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While more expensive than asphalt, metal roofing lasts longer and is more wind resistant. 1  Materials: May be composed of steel, aluminum, copper, or zinc alloy. 2  Steel roofs come with either a zinc coating or painted finish. 3  Copper roofs are installed unfinished and acquire a protective green patina with age.
Roof system types. Roof systems and materials generally are divided into generic classifications: low slope and steep slope. Low slope roofing includes water impermeable, or weatherproof, types of roof membranes installed on slopes less than or equal to 3:12 (14 degrees). Steep slope roofing includes watershedding types of roof coverings installed on slopes exceeding 3:12 (14 degrees). Low-slope roofing.