Granules

Granules are defined as the ceramic-coated crusite minerals or manufactured mineral particles embedded in the surface of asphalt shingles to protect the underlying asphalt from UV radiation, provide fire resistance, and add color. A single architectural shingle contains approximately 1,500 to 2,000 granules per square inch. Granule loss is a primary indicator of shingle aging; significant granule accumulation in gutters typically signals that shingles are nearing the end of their serviceable life.