A Nissen hut is a prefabricated steel structure originally for military use, especially as barracks, made from a 210° portion of a cylindrical skin of corrugated iron. It was designed during the First World War by the Canadian-American-British engineer and inventor Major Peter Norman Nissen. It was used also extensively during the Second World War and was adapted as the similar Quonset hut in the United States.

Corrugated galvanised iron (CGI) or steel, colloquially corrugated iron, wriggly tin, pailing, corrugated sheet metal, zinc or custom orb / corro sheet (Australia) is a building material composed of sheets of hot-dip galvanised mild steel, cold-rolled to produce a linear ridged pattern in them. Although it is still popularly called "iron" in the UK, the material used is actually steel, and only the surviving vintage sheets may actually be made up of 100% iron. The corrugations increase the bending strength of the sheet in the direction perpendicular to the corrugations, but not parallel to them, because the steel must be stretched to bend perpendicular to the corrugations. Normally each sheet is manufactured longer in its strong direction.