Trial by fire: testing a ‘bushfire-proof’ house design
CSIRO scientists ‘flame-tested' a steel-framed house near Mogo on the NSW south coast at 2pm Friday to see how the structure withstands realistic bushfire conditions.
Constructed almost entirely from steel and featuring a non-flammable roof cavity, the house may provide a straightforward and affordable building option for bushfire-prone areas.
CSIRO bushfire researcher Justin Leonard says experienced fire researchers consider that a house constructed predominantly of steel should be able to survive in the flame zone of a real bushfire, assuming that windows or other external openings have not been breached.
The concept is that the entire non-combustible building façade, insulation and frame acts to protect the habitable space.
A range of bushfire conditions were used in the test, from ember attacks to engulfing the structure in flames.
“The flame-test will also provide information for building policies relating to bushfire areas by providing supporting evidence for use by building authorities across Australia,” Mr Leonard said.
The test house is a small low-rise building approximately 8 m x 4 m x 5 m high and includes most of the features of a domestic house.
The house consists of an elevated steel framed floor, steel wall framing with steel cladding and plasterboard lining and a steel truss roof with steel roof sheeting and a plasterboard ceiling. It includes steel fascia and various soffit linings. The side that faced the fire front has two windows and a door.
New building codes, introduced after the Royal Commission following the Victorian bushfires in February 2009, specify that: “A building that is constructed in a designated bushfire prone area must be designed and constructed to reduce the risk of ignition from a bushfire while the fire front passes“.
“This means that the building needs to be resistant enough to protect life and minimise the loss of the building,” Mr Leonard said. “This test house has been designed to meet this requirement and the trial burn will test how it shapes up against the performance requirements of the new building codes.”
The test was staged at the Eurobodalla Rural Fire Service Training Facility near Mogo in NSW – the only facility in Australia with a bushfire flame front simulator that enables testing of different materials in the open under realistic bushfire conditions.
Bushfire researchers from CSIRO and the Bushfire CRC observed the house burnover from a safety area, monitoring live feeds of data from numerous sensors and heat measuring devices embedded in the house frame.
In a bushfire event about 10 per cent of the houses are in the flame zone directly affected by fire. While safe evacuation is the cornerstone of any bushfire plan, it is vital to ensure that houses that end up in the direct path of a fire are as resistant as possible.
Testing is being conducted in partnership with the construction industry body, the National Association of Steel-Framed Housing, the Bushfire CRC and with support from the NSW Rural Fire Service.
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