Corrugated galvanised iron, commonly abbreviated CGI, is a building material composed of sheets of hot-dip galvanised mild steel cold-rolled to have a linear corrugated pattern in them. The corrugations increase the bending strength of the sheet in the direction parallel to the corrugations, but not across them. Normally each sheet is manufactured longest in its strong direction. Look up abbreviation in Wiktionary, the free dictionary Abbreviation (from Latin brevis short) is strictly a shortening, but more particularly, an abbreviation is a letter or group of letters, taken from a word or words, and employed to represent them for the sake of brevity. ... Building material is any material which is used for a construction purpose. ... Hot-dip galvanizing is the process of coating iron or steel with a thin zinc layer by passing the steel through a molten bath of zinc at a temperature of around 450°C. Zinc rusts to form zinc oxide, a fairly strong material that stops further rusting, protecting the steel... Steel is a metal alloy whose major component is iron, with carbon being the primary alloying material. ...

CGI is lightweight and easily transported. It has and still is widely used especially in rural and military buildings such as sheds and water tanks.

Pitch and depth

The corrugations are described in terms of pitch (the distance between two crests) and depth (the height from the top of a crest to the bottom of a trough). It is important for the pitch and depth to be quite uniform, in order for the sheets to be easily stackable for transport, and to overlap neatly when making a join. Pitches have ranged from 25 mm (1 inch) to 125 mm (5 inches). It was once common for CGI used for vertical walls to have a shorter pitch and depth than roofing CGI. This shorter pitched material was sometimes called "rippled" instead of "corrugated". However nowadays, nearly all CGI produced has the same pitch of 3 inches (76 mm). A millimetre (American spelling: millimeter), symbol mm is an SI unit of length that is equal to one thousandth of a metre. ... Mid-19th century tool for converting between different standards of the inch An inch is an Imperial and U.S. customary unit of length. ...

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. Galvanization, named after the Italian scientist Luigi Galvani, was originally the administration of electric shocks (in the 19th century also termed Faradism, after Michael Faraday). ...

History

CGI was invented in the 1840s, and 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 and Australia and later India, and in Australia also became (and remains) the most common roofing material even in urban areas (in which application it is usually painted). For roofing purposes, the sheets are laid somewhat like tiles, with a lateral overlap of two or three 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. Events and Trends Technology First use of anaesthesia in an operation, by Crawford Long War, peace and politics First signing of the Treaty of Waitangi (Te Tiriti o Waitangi) on February 6, 1840 at Waitangi New Zealand. ... Wrought iron is a very pure form of commercial iron, having a very small carbon content. ... Corrosion Corrosion is deterioration of useful properties in a material due to reactions with its environment. ... This article needs to be cleaned up to conform to a higher standard of quality. ... For information on the U.S. borough, see Paint, Pennsylvania. ... MM or Mm or mm can stand for: A millimetre (mm) or megametre (Mm) Initials of Marilyn Monroe Macromedia Morning Musume Roman numeral for 2,000 and the year 2000 Myanmar Master of Management Maelzels metronome: precedes a beats-per-minute tempo measurement Maximum Medicine Moderna Misstag, Swedish Quake_2...

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. Galvanised sheets with simple corrugations are also being gradually displaced by zincalume or powder-coated sheets with complex profiles. However CGI remains common. The 1890s were sometimes referred to as the Mauve Decade, because William Henry Perkins aniline dye allowed the widespread use of that colour in fashion, and also as the Gay Nineties, under the then-current usage of the word gay which referred simply to merriment and frivolity, with no...

External links

• Heritage Roofing in Victoria, Australia (PDF, 181 kB)

See also

• Nissen hut