How can steel defend against corrosion?

Steel frames are made of steel protected against corrosion by a hot-dipped metallic coating of either a zinc-aluminium alloy, or almost pure zinc (galvanised). These coatings conform to the appropriate Australian standards or their equivalent. In external applications such as roofing these products are exposed to the elements and have excellent durability, so in less exposed applications such as inside the building envelope they weather more slowly. Where there are drill holes and cut edges the galvanic action, or sacrificial protection, of the coatings protects the exposed steel edge against corrosion.