Lucaston House at a glance Energy rating: 8.7 stars is well below what is required to meet passive ‘This is the way roofs are starting to evolve in Cost: Around $700,000 house standard. Tasmania,’ he says. ‘It’s international best practice.’ Additionally the owners supplied ‘This is very, very difficult to achieve,’ he says. The iron roof serves as a rain screen. Behind keyitems such as the oven ‘So it even surprised me. But we took quite a lot that sits a black membrane for weather proofing or Time:10 months of care with the rammed earth and the junctures sarking. A big part of passive house construction is Walls: 450mm rammed earth walls and the detailing. I don’t know of any other to have the weather-tightness layer sealed and water with 100mmXPS core Tasmanian building that has tested lower than tight. And Justin can guarantee that this one is. (by Unique Earth Tasmania) that. But there will be soon – we’re always trying ‘We had that roof without iron for three weeks Roof: Proclima Mento 3000 Connect to push the boundaries!’ and we just continued working underneath because roof membrane (sealed weathertight it was waterproof with no leaks,’ he says. layer) under counter-batten roof, The finished property is cosy and The counter-batten roof has thin strips that run Colorbondcorrugated iron above comfortable in winter, yet stays cool in down to the gutter on top of the rafters, and then Windows and doors: Unilux triple Lucaston’s warm summer months the roofing battens sit at 90 degrees to those and glazed windows and doors the roofing iron is screwed to those battens. (average U-0.8) with airtight installation ‘In normal construction you’d see the roofing Justin keeps up with a lot of passive house builders membrane go on top of those battens before the on twitter to follow the race for ever-lower air-tightness roof goes down. It’s the way we’ve done it over the results. He also watches for developments and new years, which is now not the best way to be doing techniques in passive house design. it – we learn and take notice of what’s happening One such development is the counter-battened internationally, and currently there’s a bit of a shift,’ roof structure used on the Lucaston house. Justin comments. MAY 2018 HOUSING 23 PROJECTS