Durability of light steel framing in residential applications

This paper presents a summary and analysis of research findings on the durability of galvanised cold-formed steel sections used in housing in order to deduce their design life. These cold-formed sections are produced from pre-galvanised strip steel. It reviews reports and publications from research projects carried out by Corus and the Steel Construction Institute on zinc-coated, cold-formed steel products. New data have also been gathered from measurements on houses and similar buildings that have used galvanised steel components. The data also extend to over-cladding applications in building renovation. The performance of galvanised (zinc-coated) steel components within warm-frame applications is very good. The research leading to this paper shows that the predicted design life of the standard G275 coating, based on the measured loss of zinc from the strip steel, is over 200 years, provided that the building envelope is well insulated and properly maintained. The evidence for this conclusion is based on measurement of zinc loss on light steel frames in various applications and locations. A formula for the loss of zinc over time in areas subject to low condensation risk is presented.