Technical Bulletin #93 : Galvalume and Galvanized Steel

Angie's List Reviews
Click here for BBB Business Review
Get your free copy of An Insider’s Guide to Metal Roofing. Click here.
To set up an appointment for a free estimate click here.

ISSUE

Metal roofing panels are available in a variety of metals including steel, aluminum, copper, and zinc. While exotic steels such as stainless are sometimes used, the steels more commonly used in roofing are galvanized and galvalume. In considering a metal roof, it is important to understand the differences between these two types of steel.

ANALYSIS

Galvanized steel is carbon steel with a metallic coating of primarily zinc on its surface. Galvalume is carbon steel with a metallic coating or primarily aluminum on its surface. There is no problem with electrolysis between dissimilar metals because the metallic coating is a continuous coating with no ability for a catalyst to get between it and the carbon steel to prompt corrosion. With both galvanized and galvalume, various thicknesses of the metallic coatings are available. Galvanized is commonly G90 grade while galvalume is commonly AZ55 grade. One generally accepted attribute of galvalume is that the aluminum metallic coating provides greater corrosion resistance than does the zinc coating of galvanized. However, for metal roof profiles which have substantial forming and tight bends in the metal, the zinc of galvanized can have a better “bridging” effect to create superior corrosion resistance over the tight folds and bends.

Classic Products, Inc.


Return to Technical Bulletins page

Classic Metal Roofs, LLC -- lifetime residential metal roofing. \'The best roofs under the sun.\' Located in and serving southern New England.

Classic Metal Roofs, LLC,
Serving Massachusetts, Rhode Island, Connecticut, and southern New Hampshire
Toll free: 866-660-6668
Classic Metal Roofs, LLC Classic Metal Roofs, LLC Classic Metal Roofs, LLC Classic Metal Roofs, LLC
E-mail Us HerePrivacy PolicyTerms of Service