Roof system types and materials are divided into two (2) general classifications: low-slope and steep-slope.

Low-slope roofing consists of materials and systems that are impermeable to water or weatherproofed and are typically installed on slopes less than 3:12 (14 degrees).

Steep-slope roofing consists of materials and systems that are considered “watershedding” such as shingles and are generally installed on slopes exceeding 3:12 (14 degrees).