Roof Coating: A Sustainable Option
Maybe the budget is too tight for a tear-off or you need to squeeze more life out of an aging roof – whatever the reason, roof coating is a sustainable option to consider. Not all roofs will qualify though.
Turning a Black Roof White
Covering a black roof with a white reflective coating reduces the amount of heat absorbed, decreasing demand on HVAC systems. According to the White Roof Project, white coating reflects up to 90 percent of sunlight, compared to traditional black roofs that reflect only 20 percent. The organization also reports that summer energy use can be reduced by 10 to 40 percent with white roofs, which includes both coated roofs and white single-ply membrane installations.
Lawrence Berkeley National Laboratory, a U.S. Department of Energy National Laboratory, cites the following as other environmental benefits: lowering metropolitan air temperatures thereby mitigating the urban heat island effect, decreasing power plant emissions due to reduced air-conditioning demand, and slowed climate change.
It’s important to mention, though, that roofs coated white may increase heating energy demand in winter for geographies that experience cold winters. Oak Ridge National Laboratories and Lawrence Berkeley National Laboratory have carefully weighed the benefits against the winter heating penalty. This should be researched when considering roof coating.
Extending Roof Life
A roof coating can help you increase the time between reroofing projects. Ultraviolet and heat exposure cause chemical degradation of the roof membrane. Likewise, water accelerates deterioration. Coating can slow this process by providing an extra layer of protection to the surface of the roof. “White roofing prevents heat-related warping and cracking, extending the life of a roof,” reports the White Roof Project. Metal roofs, single-ply systems, modified bitumen, and built-up asphalt roofing can all be coated, as can spray polyurethane foam installations. The ideal time to apply roof coating is before the existing roof system starts to show deterioration.
Preventing Tear-Off Debris from the Landfill
According to the National Roofing Contractors Association (NRCA), more than 8 million tons of roofing tear-off waste is dumped into U.S. landfills each year. Extending the life of the roof means more infrequent need for tear-off. All coating manufacturers offer warranties, either material only or labor and materials, for between five and 25 years. If the original roofing system remains in good condition, recoating again is possible. Even recovering the roof system is feasible since coating systems are not considered a roof (most building codes prohibit recover when there is more than one existing roof system left in place due to load concerns).