Cob is an old word which has quite a few meanings. In this instance it is a mixture of clay soil, straw and water, which can be used to build structures that have the potential to last for centuries.
I have been working with earth in many ways for a long time, but in the last few years I have concentrated more on building with cob as it is such a beautiful material to use and to live in. Where I live, in South West Portugal, the soil is perfect and all the old houses are built with rammed earth. What’s the difference? Well, rammed earth requires a wooden form, which does restrict the shape of the building and is really hard work! Cob is more flexible. The buildings can be curved and crazy.