Cob is an ancient building technique which uses clay rich soil, straw, sand and water. These ingredients are mixed together by hand, using tarps, or by machinery. The mix is formed into lumps or "cobs" which are pressed together to form the walls of a building. Cob affords an artistic, curvilinear, sustainable construction process.

When left to dry the cob sets to become extremely hard, durable and structural, although in wet areas like Britain cob walls need protection from driving rain which will eventually erode them. A large overhanging eve and a lime based plaster are usually used. There are thousands of 100 plus year old cob houses still inhabited in England today.

A simple technique to learn, safe, non toxic and lots of fun to build with, you can use cob to create almost any structure - from the simple to the fantastic. Cob structures can be finished using different mixes of the same materials, to produce beautiful paints, plasters, floors and sculptural features.

Cob building uses the world's most abundant and sustainable building materials, has very low embodied energy, and its cost is minimal. Virtually all the materials used in the cob building process are biodegradable or can be recycled, making it one of the most environmentally friendly ways of building.

Why build with earth?
Save - A third of the world's land mass is suitable for building with earth which means the majority of the building material can be found on or near the site. This reduces the cost of transporting and processing the bulk of materials used in construction. It also saves exploiting new resources by incorporating recycled materials into the design. Cob is load bearing and needs no framework. A house made of earth typically uses 60% less lumber than a stud frame building.
Increase - By careful consideration of the site, passive solar design and the integration of indoor and outdoor spaces, cob building increases the awareness of natural systems, our impact on them and how we can build in balance with these systems.
Reduce - Cob building reduces the need for specialist skilled labor and expensive equipment. The construction techniques we use are easy to learn and reduces the amount of money required to build structures. Typically in America a house might cost $200,000. but with these techniques people have built their own homes for less than $2000. The flexibility and fluidity of cob building allows for curvilinear shapes which enclose space most efficiently reducing the size of building required.
Improve - Cob building improves the quality of the environment, the materials used for building as well as finishes such as paints and plasters are non-toxic and non-polluting.

The importance of sustainable building
Modern building methods are environmentally destructive and their impact on our environment is huge. The extraction, processing and transport of materials, the energy involved in their construction, maintaining the environments within them and the problems of recycling/disposal when they are destroyed creates a massive drain on our resources, pollutes our air and water and is ultimately unsustainable.
Buildings can isolate and dislocate us from the natural systems with which we are interdependent or they can empower and educate us to achieve an harmonious balanced relationship within these systems. Therefore if we as a culture wish to address with any credibility issues of waste reduction, consumption and sustainability we must develop a built environment which reflects and promotes these aims.

Sustainable building technologies, a glossary of terms
Cob - a traditional mixture of earth, sand, straw and water mixed by hand or machinery. Formed into lumps and pressed together to form the walls of a building, rather like building a giant clay pot. Cob structures are load bearing. Excellent thermal mass which is necessary for passive solar design.
Adobe - a mixture of earth, sand straw and water mixed by hand or machinery, formed into bricks which are then left to dry out in the sun. These are used in a similar way as conventional fired bricks to build walls. Adobe is load bearing.
Wattle and Daub - A woven willow or hazel framework (Wattle) is then daubed with a Daub plaster mixture of earth and dung and sometimes horse hair. Used as infill in a timber framed building.
Straw bale - Can be used as an infill to timber frame structures, straw bales are used as an very effective insulator. They can be load bearing if they are pretensioned. Bale walls are then sealed with a earthen or lime plaster.
Timber - Uses large diameter/section timber posts and beams to form a framework of a frame building. The gaps between the timbers require another building material to infill the walls.
Light straw - Shuttering is created to ram straw dipped in a clay slip as an infill to a timber clay frame structure. Very good insulator.
Earthships - Using discarded tires, earth is rammed into them, they are then bermed into a bank and daubed with a cement or lime plaster.
Rammed earth - wooden shuttering is created then a mixture of earth, sand and water sometimes stabilized with cement. The mixture is rammed between the shuttering often using hydraulic machinery. The forms are removed to leave load-bearing walls, sealed with an earthen or lime plaster.

Currently most of the photos on this site are inspirational & credited via linking to thier owners site. If you own any of these photos & don't wish them used please e-mail me karl(at)omelay(dot)com & i'll promptly remove them.

As our construction progresses we'll be able to use our own photos to highlight techniques & inspirational ideas. We intend no profit and only wish to spread the word about cob and strawbale construction.