Our 2006/07 survey revealed several large clusters, indicating the prolific use of cob around the county. As well as these clusters of cob buildings, small groups and isolated one offs, were also unveiled.
This information was transposed to a geological map of Cornwall and tallied with the allochtonous substrate. Shuttering was used where door openings were required.
Lintels for windows would be buried in the cob at the appropriate height and the cob would be removed below each lintel at a later stage.
There is some evidence to suggest that the size of the window opening, or even having a window at all, depended on affordability, availability or even the window taxation period during the 1700’s.
We discovered oak lintels buried in the wall on three separate projects, supporting the theory that the luxury of a window was not always possible.
Nowadays, when cob is required in large quantities mechanical assistance is used.
The soil, straw and water are distributed on a hard surface and a tractor or digger (the bigger the wheels the better) is driven back and forth over the ingredients.
Cob is only successful when mixed by compaction. The bucket on the vehicle is used to ‘turn’ the mixture and ultimately to pick it up and take it to the wall head.
Small amounts of cob can be trampled by human feet and used just as effectively for repairs.
Pic 6, Pic 7