Summary
• The Nordic Fire Retardant Treated Wood association (NBT) has 35 members.
• Timber building is growing across the Nordic region, but regulations require fire retardant treated material for specific applications.
• The NBT will inform and educate on fire retardant issues and specification.
• A new Nordic standard for fire retardant service classes has been launched.
The new Nordic Association for Fire Retardant Treated Wood, the NBT, was launched earlier this year by 35 member companies from the timber, fire consultancy and research sectors of Denmark, Finland, Norway and Sweden. The association is the continuation of a network started by Sweden’s Wood Technology/SP Trätek technical centre in 2007 to provide information about latest fire retardant treated products and the main reason for its launch was the increased interest from architects and builders to use them in construction.
There’s an increasing use of wood in multi-storey buildings in all Nordic countries, particularly in Sweden, where about 15% of new medium-rise residential buildings are now timber.
Load-bearing structures in the region can quite readily be made of timber, but in many cases there are restrictions on using untreated wood as visible interior surfaces in escape routes, flats and public buildings. Treated material, however, is permitted and the same is true for exterior cladding on buildings over two storeys.
The careful selection of the correct type of fire retardant formulation can overcome this concern and allow a wide range of fire retardant wood-based products to comply with even the most stringent regulations, thus extending the market use of this most natural of building materials.
The aim of the NBT is to provide a neutral and reliable platform for advanced knowledge about fire-treated wood to all sectors of the market. End users such as architects and fire consultants will be able to turn to it to obtain reliable information on fire-treated wood products for different building projects and manufacturers will be able to post the important properties of their products with the organisation, mainly concerning fire performance and service class for the applicable end use.
The organisation will explain fire retardant performance in areas such as reaction to fire and also provide information on how fire retardant properties can degrade with time, especially in outdoor applications, and stress the importance of obtaining proof of long-term fire performance.
The organisation will cover all fire retardant types and application methods; those incorporated integrally into wood composite products during manufacture; pressure impregnated into solid wood, plywood, chipboard and hardboard industrially post production; and applied, as paints or surface coatings, in situ after wood-based products are installed.
It will also advise on new product directions, such as the latest low hygroscopic and leach-resistant retardant formulations. These are being developed in response to the fact that, while most existing commercial retardants satisfy European and national classifications for combustible products in their ability to reduce different reaction-to-fire parameters of wood such as ignitability, heat release and flame spread, high retention levels have to be achieved compared with ordinary preservation treatments.
The NBT will also advise on latest legislation, codes and standards governing the market. These include a Nordic system of service classes for different end use applications that has recently been developed, with test methods and classification according to Nordtest NT Fire 054. Following this, a European Technical Specification is also in development which will be published as CEN/TS 15912. This new system covers short-term use, interior use and exterior use in buildings. It includes verification of low hygroscopicity and maintained fire performance at accelerated or natural weathering.
The Association is additionally developing new quality systems to boost market confidence in fire retardant treated wood. The first, for industrially produced products (treated by pressure impregnation or surface application), is already starting to be implemented. A second system for in situ applied products at building sites is under way. This is proving more challenging, as control methods at building sites are not yet available for FRT wood products.
The Nordic Association team comprises chairman Mikael Westin, of the Swedish Wood Preservation Association; secretary Lazaros Tsantaridis and technical consultant Birgit Östman, both of SP Trätek.
The organisation has also launched a website (www.brandskyddattra.info) to provide further information about fire retardant treated wood. This will soon be available in English.
