The First Cob Building Code in North America

For the first time, cob construction has been included as an appendix to the 2021 International Residential Code (IRC). The IRC is part of the International Code Council’s (ICC) model building codes, which form the basis for most building codes in the United States. Cob Research Institute (CRI), a nonprofit organization started in 2008 with the mission “to make cob legally accessible to all who wish to build with it,” developed the appendix as a public service — the result of years of research, collaboration, and testing at several universities and laboratories. The appendix and its supporting documents can be found on the CRI website, www.CobCode.org.

Also known as “monolithic adobe,” cob is a method of earthen construction that has been used for thousands of years around the world, including in Britain, Northern Europe, the Middle East, West Africa, China, and the Southwestern United States. A stiff mixture of clay soil, straw, water, and usually sand is placed in integrated layers to create monolithic walls that can support a roof with no need for structural posts. Properly designed, constructed, and maintained cob