Cob Building: Hand-Sculpted Architectural Forms – Without the Use of Power Tools
Architectural walls, artistic benches, rustic earthen fireplace mantelpieces and much more can all be fashioned out of no more than the appropriate recipes of straw, sand and clay-rich earth. Cob building means sculpting by hand & mostly without the use of any high tech power tools. That’s why this material has formed the basis for human dwellings since the dawn of civilization.
There’s something about the smooth, hand-sculpted forms and the natural, earthy appearance that gives cob structures a presence unlike anything else in the built environment. Cob (earthen) structures have a unique, warm, almost friendly quality about them that cannot be replicated by modern building materials.
What is Cob, and why is it Green?
At it’s essence, cob is clay-rich earth mixed with sand, straw and a bit of water. Because it was traditionally mixed by being trodden by livestock animals, manure was a common component in days of yore, but is by no means necessary for a high-quality cob mix. Today, people often mix cob on big tarps and/or by stomping it with many human feet. For large projects such as homes or outbuildings, cob is often mixed with a rotor-tiller.
The primary component of cob – clay-rich earth – is dug directly from the subsoil. It is ecological in that it doesn’t consume any topsoil and has a very low-embodied energy compared to competing building materials. The straw component is a bi-product of the grain harvest that farmers have little use for aside, from fodder bedding for farm animals. Because it is created as part of the production of wheat, rice, barley and all other grains, straw is widely available and usually at a very low cost (farmers are generally happy to be rid of it)! Sand is usually available from a nearby quarry, so it too is relatively low impact. Water is normally available on-site.
You can see that with such simple, low-processed, locally available materials, cob building is beneficial for both humans and the environment! And the greatest thing is, it can be sculpted into just about any shape or form that you can imaging!