Aussies love “solid” houses. Concrete slab,masonry walls,tiled roofs. A continual reworking of the “Federation house”. But those heavy materials can only be built on-site,in traditional construction. In comparison,the “lightweight” materials in prefab manufacture are seen as just that:light weight. Thin and flimsy,it’s not “bricks and mortar”.
The recent rise in metal-clad mobile homes and shed-like “granny flats”,both mostly prefab,has done nothing to quell the disdain for the temporary,not-real-home feel. Add to that,our common experience of prefab is not great. The school “demountable”. Baking hot in summer,freezing in winter,acoustically horrible and an eyesore to boot. Or the irony that the contractors who build conventionally,work out of prefab site sheds. And can’t wait to get rid of them.
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In that uncertain market,establishing a prefab business is a big risk. The factory,with its machinery and processes,is capital intensive. A huge expense before a single house is rolled out. Most firms that have ventured that capital rely on a steady diet of site sheds,mobile homes,and mining dongas to survive. Houses are a luxury that few have as their main manufacture.
But the financial risks don’t stop there for homeowners. Banks have the same conservative attitude to “solid construction” and don’t value prefab as highly,and critically won’t lend mortgage money to pay builders for material that’s off-site. With 90 per cent of the house value built in the factory,a separate,more expensive construction loan is required,increasing costs and complexity,and often wiping out the savings being made in the factory.
All of which has doomed volume assembly,or VOLA,using whole room modules,to the margins in Australian home-building.
But there is another prefab system that shows more promise – fabricating a house on site from large,standardised or custom-made components,in a “kit of parts assembly”,or KOPA.
In this system,a “flat pack” of whole floors,walls and roofs,with modules of bathrooms and kitchens,is delivered to site,for quick assembly. This is a logical extension of the existing manufacture of components such as wall frames,roof trusses,and fully glazed windows and doors. It’s not unlike the way a certain Swedish company has the purchaser assemble their furniture. And they now sell houses using the same system.
Given how widely dispersed and relatively small by world standards the Australian house building industry is,this seems a far more logical direction to go for prefab.
Tone Wheeler is president of the Australian Architecture Association and the design director of environa studio,which specialises in social and sustainable architecture.