Invention of Corrugated Iron (1829)

Corrugated iron was invented in London in the late 1820s. In 1829, Henry Robinson Palmer, architect and engineer to the London Dock Company, was granted a patent for "indented or corrugated metallic sheets". Bending thin metal into a wave profile made it far stiffer than a flat sheet of the same weight, so it could span between widely spaced supports, or even form a self-supporting arch.

The first buildings

Palmer saw the material as suited to wide-span roofs. In 1830 he built a shed at the London docks with a span of about 12 m (40 ft), roofed entirely in self-supporting corrugated iron. A contemporary account praised it as the lightest and strongest roof, for its weight, ever made. Early railway and dockyard roofs followed, including at Chatham Dockyard and Liverpool Lime Street station.

Material and protection

The first sheets were wrought iron produced by puddling. Plain iron rusts quickly, so galvanising, coating the iron with zinc, became essential. British sources say galvanising was perfected soon after corrugated iron appeared, and the combination became known as corrugated galvanised iron (CGI). Sources do not agree on a precise date for the first galvanised corrugated sheet.

After the patent

Palmer's patent expired in 1843. With no monopoly, manufacturers multiplied and corrugated iron became a worldwide roofing material. From the 1890s mild steel gradually replaced wrought iron, but the name "corrugated iron" stuck.

Typical early sheets

Historic British sheets were usually 0.9-3 m (3-10 ft) long with a corrugation pitch of about 75-125 mm (3-5 in). Roofing sheets were commonly 18 Standard Wire Gauge, about 1.2 mm (0.048 in) thick, considerably heavier than most modern sheet.

Significance

The invention made it possible to roof large spaces cheaply with a light, prefabricated, easily shipped product. Within two decades it was being exported in prefabricated buildings to Australia, Africa and beyond.