A good hat
When I give talks about building materials or vernacular architecture, this picture sometimes elicits a gasp of amazement. A field wall, made of cob (here a mix mainly of mud and chalk I think) and roofed with thatch. Such a thing seems eccentric these days. People think cob must be an ephemeral material – but it can last a lifetime with the proper protection, given, in the old phrase, ‘a good hat and a good pair of shoes’. The hat is provided by tiles or thatch. But thatching is a skilled trade and roofing a wall like this takes a lot of effort and expertise: it must be a costly process. In past centuries, though, the cost of materials and transport could be a larger proportion of the total bill of a typical building project, and both time and labour could be cheaper than they are now. In the Middle Ages, if stone was not plentiful, mud and thatch could at least reduce the cost of the materials.
And yet, clearly, people who could afford to buy stone and bring it to the site also just liked the idea or the look of an earth wall. In c. 1320 at Lambeth Palace, London home of the Archbishop of Canterbury (who could have had stone for the asking), six perches† of garden wall were repaired and rethatched with reeds. Mud or cob walls for fields and gardens are not so common now, but you still find them in some places. I’ve come across them in Northamptonshire, for example. Chalk areas (parts of Wiltshire and Buckinghamshire, for example) also have chalk walls, similarly thatched. I hope people still like them enough to make the effort to maintain them.
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*Cob: a building material made from mixing earth and straw. Lime may be added and in some areas the cob can contain a large proportion of chalk. In Buckinghamshire, especially in the Haddenham area, chalk cob is known as wychert; in Cornwall cob is also referred to as clob.
† A rod, pole, or perch: an old measurement equivalent to 161/2 feet – just over 5 metres; so six perches would be a good 30 metres: quite a bit of wall.
