Cob building techniques provide a number of advantages including lower materials cost, passive solar heating for reduced utility costs, acoustic privacy and greater resistance to fire than conventional building methods. Cob construction techniques utilize a mixture of clay, sand and straw. The clay acts as an adhesive, while the straw provides tensile strength once hardened. Cob is a very flexible material and is easy to work with.
One reason cob construction methods are attractive is because they utilize materials that may be either sourced on site or purchased for relatively little cost. Clay is abundant in most areas of the world, and building structures using cob techniques can offer considerable savings. Cob techniques typically require fewer workers and workers that have less skill or experience may still be able to employ these techniques effectively.
Unlike conventional homes, which make use of synthetic materials and industrial components, cob techniques utilize only natural materials. Conventional homes and structures may contain air pollutants created by the off-gassing of chemicals used in their construction materials while cob construction creates surfaces that have tiny pores that facilitate the exchange of air. For this reason, cob building techniques are ideal for people who suffer from allergies or respiratory medical conditions.