Flammability study of decking sections found at the Wildland–Urban interface at different scales

This work presents a study of the fire reaction of two types of decking sections (wood and thermoplastic) exposed to a radiant heat source. The flammability was studied at two scales: a cone calorimeter was used at product scale (36 cm2) and at assembly scale (around 1300 cm2), experiments were performed under a Large Scale Heat Release calorimeter with a radiant burner. Since the wood decking sections have gaps, the influence of the orientation of the sections facing the burner was further investigated. At product scale, the wood sections ignite sooner than the thermoplastic sections whereas the thermoplastic sections have a higher peak of heat release rate. At assembly scale, the thermoplastic decking sections ignite sooner and have a higher peak of heat release rate than wood decking sections, regardless of the orientation adopted. Wood sections with boards oriented perpendicular to the burner ignite sooner and have a higher peak of heat release rate than those oriented parallel. The fire tests at both scales highlighted the influence of the shape of the products on their ability to ignite. Flame retardant should be included in decking assemblies to decrease the fire risk at WUI.