No house can be considered more warm and cozy than that built of Cob, especially when thatched. It is warm in winter and cool in summer, and I have known workers to bitterly bewail their fate in being transferred from an old 15th or 16th century Cob cottage to a newly built edifice of the most approved style, as they said it was like going out of warm life into a cold grave.
From “Book of the West” by S. Baring-Gould
What is Cob?
Cob is a form of traditional earthbuilding that uses a mix of decomposed shale, chopped straw, clay and water to build durable walls that moderate a building’s interior temperatures.
Cob was once the cottage material of choice in Devonshire, South Wales and the west of England.
Many Devon Cob houses are 200 to 300 years old with some dating to the 1500’s, with walls four feet thick. The composition of the Cob varies with local conditions.
Cob is turned on the ground with a tractor. It goes up in “perches”. Each perch is roughly 16 1/2 feet long and 12” high. Perches are created by laying loaf-sized “cobs” onto the wall in a diagonal pattern whih are then “thumbed in”.
After curing, the walls are smoothed with lime and/or clay plasters. (Adapted from “The Earthbuilder´s Encyclopedia” by Joe Tibbets).
Sheltercraft is currently developing a cob module that can be quickly assembled into panels on-site. In the meantime, we still use semi-traditional methods to build cob walls.