How do I decide whether G-60 or G-90 galvanized finish is appropriate when using cold-formed steel framing in a commercial application?
The AISI Standard for Cold-Formed Steel Framing – General Provisions requires a minimum metallic coating complying with the requirements of ASTM A1003, which in turn stipulates a minimum G-60 for structural and G-40 for non-structural framing members. The General Provisions further stipulates, “Unless additional corrosion protection is provided, framing members shall be located within the building envelope and adequately shielded from direct contact with moisture from the ground or the outdoor climate.” There is no further specification document that provides guidance. However, as long as the framing is located within the building envelope and the building is not located less than 300 feet from a shoreline (3000 feet in the case of framing located in a ventilated attic or crawl space), the standard G-60 coating should be adequate. For additional information, the CFSEI has developed a Tech Note on this subject.
