July 26, 2006—According to the White Coatings Council of the Roof Coatings Manufacturers Association (RCMA), white coatings can extend the life expectancy of many different types of commercial roofing systems simply by avoiding the high roof temperatures associated with exposure to the sun.
The technical term for exposure is “insolation,” and it is measured in terms of the rate of solar radiation received per unit area (typically expressed in watts per square meter). Under very clear skies, up to 1220 w/m2 of solar radiation reaches the rooftop. Heavily insulated roof systems block this heat from penetrating the building as heat; however, in summer months, convective heat transfer to the surrounding air and radiant heat transfer are inefficient. Consequently, the heat has nowhere to go and roofing membrane temperatures can soar.
For commercial roofing systems made from organic materials, high temperatures can shorten the life of the roofing system, says the Council. As temperatures rise to the peak of this range, degradation of roofing systems increases exponentially. A rule of thumb for thermal aging is that service life is cut in half for every 10 °C (18 °F) increase in temperature.
The Roof Coatings Manufacturers Association is the national trade association representing the manufacturers of cold-applied protective roof coatings and cements, and the suppliers of products, equipment, and/or services to and for the industry. For more information, visit the RCMA Web site.
