After its invention in London in 1829 and the expiry of the original patent in 1843, corrugated galvanised iron (CGI) became one of the most widely used roofing materials in the world. It was light, strong, easy to ship flat, simple to fix with basic tools and fireproof. These qualities made it the material of frontiers, colonies, mining camps and, later, informal settlements.
Prefabricated buildings for export
By the 1840s British firms were making fully prefabricated iron buildings, many shipped to colonies, notably Australia and South Africa. In 1845 an "iron palace" made in Liverpool for export to Africa was put on public display before shipment. Firms supplied iron churches, chapels and schools in large numbers; in Britain these became known as "tin tabernacles". Some bishops are said to have refused to consecrate iron churches.
Settler countries
CGI became common in rural areas of the United States, Argentina, Spain, New Zealand and Australia, and later India. In Australia and Argentina it remains a common roof even in cities. Australians call the classic profile "custom orb" or "corro".
Africa, the Caribbean and the tropics
CGI also became a familiar roof across Africa, the Caribbean and India. Local names reflect how familiar it became: in Nigeria and Cyprus it is often simply called "zinc", and in Caribbean English "pailing". Today it is widely used in informal settlements in Africa and elsewhere.
War and status
In Britain CGI replaced thatch on many rural buildings between the late 19th and early 20th centuries. The First World War Nissen hut, named after Captain Peter Nissen, and the Second World War Anderson shelter, of which at least 1.5 million were distributed, gave it a utilitarian, temporary image. Mid-20th-century architects later used it deliberately for its industrial character.
Modern successors
Plain galvanised sheet is gradually giving way to steel coated with a 55% aluminium-zinc alloy and to pre-painted sheet with more complex profiles, but traditional corrugated sheets are still produced worldwide.
Sources
- Corrugated Iron ArchitectureThe Building Conservation Directory · buildingconservation.com
- Corrugated galvanised ironWikipedia · en.wikipedia.org
- Metal roofWikipedia · en.wikipedia.org