“What is Cob?”
Cob is a traditional building technique using clay, sand, straw and water- wet enough to shape, yet dry enough to build up without forms. The clay acts as the glue, while the sand gives strength to the mixture and the straw gives the walls tensile strength once hardened into place. It dries to a hardness similar to lean concrete and is used like adobe to create self supporting, load bearing walls. A cob house is essentially monolithic. This with it’s curved walls gives them greater strength in earthquakes. Earth is an abundant resource that can produce beautiful and sustainable homes with a minimal footprint.
Most of the materials used for building an earth house are unprocessed, natural and local products such as sand, clay, straw and recycled materials.
Cob invites creativity to be expressed in the process of building your space. Because cob is very flexible to work with, you are able to create just about any shape, curves, arches, shelves, benches, niches, fireplaces and ovens.
Earth homes are cool in summer, warm in winter. Cob’s resistance to rain and cold makes it ideally suited to cold, rainy climates like the Pacific Northwest, and to desert conditions.
History of Cob
COB is not a new material it is a building material that has been around for centuries. The word cob comes from an Old English root meaning a rounded mass or lump. It was started in England around the 13th century from other types of earth building techniques like adobe, sod, rammed earth, straw-clay, and wattle-and-daub just to name a few. Thousands of cob houses have weathered rainy England for hundreds of years.. Earth is probably still the world’s most common building material. With recent rises in the price of lumber and increasing interest in natural and environmentally safe building practices, cob is enjoying a renaissance. In this age of environmental degradation, dwindling natural resources, and chemical toxins hidden in our homes, doesn’t it make sense to return to nature’s most abundant, cheap and healthy building material?
What are the advantages of building with cob?
- Cob is gentle on the planet. Earth is non-toxic and completely recyclable, creates no waste, and requires minimal tools to construct.
- “Buildability” – Cob homes are owner built. It is easy to learn, cob is a very flexible and forgiving medium.There is obviously, quite a bit of labor involved but if time is not a factor, a house of this type could be built with just a couple of workers. Basic carpentry, plumbing and electric skills are required.
- It is Affordable and Inexpensive – The walls of the home are made entirely of natural resources that are available under your feet.
- Cob is very durable and requires little upkeep
- Energy Efficiency – A cob house provides a large amount of thermal mass. This helps keep the house cool in the summer and warm in the winter. It is ideal for passive solar homes.
- Fun – If you like playing in the mud, this is the house for you. Seriously, this is an excellent style of house to build for those with imagination. You can be very creative with the walls of your house. Also a Safe building material with kids.