Wood products are experiencing a renaissance as construction material in Europe due to their environmental benefits. In Norwegian building design however, timber has always played an important role but has had its limitations in urban architecture. One of the reasons is a high demand to fire safety in dense house building and multi-story buildings. Though novel construction methods and fire safety design concepts have widened the field of applications during the last years, architects and engineers still face challenges in using wood in buildings that require high fire safety. A critical point of many flame-retardant chemicals in outdoor applications is their poor fixation in wood; they are prone to migration due to moisture changes, which bears the risk of salt crystallization on product surfaces often associated with damage of coatings. Additionally, loss of the chemicals may decrease the fire performance. The draft standard prEN 16755:2014, superseding TS 15912:2012, prescribes the classification requirements for the durability of the reaction-to-fire performance of flame-retardant-treated wood products in humid conditions. The development of the TS 15912 into a European standard is an important but only a first step forward to guide planners to find suitable flame-retardant treated wood products for outdoor applications. The awarenes’ of building planners and the construction industry for choosing appropriate treatments in humid conditions has to be raised; besides, a further development of flame-retardants is desirable, which show a high leaching resistance and, at best, increase the durability against decay and discoloring fungi.
Keywords: fire protection, fire regulations, flame retardance, reaction to fire, wooden facade cladding