What are Asphalt shingles?
Asphalt is one of the primary ingredients in roofing shingles. Its purpose is to provide the waterproofing integrity for the roof. Secondarily, the asphalt holds the colored granules in place and contributes to the overall strength of the shingle. Asphalt, which is derived from petroleum, contains the oils that provide ductility and pliability to the shingles. During the lifetime of the shingles these oils begin to rise to the surface, where they are washed away by rainwater. In an attempt to restore equilibrium, new oils surface and the washing process continues. Also, the intense heat of the roof oxidizes or hardens the asphalt over time.