Cob is an ancient building material used around the world for centuries. It is composed of clay soil, sand and straw, and mixed together with water to produce a thick, load bearing building material which is built up in lifts on a prepared foundation. The lifts are between 1- 2 feet high and are left to dry somewhat before adding another course of cob on the wall. In this way, a cob wall grows until it reaches its full height. Walls are generally quite thick, usually 18-24 inches, tapering slightly as they go up.

Being a clay based material, cob lends itself to being sculpted in many ways. Shelves, benches, niches, arches and bas releif are all common elements in a cob creation, as are curvilinear walls. All of these elements combined make cob a truly unique building experience.

Cob can be mixed by hand, and by foot, either by yourself, with a friend, or in a workshop setting. This works great, but can be somewhat slow. It can also be mixed in a cement mixer, which is quite a bit faster. We mix our cob with a tractor, using a rotary tiller attachment. This works really well, is very consistent in its mixing ability and is quite fast, usually producing about 5 quality cubic yards of cob per hour.

Cob is a wonderful building material, being totally nontoxic, sculptable, strong and from the earth. I hope you enjoy these pictures and are inspired to build with cob, the worlds most sustainable and fun building material.