Study of the flame propagation from a deck slab to wooden cladding at the laboratory scale

The aim of this work is to improve the understanding of the fire behaviour of building materials used at the wildland urban interface using laboratory scale experiments. To this end, wood cladding was exposed to a propagating flame front across a decking slab. This slab element was ignited by a radiant panel. Three slab configurations were studied: thermoplastic slabs and wooden slabs with slats oriented parallel or perpendicular to the cladding. The vertical distance between the slabs and the cladding varied from 0 to 20 cm and two types of batten arrangement were used to separate the cladding from the supporting cellular concrete. The experiments first focused on the measurement of the heat fluxes received by a non-combustible wall in place of the cladding, depending on the type of slab used. Radiation was the dominant heat flux measured on the wall and it increased up to 35 kW m-2 as the flame front approached to the cladding. The spreading of the fire from the slab to the cladding was then investigated. Ignition of the cladding occurred in all configurations tested. The slab configuration (material or orientation) has little effect on the combustion of the cladding once it has been ignited. In addition, the distance between the deck slab and the cladding did not have a significant impact on the fire behaviour of the cladding, even at the 20 cm distance recommended by the standards.