What is better, Coatings or Aggregate Ballast?
SPF roofs can be protected from ultraviolet light with coatings — typically acrylic, polyurethane, or silicone coatings — or with crushed stone aggregate. Aggregate-covered roofs, sometimes called “foam and stone,” require stone ranging in size from 1/4 inch to 3/4 inch Gravel can only be used on relatively flat roofs, and its weight may exceed structural limits. Coated foam weighs only 1/3 pound per square foot, while aggregate-covered foam is closer to 6 pounds per square foot. Coated foam makes it easier to spot and repair a roof leak. Gravel maintenance is more difficult, because you can’t see what’s under it. Gravel can stop up drains. The reflectivity values of coatings are known, coatings (unlike gravel) are eligible to receive an Energy Star label Coatings usually cost a little more than stone. Coating on an SPF roof will last anywhere from 10 to 15 years.
