History
CGI was invented in the 1820s in Britain by Henry Palmer, architect and engineer to the London Dock Company. It was originally made (as the name suggests) from wrought iron. It proved to be light, strong, corrosion-resistant, and easily transported, and particularly lent itself to prefabricated structures and improvisation by semi-skilled workers. It soon became a common construction material in rural areas in the United States, Chile, New Zealand and Australia and later India, and in Australia and Chile also became (and remains) the most common roofing material even in urban areas. In Australia and New Zealand particularly it has become part of the cultural identity, and fashionable architectural use has become common.
For roofing purposes, the sheets are laid somewhat like tiles, with a lateral overlap of one and half corrugations, and a vertical overlap of about 150 mm, to provide for waterproofing. CGI is also a common construction material for industrial buildings throughout the world.
Wrought iron CGI was gradually replaced by mild steel from around the 1890s, and iron CGI is no longer obtainable - however, the common name has not been changed. Galvanized sheets with simple corrugations are also being gradually displaced by 55% Al-Zn coated steel or coil-painted sheets with complex profiles. However CGI remains common.
Read more about this topic: Corrugated Galvanised Iron
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