Metal Roofing Characteristics

Metal Roofing Characteristics

Material Advantages Drawbacks Incompatible Materials Longevity Thermal Expansion
Galvanized steel Least expensive. Strong and dent-resistant. Zinc coasting heals small cuts and scratches. Rusts after zinc wears away from oxidation. Field-cut edges vulnerable to corrosion. Brass, bronze, untreated iron and steel, redwood, cedar, pressure-treated (PT) lumber. Unpainted: 15-30 years. Exposed to salt spray: 5 to 10 years. 7.5
Aluminized steel Provides a true barrier to corrosion rather than sacrificial coating. Cuts and nicks not self-healing and prone to corrosion. Brass, bronze, lead, copper, wet mortar, redwood, cedar, PT lumber, graphite (e.g. penncil marks.) Unpainted: 20-40 years. 7.5
Galvalume Combines barrier protection of aluminum with healing characteristics of zinc. Reflects solar radiation. Field-cut edges vulnerable to tcorrosion in coastal areas. Lead, copper, unprotected steel, wet mortar, PT Lumber, and graphite. Unpainted: 30-40 years. 7.5
Aluminum Superior corrosion risistance. Lightweight. Good for coastal areas. Expensive. High Level of thermal expansion. Relitively soft. Low melting point. Brass, bronze, lead, copper, unprotected iron and steel, wet mortar, redwood, cedar, or PT lumber, and graphite. Unpainted: 30-40 years. 12.7
Copper Easily roll formed. Superior corrosion resistance. Attractive green patina. Very expensive. Greenish runoff can stain building. Avoid contact or runoff from cedar shingles. Aluminum, stainless steel, zinc, unprotected iron and steel, galvanized steel, lead, brass, bronze. 60+ years 8.8
Zinc Easily formed into intricate patterns. Superior corrosion resistance. Bluish-white patina. Very expensive. Runoff can stain building. Brass, bronze, copper, untreated iron and steel, stainless steel, redwood and cedar. 60+ years 15.1