Concrete tile roofing assemblies (flat and profiled tile) as well as terracotta tile roofing assemblies (flat and profiled tile) commonly used in the USA, Australia, and elsewhere were exposed to wind-driven firebrand showers with an average mass flux of 10 g/m2s at a wind speed of 9 m/s. The purpose of these scoping experiments was to determine if firebrands were able to penetrate the tile assemblies and melt the sarking material. Wind-driven firebrand showers were generated using the NIST Firebrand Generator (NIST Dragon) installed inside the Building Research Institutes (BRI) Fire Research Wind Tunnel Facility (FRWTF) in Tsukuba, Japan. No decking was included in the roof support structure as these experiments were intended to replicate Australian construction details. The results, however, are relevant to USA construction since the same concrete (flat and profiled) and terracotta (flat and profiled) tiles are used in both countries. Underlayment or sarking, in the form of a layer of aluminium foil laminate bonded with a fire retardant adhesive to a polymer fabric, was placed under the tile battens. The results showed that firebrands penetrated the tile gaps and subsequently melted the sarking material for both types of concrete tile roofing assemblies (flat and profiled tile) and the profiled tile terracotta roofing assembly when exposed to wind-driven firebrand showers. The flat tile terracotta roofing assembly performed best probably due to its interlocking design. For these tiles, the firebrands were observed to become trapped within the interlocking sections of the tiles and as a result, the firebrands were not transported past the tiles towards the sarking material.
Citation: Technical Note (NIST TN) - 1794
NIST Pub Series: Technical Note (NIST TN)
Pub Type: NIST Pubs