Bronze Age and Iron Age Roundhouse

The roundhouse was the standard dwelling of Britain and Ireland from the Bronze Age through the Iron Age, and in some areas into the post-Roman period. Its defining feature is a conical roof over a circular wall of timber posts with wattle-and-daub panels, or of stone. Diameters ranged from under 5 m (16 ft) to over 15 m (49 ft). Circular houses with conical roofs also appear elsewhere in Europe, from the Villanovan huts of Italy to the palloza of northwest Spain, which has a conical rye-straw roof and no chimney.

Evidence

For most of the 20th century roundhouses were known almost entirely from rings of post holes, with only a few timbers preserved in bogs. Reconstruction depended on engineering judgement and experiment. The discovery at Must Farm in Cambridgeshire of Bronze Age roundhouses that had collapsed and charred with posts, walls and roofs in place confirmed much of what had been supposed.

Experimental archaeology

At Butser Ancient Farm in Hampshire, England, Peter Reynolds and his successors have built and monitored full-size roundhouses since the 1970s. Its Pimperne house, based on an excavated ground plan, was begun in 1976 and dismantled in 1990, and is one of the most fully recorded experiments:

• Plan: an outer ring of posts 12.8 m (42 ft) across and an inner ring about 9.75 m (32 ft) across.
• Walls: outer wall 1.52 m (5 ft) high; inner ring 3.04 m (10 ft).
• Roof frame: six principal rafters about 11.2 m (37 ft) long, arranged as a double tripod, each weighing 740-985 kg (1,630-2,170 lb); ring beams on the inner posts and about one-third of the way down from the apex; hazel purlins.
• Pitch: 45 degrees, which kept the house watertight.
• Thatch: about 7 tonnes of modern wheat straw. Laid at about one-third of the depth professional thatchers recommend, it lasted about ten years.

Experiments found that a pitch of around 45 degrees gave the strongest and most efficient design. The loads on the posts were essentially vertical, so the structure was stable once the post bases were packed.

Smoke and fire

Reynolds argued that roundhouses probably had no smoke hole at the apex, because the updraught would ignite the thatch. Instead smoke filled the roof space and seeped slowly out through the thatch. Modern reconstructions rest on such assumptions and may differ from the originals.

Reconstructions

Reconstructed roundhouses can be seen at Butser Ancient Farm, Castell Henllys in Pembrokeshire, Bostadh on Great Bernera (built 1999), Beeston Castle in Cheshire (a 2019 reconstruction of a house of about 2000 BCE), the Stonehenge Visitor Centre (Neolithic houses) and the Scottish Crannog Centre on Loch Tay.

Regional forms

In Atlantic Scotland the roundhouse developed into massive stone forms, including brochs and wheelhouses. In Ireland and Scotland roundhouses were also built on crannogs, artificial islands in lakes.