Traditionally Australians believe that using a light colour on the roof will keep the building cool. Ventilation products such as whirlybirds are also well-known. These measures can assist in keeping the space under the roof only 2 – 3 degrees cooler; not having a significant impact on internal temperatures.
If one uses light roof coating, around 50% of Total Solar Reflectivity (TSR) can be achieved at first. A new bright white roof surface can originally reflect up to 65% TSR, and make it cooler at least for the first summer.
Before long, usually within the first two years of a standard roof coatings life, it will begin to break down; one may notice a white substance that wipes off as the solvents and polyester break down and the roof quickly becomes non reflective.
So a bare or only slightly worn roof coating in any colour, will soon be absorbing around 85% of the suns radiant heat. Conduction draws this heat into the building and soon inside the building can become about 25˚ hotter than the ambient temperature.
Using heat reflective roof coatings, one can achieve up to 90% reflectivity with white, and as much as 30% reflectivity from a dark black or charcoal coating. Different manufacturers typically guarantee significant reflectivity is retained for 10 to 15 years.
A reflective roof coating will prevent the heat build-up in the first instance; keeping the building more in line with the ambient temperature. A treated roof is proven to reduce the roof top temperature up to 40 degrees, and inside the building up to 21 degrees.
It pays to research the manufacturer carefully and scrutinise the warranty, as there are some imported paint additives available that often lose up to 30% of TSR within the first 12 months.
Heat Reflective Coatings offer a wide range of high quality heat reflective insulating paints. These paints are Australian made and some good performers have been manufactured here for many years.
A full range of big brand heat reflective insulating paints are available Australia wide at Heat Reflective Coatings website, with a commercial applicators network extending nationally. For domestic coloured roof coatings people can visit the Cool Paints website, customers can order on line and have products delivered, or use the national applicator network.