Cob is an ancient technique of building monolithic walls using moist earth mixed with straw. It can be used to create almost any shape, and has wonderful sculptural qualities. Cob is easy to work with and requires few tools. Cured cob possesses excellent strength, and is a good source of thermal mass.
To build with cob, we mix local soil with aggregate and straw to create a stiff mud, which is formed into small loaves (cobs). These cobs can be tossed to a builder on the wall who mashes them together on top of a stone or concrete foundation.
The relatively thick walls (usually 12″-24″) are built in courses from 6″ to 16″ high. We let the layer dry and solidify before adding more height. Irregularities in the wall can be shaved off with a spade or other sharp tool as work progresses.
Vital Systems uses cob together with other natural building systems to create walls and unique sculptural work for benches, fireplaces and other highly visible aspects of construction. We have pioneered the use of mixing machinery which makes cob, as well as earth plasters much more viable for large projects.