The primary options for coating an asphalt roof are white polymers (like those manufactured by Conklin Roofing Systems and asphalt-like resins with reflective aluminum flakes. Both are reasonably priced, and offer a quick payback.
Why install a reflective roof coating?
Flat asphalt roofs can reach up to 200 degrees, absorbing up to 70% of the solar heat. By contrast, the best reflective roof coatings reflect up to 80% of solar heat, and can reduce roof surface temperatures by 80 degrees.
Reflecting a significant amount of solar heat can cut internal building temperatures by up to 10 degrees, increasing the effectiveness of the roof insulation and cutting cooling costs by 25-70%. It also makes the building more comfortable in areas that are not air conditioned, and the roof will last longer without the heat-related cracking and deterioration, which saves you money on labor and materials in the long run.
About white reflective roof coatings
High-quality white roof coatings like those from Conklin are made with acrylics or similar materials mixed with an opaque, white and reflective pigments. They are the most effective reflective coating for the majority of asphalt roof systems. There are also polymeric coatings that are tinted for aesthetic reasons, but they are less reflective and won't save as much on energy consumption.
Tests at Oak Ridge National Laboratory and Lawrence Berkeley National Laboratory have consistently demonstrated that white elastomeric coatings offer about 60% solar reflectance, leaving the roof temperature only 36 degrees higher than the ambient air temperature - a much smaller difference than the surface temperatures on a black asphalt roof. All roof coatings must be chosen and applied carefully, particularly on rough asphalt roofs.
Calculate your potential savings from installing a white roof coating
The federal government does not offer energy saving rebates for reflective roof coatings (although some states do), but you can look for Energy Star-rated roof coatings, which guarantee a minimum level of reflectance.
Oak Ridge National Laboratory and Lawrence Berkeley National Laboratory also have a roof savings calculator that uses weather data and your building information to estimate the cost of a new roofing system or coating and the potential energy savings. After you plug in data, the lab will email you results.
ROOFING CONTRACTORS NEEDED IN MULTIPLE STATES!