Corrugated iron is a building material made by taking sheet iron or steel and pressing it into corrugations to give the flat sheet stiffness without the need for a frame.
By eliminating a frame, nails and their holes are also eliminated, so that the corrugated iron remains waterproof. The sheets are usually galvanised to prevent the iron from rusting.
Small sheets can be combined into larger sheets by overlapping one or more corrugations. These overlaps need not be nailed, again avoiding holes that causes water leakage problems.
Corrugated iron is lightweight and easily transported. It has and still is widely used especially in rural and military buildings such as sheds and water tanks.
History
Corrugated iron first appeared with the Industrial Revolution of the 19th Century. It was particular useful as a building material where local timber was in short supply, such as the plains of middle America.
See also