Existing Cob Buildings

Cob, being relatively common in the South West, is frequently encountered when dealing with existing buildings.  However, until very recently, there has not been any concerted effort to understand this material or find methods and techniques for repairing or maintaining cob.  Repairs had been and in some cases are still carried out in an ad hoc manner using modern and unsuitable building materials which can often lead to serious problems occurring later.  The most notable example of the inappropriate use of modern materials is the coating of walls with cement-based plasters and renders.  These materials tend to trap moisture in the wall construction so that it builds up to the point that the cob becomes saturated, softens and eventually fails leading to the collapse of the wall.  This has occurred and is still occurring on a regular basis.  If your building is coated with impervious cement-based materials or has been subjected to tanking, it should be closely looked at and monitored to ensure that these problems are not manifesting themselves.  

Dealing with similar problems on cob properties and becoming the owner of a part cob building that required extensive renovation, Barry Honeysett started to look more seriously at this material and how to respond to it.  At roughly the same time, extensive repair work was being carried out on a cob-built medieval manor known as Bowhill, Exeter, owned by English Heritage.  This project allowed English Heritage to experiment with methods of repairs and reconstruction of the cob walls.  Also at a similar period in the early 1990s, the Devon Earth Building Association (DEBA) was formed by people with an interest in cob buildings.  Along with other members of the Association, a deeper understanding of this material and how it should be cared for has been developed.

Barry Honeysett now regularly presents seminars and talks on the diagnosis of structural problems in cob buildings and the methods of repair at places such as Plymouth University as part of their Building Conservation course.  We are regularly asked to provide assistance on cob buildings by homeowners who notice cracking appearing in the render or plaster or when alterations are carried out to cob buildings which sometimes reveal past defects.  We have developed a range of methods for repairing structural defects in cob walls such as cracks, damp-affected cob, erosion and voids within the wall (which are often created by rats).  We will as far as possible look at the building as a whole as there are often outside influences that are affecting the cob walls.  For example, a spreading roof truss could be pushing the walls outwards and causing them to crack at the junctions.  It is often a matter of carrying out a detailed inspection of the other elements of the building before providing a diagnosis and our recommendations for any remedial works.  Please do contact us if you think you have a problem with your cob building as we are always happy to give advice and discuss any concerns you may have.