A true design classic, like the Mini or the VW Beetle, the basic concept of the roundhouse was hard to better. A low roughly circular wall with a gap for the doorway topped by a high, conical thatched roof is the norm. There are variations in size and the construction of the walls and thatch usually reflect the materials readily available on site. The framework of the roundhouse makes this sort of customisation easy to accommodate.
The roundhouse is found first in the later third millennium BC in southwest Scotland. At this point in the Bronze Age, people lived in upland areas and some roundhouses are found more than 400m above sea level. By the end of the Bronze Age, there was an increase in lowland agriculture, more people were living together and the roundhouses of the time reflect this in size and location. They approach 10m in diameter in some cases and their numbers increase, especially along river valleys. There has been a lot of emphasis on the early Iron Age roundhouses of Wessex. The larger examples were thought to be the residences of Iron Age chieftains and Gerhard Bersu, in the 1930s, claimed a diameter of 25m for some houses on the Isle of Man. However most examples from this era range between 4 and 14m in diameter.
The typical roundhouse would sleep an extended family of 12-20 people; with organic beds at the house rear. All light came from the wide doorway. The only significance in the alignment of the doorway would have been to maximise the amount of light in the house. Daily activities, such as food preparation and craft-working, took place at the house front in the day and around the hearth at night. The usual central position for the hearth not only ensured an even distribution of heat and light but helped to minimise fire risk. There was no hole at the roof apex and the smoke simply filtered out through the thatch.
Houses were generally kept clean and the more we learn about prehistory the more we realise that many finds excavated from houses were actually deliberately deposited by the occupants. Foundation deposits, which are popular in the Bronze Age, often involved placing quern-stones in house walls. At Green Knowe (Peebleshire) the deposited quern had never been used. Household deposition increases at the end of the Bronze Age, mirroring the deposition of bronze in rivers and bogs. In the Iron Age, quern-stones are often found inverted in drainage gullies. In the Roman Iron Age, abandonment deposits are very popular; particularly the placing of broken jewellery on house floors. Deliberate breaking of objects, even heavy querns, is very common in prehistory.
The houses that we excavate were abandoned by those who had lived in them. We can tell that this was usually a planned process and people took their belongings with them to their new home. Not much is left for us to find in the 21st century. Destruction by fire was rare and more normally it seems that houses were allowed to collapse and decay naturally, with refuse collecting on some old house sites.
The roundhouse remained the dwelling of choice through the Iron Age and throughout the Roman period though they are smaller at this time; up to 5m in diameter. This is probably because they tended to have stone walls which, actually, are not as strong as timber!
This is where the style of building changes. Rectangular buildings replace the roundhouse eventually because of construction materials and, possibly, because of the Roman influence; the arrival of concrete, the arch and the rectilinear layout.