BUILDING your house out of the very thing that fuels bushfires seems an unlikely way to fireproof it.
But research into the fire-resistant properties of log walls suggests solid timber walls can survive conditions similar to a bushfire.
Yaping He of the University of Western Sydney, his colleagues and CSIRO scientists performed tests on walls made out of thick white Cypress logs. They exposed the walls to radiant heat equal to that of a severe bushfire, in a scaled-down version of the Australian standards test used to assess materials for use in bushfire-prone areas.
"There has been anecdotal evidence that log-wood houses have survived bushfire attack," he said. "Our results give a good indication of how log wood performs."
The log walls resist burning down completely, as the initial fire heat forms a layer of char on the outer surface of the wall.
"Charred wood is a poor heat conductor and it forms a blanket that protects the inner layer," Dr He said, adding that large-scale tests were required to assess the safety of log houses in fires.
Justin Leonard is a CSIRO scientist who co-ordinated the survey investigating building safety in the aftermath of the Victorian bushfires.
He said the safety of any log wall varied depending on a number of circumstances, and said "the fact that it's a log wall doesn't change the ignition properties of the timber".
"One house might be a certain distance from the forest, so the standards might say it could be built of timber," he said, adding that the safety depended on the amount of fuel near the house and other factors. "A much surer way of dealing with the risk of external combustion is to go for a non-combustible material," he said.
Dr Tracy Wakefield, who performed some of the fire-resistance testing on log walls, now runs a business selling log homes.
A researcher from Curtin University of Technology has developed a way to make fireproof concrete from a waste product of coal-fired power stations. The CSIRO has also developed a fireproof paint.
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