Nissen Hut - Description

Description

A Nissen hut is made from a sheet of metal bent into half a cylinder and planted in the ground with its axis horizontal. The cross-section was not precisely semi-circular, as the bottom of the hut curved in slightly. The exterior was formed from curved corrugated steel sheets 10 feet 6 inches by 2 feet 2 inches (3.2 × 0.7 m), laid with a two-corrugation lap at the side and a 6 inch (15 cm) overlap at the ends. Three sheets covered the arc of the hut (about 54 sheets in all were required). These were attached to five 3 × 2 inch (7.5 x 5 cm) wooden purlins and 3 × 2 inch wooden spiking plates at the ends of the floor joists.

The purlins were attached to eight T-shaped ribs (1¾ × 1¾ × ⅛ inch; 4.5 × 4.5 × 0.5 cm) set at 6 feet 0.5 inch (1.8 m) centres. Each rib consisted of three sections bolted together using splice plates, and each end was bolted to the floor at the bearers. With each rib were two straining wires, one on each side and a straining ratchet (or in some cases a simple fencing wire strainer). The wires were strained during construction. The straining wires do not appear in the original Nissen patent.

The purlins were attached to the ribs using a "hook" bolt, which hooked through a pre-drilled hole in the rib and was secured into the purlin. The hook bolt was a unique feature of the Nissen design.

Interior lining could be horizontal corrugated iron or material like Masonite attached to the ribs. Sometimes corrugated asbestos cement sheeting was used. The roof and lining form a circular space with a radius of 8 feet 0.5 inch (2.4 m), although, because of the inward curve, the floor was only 15 feet 10 inches (4.8 m). The space between the interior and exterior lining could be used for insulation and services, if required.

The walls and floors rested on foundations consisting of 4 × 4 inch (10 × 10 cm) stumps with 15 × 9 inch (38 × 23 cm) sole plates. On these were 4 × 3 inch (10 × 8 cm) bearers and 4 × 2 inch (10 × 5 cm) joists at 2 feet 10 inch (1 m) centres. The floor was made from tongue and groove floorboards. At East Hills and at Villawood the floor was concrete; the ribs in this case were simply attached to the concrete slab by a metal strap.

At either end the walls were made from a wooden frame with weatherboards nailed to the outside.

Windows and doors could be added to the sides by creating a dormer form by adding a frame to take the upper piece of corrugated iron and replacing the lower piece with a suitable frame for a door or window.

Nissen huts come in three internal spans — 16 ft (4.9 m), 24 ft (7.3 m) or 30 ft (9.2 m). The longitudinal bays come in multiples of 6 ft (1.83 m). The corrugated steel half-circles used to build Nissen huts can be stored efficiently, because the curved sheets can be cupped one inside another.

However, there was no standard model of Nissen huts, as the design was never static but changed according to demand.