The Silicone and Acrylic roof coatings contain white pigments that reflect sunlight by 85% or more and thereby reducing heat-related roof damage. They have been used on flat and low-slope roofs for more than 30 years.
Asphalt shingles are not designed to be coated, and the coatings could cause structural problems and void warranties. Even for flatter roofing, reflective coatings are not for everybody. If your roof is shaded or the crawlspace is well insulated, you may not see significant energy savings, although they could still extend the life of the roof). If moisture transmission and vapor drive conditions are prevalent then proper coatings choice and application rates should be taken into consideration so as not to trap moisture within the existing membrane assembly to be coated.
To be effective, the coatings should be applied by a professional qualified contractor, according to manufacturer’s instructions, on a clean, dry roof compatible with the particular coating of choice. They should also be kept clean to maximize reflectance and minimize damage. A bi-annual or annual Preventive Maintenance or Service Agreement is always a good idea.
The chosen roof coating should extending the life of your existing roof lasting at least 10 years. Look for CRRC or Energy Star-labeled products, which have been tested long-term. Reflective coatings typically cost $.75 cents to $1.50 per square foot for the higher quality materials at various coverage rates, which generally comes with a 10yr. product only warranty. However, if installed by the local manufacturer’s recommended qualified contractor, and if current roof conditions pre-qualify, can come with a manufacturer’s fully backed materials and labor warranty for 10yr, 15yr and even 20 years.
Tests at the Lawrence Berkeley National Laboratory have shown that reflective coatings can cut energy costs for summer cooling by 25 to 67 percent. The greatest changes were seen on buildings with lightly insulated roofs. Uncoated bitumen or tar and dark colored membrane roofing can reach 200 degrees Fahrenheit in the summer, but using a white reflective coating will keep surface temperatures under 135 degrees.
The Lawrence laboratory tests show that the best products reflect up to 85 percent of solar heat, and cause only a 9-degree temperature increase in direct sunlight.