|cob construction||Northern Light|
The concept of "cob construction" is controversial. Widely differing opinions are held by thoughtful, well meaning people. As the physics, metaphysics and culture of housing is complex, many subtle design compromises are required.
A great site for a high quality introduction to most "natural" building methods is www.zianet.com, the Black Range people and Katherine Wanik. The primary source for cob information may be The Cob Cottage Company..
My knowledge of Cob Construction is limited. I attended a natural building symposium in Northern California a couple of years ago where one of the main projects was a hybrid greenhouse/garden storage building featuring a rock foundation, with some straw bale walls and some cob walls. It had an amazing cob oven and an organic roof formed with found dead fall trees of wonderful shapes. I observed that cob construction seemed to be a woman thing, with most of the enthusiastic participation coming primarily but not entirely from young women. The men were participating as much to be around the women as to build a cob structure...but I digress.
Cob structures are generally constructed with a heavy mixture of clay, sand, straw (and water) much like adobe or rammed earth, but unlike adobe, no (dry) bricks are made, and unlike rammed earth, no forms are used. The wet "adobe" is formed into walls of about 18 inches thick by hand in a rigorous process of transfering small "loaves" of cob to the top of the formed wall, and pounding into place by hand, shaping and forming as one goes up. Clearly this process lends itself to irregular, organic wall shapes. It is a wonderful but exhausting hands on process...something to fall in love with.
Structures to date tend to be small, hobit like, very sculptural, with windows formed directly into the cob with or without rough bucks, poured adobe floors, often with rock foundations. In the "natural building" spectrum, cob is probably the closest to "natural" being built today...in the first world.
Please, if you have a perspective, comment or information that will add to this feeble introduction please send them along and I will include them here under your byline. Thanks, Robert.