Bushfire ignition of buildings: a study on decking timber and external doors

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To help reduce bushfire damage on buildings, CSIRO has done experimental research on the fire performance of decking timber and external doors. The moisture content of decking timber was recorded over three Australian summer months. It was later compared to weather station data, to see what the typical moisture content of Australian decking timber would be, during bushfire weather. Typical bushfire rates turned out to be between 6-9% and possibly lower. Also, the timber was put into a conditioning room, to investigate how long it would take to reach bushfire moisture contents. That achieved data could be used to design a conditioning method for decking timber test standards. Other tests were made on external doors and timber decks, to see how the combination of door and deck would perform in a bushfire scenario. This scenario was achieved by subjecting the doors to radiative heat, using a gas heated radiant panel. To simulate realistic ember and flame attacks, tree litter from Eucalyptus was placed close to the door and ignited. It was found that the deck used (made out of Merbau hardwood) performed well. All doors ignited within two minutes when subjected to constant flames at a background radiation of 10 kW/m2 or more. Different means of protecting the door were tested, and the most effective turned out to be a security mesh screen, which kept a hollow core door from igniting, even when exposed to 28 kW/m2 radiation. The conclusions from these tests can be used as guidelines to demonstrate how to build buildings in bushfire prone areas, and as a ...