There are three standard types: Type I, uniform or nonuniform thickness; Type II, thick butt; and Type III, uniform or nonuniform thickness (ASTM D225). Average weights must be 95 lb per square (100 ft2). For types I and III, the weather-side coating must weigh 23.0 lb per square; for Type II, 30.0 lb per square. The material in these shingles is similar to that in granule-surfaced roll roofing.
