Fire Scenarios for Multi-storey Façades with Emphasis on Full-Scale Testing of Wooden Façades

This paper briefly reviews the main fire scenarios for exterior façade claddings on multi-storey buildings, together with available full-scale test procedures and performance requirements in different countries. It is obvious that there is no international agreement or approach on how to evaluate the fire safety of façade claddings. Two series of full-scale fire tests of wooden façades, in accordance with the Swedish SP Fire 105 test, are presented: one series for different proportions of untreated wood (partial wood and structural fire protection with a fire shield above the window), and another series for fire-retardant-treated wood. The results are compared with data from the intermediate scale Single Burning Item test and the small scale cone calorimeter test. A main conclusion is that SP Fire 105 is a useful tool to evaluate the fire behaviour of façade claddings, but it should be complemented with more objective measurements. Claddings with partial wood and the use of a fire shield above the window fulfil the requirements. Wood claddings treated with fire retardants (FR) may fulfil the requirements, if the amount of FR is high enough. It is also essential to demonstrate the weather durability of the FR treatment. Good agreement has been found with the other test methods used. The need to use fire stops behind multi-storey façade claddings to avoid the spread of fire in cavities is underlined.