What is “Galvalume” versus galvanized steel?
Various metallic coatings for steel sheet are available for use in the metal building industry. These coatings are either zinc, aluminum, or an aluminum-zinc alloy. The aluminum-zinc alloys are referred to by the percent of aluminum present in the coating by weight. Galvalume is a trademark for a steel roofing product that is 55% Aluminum-Zinc alloy coated. It is also manufactured and sold under the trademark Zincalume. ASTM A792 is the specification covering sheet steel coated by this process. The coating designation refers to the weight, e.g. AZ55 is 0.55 oz/ft2, total for both sides. Galvanized products, on the other hand, utilize a zinc coating. ASTM A653 is the specification covering galvanized steel sheets. The coating designation for galvanized products also refers to the weight, e.g. G90 is 0.90 oz/ft2, total for both sides. Aluminum-coated steel sheet is covered by ASTM A463. General requirements for all of the steel sheet products that are metallic-coated by the hot-dip proce
