assemble, which contributes to the durability of your terrace, while ensuring an aesthetically pleasing result. The 8mm footprint promotes micro-ventilation between the boards and laths of the under construction, while the concealed screw fastening preserves the surface of the boards.

KKT COLOR A4

Screws not only have the task to keep materials together, but also need to endure and support a functional structure. The durable KKT COLOR A4 screw is specifically conceived for the external use: its stainless-steel coating satisfies the highest standards of corrosion and environmental certifications, making it the safest choice for operating in aggressive weather conditions. Its triangular and inverse underhead thread allows excellent grip and wood penetration while its conical coloured head, available in black, grey or brown colour, effectively conceals with the surroundings.

ALU TERRACE

Constructing decks on aluminum substructures will grand great durability and ALU TERRACE are aluminium profiles for patios that allow to create a great long-lasting substructure to your terrace.

Whether a terrace, external cladding or a complete garden redesign is being considered, regardless of the complexity, Rothoblaas provides all the know-how needed to unleash your imagination.