TIMBER: CLADDING
HOT TOPIC
T
he mantra of successful timber sales is ‘fit for purpose’: merchants with the knowledge to sell the correct product for the correct end use are likely to build up a reputation with customers for sound advice, and thus encourage repeat business. The ‘fit for purpose’ mantra needs to be even more vehemently repeated with timber products likely to be used in a situation that might warrant a flame-retardant treatment. It’s not the job of the builders’ merchant to know Building Regulations inside out. Nor it is the merchant’s role to create or modify the technical specification of a building. Yet while you can’t control what is specified, you can certainly raise questions with your customer. You can also make yourself aware of what treatments are available from, or via, timber suppliers, and any lead times involved in ordering. To do that you also need some basic knowledge of the language of flame-retardant treatments and how they operate. This will help you to judge whether what you’re being asked to provide, for example in the way of timber cladding, might warrant an extra question to the customer on the potential need for flame- retardants.
Builders are famously busy and some have been known occasionally to stray from the architect’s original specification on timber
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In a social media age, reputations can be made or lost seemingly in an instant. Making sure you’re up to speed with the hot topic of timber products and flame-retardant treatments could help your business to avoid taking the heat of a social media storm.
work and what are the key performance indicators to understand from the merchant’s perspective?
A timber product’s reaction to fire can be measured, tested and enhanced by the application of a WPA-approved flame-retardant (FR) treatment. These work by modifying the nature of the burning process, reducing ignitability and spread of flame significantly, and thus retarding the growth phase of a fire. It is the failure, somewhere in the construction specification chain, to recognise the need for flame-retardant timber treatment which amplified the timber balcony fire in a low-rise block of flats in east London earlier this summer. Had the timber received an FR treatment it would have behaved very differently.
products and finishes. Armed with the right knowledge, there’s no harm in the merchant asking the builder to clarify, perhaps with the original specifier of the product, whether a flame-retardant treatment might be needed. If it’s necessary to protect your reputation you can ask for clarification on paper or by e-mail, to give yourself some back-up in the unlikely event of future questions.
On the supply side, the Timber Trade Federation (TTF) and Wood Protection Association (WPA) are working closely together to provide information to the marketplace through a series of six Fact Sheets and Guidance documents, available at wood-
protection.org, in the Publications section. So how do flame-retardant timber treatments
FR treatments can be incorporated during manufacture, such as with ‘FR’ types of MDF and OSB. For solid wood, FR treatments can be applied, like other treatments, in a factory- controlled process of pressure impregnation, or applied on-site via brush-on coatings. Brush- applied coating is not recommended by either WPA or TTF, since it is difficult to guarantee whether the right depth of coating has been applied on each timber element, the coating depth being critical to performance in a fire. FR treatments, again like other timber preservative treatments, are also extremely specific to the end use situation. INT1 treatment is only for a dry interior situation; INT 2 is a humidity resistant (but not external use) treatment; and EXT is a leach-resistant treatment for external use. Merchants will also see a ‘Euroclass’ definition on FR-treated products, relating to BS EN 13501. The highest performance (on a scale where A is top and F is low) which some treated timber products can
www.buildersmerchantsjournal.net August 2019
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