Brandskyddat trä – egenskaper och användning, state-of-the-art

The aim of this project was an inventory of fire retardant treated wood, fire-retardanttreatments, properties, and use in different applications, and to analyze the possibilitiesfor the future. The project was funded by TCN – Träcentrum Norr. Expected industrialbenefit was an update of knowledge for wooden buildings.Fire retardant treatments can improve the reaction to fire properties of wood and thehighest fire classifications for combustible products can be reached, for example class Bs1,d0. This means that visible wood surfaces can be used in higher and larger buildings.Fire retardant treatment has no or very limited effect on the fire resistance of structuralelements, as the charring rate is hardly changed. One exception is intumescent fireretardant paints that swell and may postpone charring and thus increase the fireresistance. However, the improved fire behavior of many fire retardant treated woodproducts deteriorates over time, especially at outdoor use due to leaching. A system ofdurability classes has been developed as a complement to fire classes and makes itpossible for potential users to find reliable products for different uses. Fire retardanttreated wood products can maintain their properties after accelerated and/or natural agingif the retention levels are high enough, but many products are losing their firecharacteristics during aging. Paint systems are usually needed at exterior applications tomaintain the fire performance properties. The main use of fire retardant treated wood is asvisible wood surfaces indoors, such as in escape routes, apartments in high-rise buildings,public buildings and sports arenas. Documentation of long-term properties should beincluded to support the use of reliable fire-retardant wood, especially important forproducts to be used outdoors.Key words: Fire retardant treated wood, fire-retardant treatments, wood products, paintsystems, weather durabilit