What Is Galvanized Metal?
The galvanized coating process, where carbon steel is dipped in molten zinc, has been around for hundreds of years and results in a long lasting material. Galvanized metal is a steel that is coated with rust-inhibiting zinc that protects the steel core from corrosion. The thicker the layer of zinc, the longer you have before it corrodes away and exposes the steel substrate.
Galvanized roofing is offered in three common levels of protection: G40, G60, and G90. Most metal roofing panels that have a galvanized finish are a G90 galvanized coating. The higher the number, the thicker the zinc coating. Therefore, G90 is a thicker metal panel and offers more protection to the metal panel than G40 and G60.