More stringent legislation about ventilation in homes is impacting choices for roofing materials.Builders should consider using roof tiles rather than metal roofing if they wish to comply with tougher ventilation requirements for residential dwellings across Australia.In an attempt to tackle the growing problem of condensation in Australian houses, developers are now required to install improved ventilation and extraction systems when building a new dwelling. Under the National Construction Code (NCC) 2019, released in May 2019, exhaust systems installed in a bathroom, sanitary compartment or laundry must now discharge directly to the external air or into the roof space of the residential dwelling.The code also imposes more generous allowances for the amount of roof space required for this purpose. The roof is now required to have an open area equal to the ceiling space directly under the roof or attic space of the home.
If discharging into the roof space, then 30 per cent of the open area must be made up of ventilators located not more than 900mm below the ridge, and the remaining open area provided by evenly distributed eave vents.The changes to ventilation requirements apply to all residential detached (Class 1) homes built after the introduction of the NCC 2019. Scott Kind, national contracting and operations manager at Bristile Roofing, says that while the construction industry is still scrambling to absorb the new regulations, brick roofs, with their higher pitch, do offer better ventilation than skillion metal roofs, which are widely used in Australia.“Basically, roofs with a pitch under 22 degrees require twice as many ventilators,” he says. “But since the majority of tiled roofs are higher than 22 degrees, they naturally have an advantage over low-pitched skillion roofs which might require up to eight ventilators.” Bristile already supplies a number of suitable roof ventilators, such as the Windmaster and Supavent systems, which reduce roof space temperature by up to 17.5 per cent, minimise moisture build-up and create a more pleasant living environment.
According to Kind, tiled roofs have several natural environmental advantages over metal roofing. Terracotta tiles, such as Bristile’s La Escandella range, are fire-resistant and are lower in embodied energy than many commonly used building materials, such as metal.Testing on similar coloured roofing products shows that terracotta roof tiles can reflect more heat away from a house, resulting in lower cooling requirements when compared to other commonly used roofing materials.
Bristile’s concrete roofing products provide another affordable option to metal roofing. Available in a huge range of colour and profile combinations, these concrete roof tiles are similarly fire- resistant, can result in lower cooling requirements and are excellent sound insulators. While fitting extra ventilators and air vents is a fairly straightforward procedure, Kind says that the provisions under NCC 2019 for flues is far more problematic given Australia’s history of devastating bushfires.“At this stage, roof ventilators and powered vents are not a problem, but we’re working with other industry leaders to get a compliance flue,” he says. “Flues are commonly used in Western Australia but not used much in New South Wales, Victoria and Queensland.”