Hillside cuts, earth mounds required for fire safe rural housing

Peddle Thorps Peter Brook has already put some of these ideas into place to create a coordinated fire defence for his holiday house. He built the house in Aireys Inlet, on the Great Ocean Road, after the Ash Wednesday fires almost 20 years ago.

Brook said the new standards were a good start, but owners also needed to look at positioning and barriers, to avoid losing their houses and maybe their lives in a firestorm.

Careful initial siting was essential to minimise the impact of a firestorm, which on Black Saturday saw ground level temperatures of 1200, melt nearly everything.

Brook said that cutting into the slope of a hill with a bulldozer or excavator, to establish a house site that would force the full brunt of a firestorm to pass over the top of the finished building, was an obvious measure. So was clearing nearby trees.

Not so obvious in flat country, was the need to build graded earth mounds around a house site, to similarly deflect a super-heated fire storm over the resulting building.

It is essential too, to plant fire retardant trees and bushes such as boobyallas, to minimise the impact of a fire, he said.

Since building the Aireys Inlet house, and after considering the impact of the Black Saturday fires, Brook has further developed his concepts for bush fire resistant housing.

The design ideas include:

 Planting fire retardant trees, and areas of open grasses;

 Installing a sprinkler system;

 Installing pull down fire barriers; and

 Installing corrugated iron roofing with special flashing to trap sparks.

Brook said, We should be very careful we do not repeat the mistakes of the past and build the same houses in the same locations. That also can mean looking at simple things such as the location of LPG containers which can become flame throwers.

Sprinklers can be deployed around the house facing the building. After considering all the information, I rejected the idea of sprinklers watering the roof, as a fire storm would simply blow the water away, he said.

His house is built on a concrete slab using steel and decorated with hard to burn paint. To deal with the problem of flying sparks getting into the roof, Brook developed a channel running under the ridge of the roof, to catch burning material.

The basic idea is to build the entire house around a central chimney with two layers of protection against fires, such as pull down screens and other layers of protection, he said. The high central chimney provides oxygen for people after the fire storm has passed.

He reckons a basement retreat under a house will not work because as the house burns, people can simply suffocate due to lack of oxygen, even when not exposed to direct radiant heat. An option though could be to have bottled oxygen on hand.

Brook said his final design actually ends up looking like the traditional Australian farm house with a large central chimney. He said the countrys pioneers had an intuitive understanding of the risks involved with a bush fire which translated into the basic shape of their buildings.

Peter Brook is the design director at Peddle Thorp, a major architectural firm in Melbourne, and has designed many of Melbournes signature buildings such as the Rod Laver Arena.