In 2014 Leslie Cornell joined Cornwall Sustainable Building Trust – Charter 2020.
“CSBT Charterers have the common aim of making all areas of construction sustainable, by seeking the best environmentally sustainable option and sharing best practice and knowledge.”
As an experience practitioner of all aspects of Cob Construction, Leslie Cornell has completed many projects from small cob wall repairs to complete rebuild and new build cob walls.
This particular project was a great one. In early 2000 Leslie Cornell and his team had the opportunity to restore this ancient granite and cob barn in St Austell, Cornwall which was part of a complex of agricultural buildings. Before its sympathetic restoration, the great storm in 1987 had sealed its fate.
To achieve a successful and long-lasting repair a full understanding of the substrate and structure is required. Our initial question is, ‘What has caused the damage?’.
There are many reasons for varying states of disrepair – water penetration, failed cladding, failed roof timbers, bees, and subsidence. These, we have found, are the most common causes.
Deep hollows and rat runs, for example, can be quite easily and quickly repaired with the use of pre-formed cob bricks and/or blocks.
There are many hundreds of buildings and boundary walls constructed with cob in Cornwall.
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.
Cob is a mixture of subsoil, straw and water. When these elements are combined together they can be used in various ways for building.
To achieve a successful building medium, the soil must be free of large stones and must have clay content as this, once dried, will harden and give the wall its strength. Straw is as important as the stalks will bind the soil together.
Barley straw is the most commonly used binder in the production of cob in Cornwall and the South West of England.