Fire Protection Ability of Wood Coverings

The low thermal conductivity and slow charring rate of wood products may protect underlying products from being heated and ignited. A literature survey shows that such fire protective behaviour of wood coverings has been verified by different methodologies in several countries in and outside Europe. A new European system with K classes for the fire protection ability of coverings has been utilised for wood products. The classes are based on full-scale furnace testing, and the main parameter is the temperature behind the fire-exposed panel after different time intervals. Three levels are defined: 10, 30 and 60 min. An extensive test program has been performed according to the new European system. The results demonstrate that all K classes may be achieved for wood-based panels (particle board, plywood, solid wood panels, OSB—Oriented Strand Board and hardboard), and for solid wood panelling and cladding. The criteria for wood products are based mainly on panel thickness. The thickness for achieving each K class may vary slightly, depending on the wood product type and on mounting conditions and fixing means. Typical thickness to reach 10 min fire protection is 10–15 mm, for 30 min 24–30 mm, and for 60 min protection 52–54 mm. The end-use applications of wood products with K classes are mainly as wall and ceiling coverings and for protection of underlying materials and structures. Examples are protection of combustible insulation materials from being ignited, timber structures from becoming charred, and steel structures from reaching high temperatures. K classification is required by building regulations in some countries, e.g. Germany, Denmark and Sweden.