| 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 |
