Galvanized panels are a very popular substrate for metal roofing. Manufacturers often use terms such as G60 or G90 to describe their products. What’s the difference? And which should contractors use in various applications?
Galvanization is the process of applying a protective zinc coating to steel or iron, to prevent rusting. After roofing panels are galvanized, they can be painted or granular-coated. The grades of galvanized products correspond directly to anticipated field longevity. With galvanized substrates, the more zinc the better. These “G” numbers indicate how many ounces of zinc are applied to each 100 sq. feet of paneling. G60 has 60 ounces, G90 has 90 ounces and therefore provides better corrosion resistance. These numbers are directly related to increased longevity and long-term aesthetics for the roof.
The Metal Construction Association has developed a Guide Specification for Residential Metal Roofing that clearly defines which galvanized products should be used on homes. All MRA members must agree to adhere to or exceed the MCA’s Guide Specification for Residential Metal Roofing before they are permitted to join the association. This same rule applies for both manufacturers and contractors. For galvanized steel used in residential applications, the MRA recommends a minimum metallic coating of G-90. So, if you’re not sure of the coating of the panels you are installing on homes, it’s in your best interest to find out. Again, the higher the number, the better protection from rust.
Why It Matters
“Members of the metal roofing industry are constantly fighting the outdated ‘rusty barn roof’ image, and the Metal Roofing Alliance has made great progress in educating consumers about today’s beautiful, long-lasting metal roofing options. Every bad roof installation is a step in the wrong direction,” says MRA’s Executive Director Bill Hippard.
In a competitive environment, it may be tempting to choose a lower quality (and therefore lower cost) steel panel when installing a new metal roof. However, for roofers who are looking to build a business and remain in this growing residential market segment, that choice offers short term gain in exchange for long-term pain. Whenever a lower-quality metal roof is installed, it’s almost certainly doomed for failure, resulting in customer complaints and a damaged reputation for all metal roofs.
Former customers are an excellent referral source, and a happy homeowner will recommend your business to their friends and neighbors. The opposite is also true – install an inferior product, and you will hear about it as well as those same friends, neighbors and perhaps even the local licensing authorities.