Bushfire resistance of external light steel wall systems lined with fibre cement boards

Bushfires/wildfires have become a widespread and frequent occurrence in many parts of the world. With the adverse effects of climate change and the increasing population in the Bushland Urban Interface (BUI)/Wildland Urban Interface (WUI), ensuring adequate bushfire resistance of buildings in bushfire-prone areas has become very important. Improving the safety and integrity of the external building envelope is identified as a solution to minimise the bushfire related building damage and losses. This paper presents the details of bushfire resistance experiments conducted on external Light gauge Steel Framed (LSF) wall systems and the results. These LSF wall systems were externally lined with fibre cement boards and exposed to both bushfire radiant heat and flame zone fire conditions under indoor and outdoor test conditions. The results have shown that the rapid increment of the heat flux led to sudden explosive failure of the wall system whereas the gradual increment of the heat flux resulted in a progressive failure. This study has highlighted the importance of external cladding integrity and thermal shock resistance of building elements to enhance the bushfire resistance of buildings.