Keppel Gate

May 8th

Channel 5

8pm

!New build cob workshop, saturday 7th June 2008, mob- 07976241553! We are a small company established in East Devon with over 20 years experience specializing in the high quality repair of historic buildings particularly those containing cob and increasingly in recent years the construction of new buildings. Anything from garden walls, summer houses to extensions and complete new houses using cob as the main walling material where appropriate to create beautiful buildings out of local materials which are healthy to live in and blend naturally with their environment. The reason for setting up this web site is to encourage those who may be thinking of carrying out some building project to consider the merits of using cob, which despite the fact that it has been used in the west country for at least one thousand years, is not widely understood. What is cob? Cob is a mixture of sub-soil which must contain some clay and straw (usually wheat or barley). The amount of clay will vary from site to site depending on local sub-soil make up, it is sometimes worth adjusting the balance of aggregates to reduce shrinkage and increase weather resistance and compressive strength in the final mix. Approximately one third of the world’s population live in earth buildings of one sort or another. Cob is unusual as an earth building technique in that it is a monolithic structure, which is built without shuttering. The straw is used to hold the mix together in its early wet and very plastic state, in this way after a short drying period in can be pared down to the required shape and form. This is done either with a sharp spade or mattock then the surface is dressed up with a heavy mallet and can even be finished with the bare hand. Thus creating a hand-sculptured building with wonderful possibilities for pleasing form. Why use cob? As well as the important aesthetic of form, colour and texture and an automatic blending with the local environment (as long as your sub-soil is locally sourced). Cob has several other important characteristics, firstly walls are usually very thick, typically 2-3 feet and this, as well as being very good insulation against heat and cold is a massive heat store. So there is a fly-wheel effect on thermal movement. In other words, cool nights and warm days are evened out as well as when doors and windows are left open resulting in a change and cooling of the air in a building. As soon as they are closed the building warms up again through the heat stored in the thermal mass of the walls. This means that typically a cob house will use approximately 20% less energy to heat compared with a typical modern house meeting the same building regulation insulation requirements. Another important property often not appreciated is the humidity store of earth walls, they can easily absorb moisture from the atmosphere and release it again when the air dries out thus resulting in an overall higher background humidity than a typical new building. This is much more comfortable and healthier to live with not drying out airways resulting in less susceptibility to throat infections such as colds. There has been much research to endorse what I’m saying here, particularly by “CRATerre-EAG” at the school of architecture of Grenoble in France, and professor Germont Minke of Kassel university in Germany. Most of the new building projects in these countries have been done in either rammed earth (a form of building not native to the UK using a drier mix of earth and shuttering, resulting in a quicker drying time but much less sculptural characteristics), or in adobe (earth bricks). Minke has also experimented with “sausages” of an earth mix on the inside of a highly insulated wall simply to get the benefits of some thermal mass inside the insulation and mainly the humidity store. For me however, there is nothing more satisfying than the massive three-dimensionally sculptured forms of cob, as I hope you’ll agree when you look at some of the photos available on this site.