Galvanised corrugated steel sheets have been around for a very long time and are a very strong and secure roofing and cladding material. These are often used by emergency repair companies to temporarily secure properties before permanent repairs are made.
The steel sheet is coated in zinc, which is more reactive to oxygen than the iron and causes a white oxidisation coating to take place. Once all the zinc has been used up in this type of reaction then the iron in the steel will react and this is when the sheets will rust. These sheets are primarily used as a temporary covering, but to increase their lifespan they should be coated / painted to provide a barrier between the steel and the oxygen.
Please note. NOT COMPATIBLE WITH 3" PVC ASBESTOS PROFILE CORRUGATED SHEETS, USE THE POLYCARBONATE CORRUGATED