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Housing : June 2009
Environment Feature Photo courtesy Poly-Tek entering the living areas or the residence through downlights. An independent thermal report shows significantly reduced energy loss through ventilated downlights. (For a copy of the report please call 1800 852 741.) The report supports the need for additional fire resistant enclosures when using recessed downlights that allow insulation to almost abut the downlight. The other alternative, e.g. for halogens, inAS/NZS 3000:2007, Clause 18.104.22.168, requires a 200mm clearance, which can result in a half-a-metre square, un-insulated area per downlight. The subsequent loss on the insulation’s effectiveness is severe, e.g. up to 66 per cent. From 1May this year the BCA requires that any thermal gaps, beginning at just 1 per cent, must be compensated with increased R-ratings with the insulation used. In the majority of situations this would result in substantially greater insulation costs, and ignition temperatures still exposed in ceilings with no guarantee of fire safety, saysArrowform. Construction materials Construction materials can also have a significant impact on the thermal performance of a home. Options can include lightweight or high mass construction, and the density of the material can reflect its ability to store heat.Materials with a high thermal mass include brick, rammed earth, tile and concrete. Lightweight materials include timber, compressed straw, fibre cement sheets, polystyrene boards and aerated concrete blocks. Properly positioning high thermal mass materials will help maximise their abilities to store heat, while using lightweight construction materials allows greater flexibility in design, layout and zoning. Polystyrene cladding or cladding which includes polystyrene is a lightweight construction material attracting much attention at the moment. (See p.53 for more on polystyrene cladding.) According to Poly-TekAustralia Pty Ltd, the latest addition to the Poly-Tek® building products range offers a new, environmentally friendly, cost-effective and innovative external panel system. Poly-Tek says its Enviro Panels not only provide superior insulation properties (improving energy ratings and savings in cooling and heating bills), faster installation times and design flexibility, but are also supplied pre-rendered.All that is required once the panels are installed is painting. The product consists of polystyrene sandwiched between bracing ply on the back and fibre cement sheet on the front. The fibre cement sheet has a coat of Poly-Tek render.A 150m2 walling system can be installed within two or three days, giving the builder a very quick lock-up time.As a renderer is not required, this allows the builder to complete the job himself. The bracing ply on the rear of the panel complies toAS1684.2–1999, negating the need for any other bracing ply. Builders’ paper is also not required as the brick cavity has been removed. Above: Poly-Tek’s Enviro Panels consist of polystyrene sandwiched between bracing ply and fibre cement. Left: Uni-Base Board offers an R-value of 2.7 before internal insulation. Photo courtesy Unitex 50 HOUSING JUNE 2009 Unitex’s Uni-Board is another lightweight system which promises excellent thermal properties. It uses pre-coated, mesh-reinforced, polystyrene insulation panels as a base for Uni-Base Board Render and a UnitexApplied Finish and, according to the manufacturer, it is simple to install. It allows progression from frame to lock-up very quickly, and provides a flat, even surface to help achieve a smooth rendered finish. David Speechly, part owner of BallaratAssociated Fibrous Plasters (BAP) has been in the building game for more than 45 years and says the finish is ‘almost perfectly flat’. According to David, Uni-Base Board is cheaper than rendered brick, requires no specialist tradespeople to install it, is lightweight and offers an R-value of 2.7 before internal insulation. He says he’s ‘rendered over just about everything – brick, blocks, FRC sheet’, but says Unitex Uni-Base Board is ‘the best, as far as expansion and contraction goes’. BAP has recently relocated to a new purpose-built facility where they used Uni-Base Board over a steel frame for the showroom and office building that fronts the warehouse. H For more information: Arrowform – visit www.arrowform.com.au Poly-TekAustralia Pty Ltd – visit www.polytek.com.au Unitex – visit www.unitex.com.au