Asphalt shingles are composed of: a base material, either organic felt or glass-fiber mat, that provides support for the weather-resistant components and gives a shingle strength; asphalt and fillers; and surfacing material, generally in the form of mineral granules, that provides protection from impact and UV degradation and improves fire resistance.
Shingles may be produced in a single layer or two or more layers. The latter generally are known as laminated strip shingles, or architectural shingles, and they have a three dimensional appearance.
Both 3-tab asphalt shingles and laminated asphalt shingles contain a strip of factory applied adhesive that is activated by the sun’s heat after installation and seals each shingle to the next course. The seal strip also provides much of a shingle’s resistance to wind uplift. Shingles with factory-applied adhesive have a strip of clear polyester film applied to each shingle to prevent the sealing strips from bonding the shingles together when packaged. When the shingles are installed, the self-sealing strips will not align with the plastic film strips and will bond to adjacent shingles. For this reason, the plastic film strips do not have to be removed.