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Housing : March 2009
Roofing Feature Photo courtesy MiTek Above: Products such as MiTek’s PosiTrusses expand a roof’s design capabilities. Structure The method of erecting the structural roof frame has also developed over time to become more cost effective and less time consuming. The variation in techniques and materials can also increase construction capabilities and architectural freedom. Once constructed on site over a number of weeks by highly- skilled carpenters with precision mathematics, roofs can now be installed in a matter of days with prefabricated roof trusses, and fabricated off site to suit the specific project layout. Roof trusses too are constantly being developed. A company with a history of leading developments in truss manufacture and fixings is MiTek. MiTek’s PosiTrusses offer versatility in design, are fully customised and are quick and easy to install. They are a vast improvement on the bygone traditional solid timber framing systems. Their lightweight construction means they are easier to handle. The open-web truss design means greater accessibility for services such as electrical, heating and cooling systems without the need to cut through timber members and subsequently reduce its strength. With PosiTrusses, greater spans can be achieved, eliminating the need for numerous internal load-bearing walls, enabling the creation of larger open areas, and increasing architectural possibilities. The wide chord surfaces ensures easier fixing and enables the truss to be placed upright while requiring minimal temporary bracing. PosiTrusses make it possible to create everything from flat to curved structures without compromising structural integrity and are of particular use where height restrictions are an issue. Water-proofing New methods to ensure a roof is waterproof are constantly being developed and products must address a number of factors to keep up with the market and conform to the building regulations. The most persistent element and most difficult to control is water entry at all joints. Flashings and other waterproofing products are used in situations where they must defend against the three mechanisms of water penetration – HOUSING MARCH 2009