Cob building is the art of building homes using earth materials. Earth has been used for thousands of years as a building material, and is probably still the most common building material on Earth. The word ‘cob’ comes from an old English word that means ‘a rounded lump or mass.’ We get our word ‘gob’ from the same root word. Cob is basically a mixture of straw, sand and clay. These natural building materials are often available right on the building site, so transportation costs for materials are greatly reduced or eliminated altogether. Once the walls are built (by stacking the cob to build walls) they are covered with plaster to seal them. There are no forms, brick shapes or frames. Since cob is basically the same consistency as modeling clay, it lends itself to organic shapes that are more curved and natural. An artistically designed cob home fits in with its surroundings. These structures feel more at home and in harmony with natural landscapes. In addition to making beautiful homes, cob can also be used to build sculpture, garden walls and outdoor ovens.
Cob is literally ‘dirt cheap’ since it is made from materials readily found in nature. Many cob homes I’ve visited have been built for less than $5,000, and a few have been constructed for less than $500! Not only that, but it’s so easy a child could do it. Ever make mud pies when you were a child? Then you’ve already got most of the basic skills to build with cob!
Due to the fact that walls in a cob home are one or two feet thick, they offer excellent thermal properties. When built with passive solar design in mind, these homes often don’t require extensive heating or cooling in temperate climates. The earthen walls capture heat from the sunlight in the daytime and radiate it at night.
The tradeoff with a cob home is that it is a labor-intensive process. The savings come in part from getting the materials for free, straight out of the ground. Building it yourself means additional savings. You keep the money that would have gone to pay a contractor. If you’re not a hands-on, do-it-yourself type of person, cob is probably not for you; but if you don’t mind getting your hands (and feet) dirty, then cobbing can be a very relaxing and meditative experience. Most of the cob structures I’ve seen were built by groups of people in ‘cobbing bees,’ where friends and neighbors get together for a weekend or two to share the experience. Since no power tools are involved, people often spontaneously break into song or conversation while cobbing together. It’s a great opportunity to socialize while doing something positive for yourself and the environment! In fact, people who have experienced cob building firsthand often talk about it in terms usually reserved for those who have undergone a religious experience. Cobbing brings people together at an instinctual community level.

To see some examples of cob homes, check out the gallery below.