Reflective roof coatings are available in two basic types. One type is a white roof coating, usually water-based acrylic. White roof coatings usually give lower roof temperatures than aluminum coatings, but there are other factors to consider when purchasing a reflective coating. The type of coating a manager specifies depends on the type of roof on the building, and of course, appearance. Metal roofs can be coated with either the aluminum or white coating, but they often are coated with asphalt-aluminum roof coating to retain the metal look.
Asphalt acts to prevent rust, which is another reason it is used on metal roofs.
Some white roof coatings contain a rust preventative, but managers should read the label or contact the manufacturer if inhibiting rust is an essential function of a desired coating. Roofs made of asphalt are common on low-sloped areas. They are also quite common on commercial and institutional facilities. The black or brown asphalt roof retains a great deal of heat. These roofs usually have the asphalt-aluminum coating, as the two products are very compatible.