A proposed diagnostic survey procedure for cob walls

Following the publication of the systematic analysis of some 20 failed cob buildings, this paper proposes a diagnostic survey procedure for cob walls. The earth building research team at the University of Plymouth has been studying the causes of structural failure both by laboratory studies and observed material based upon real building failures. A definition of a healthy cob building is presented, and this is followed by an outlined check-list whereby unsound cob walls may be identified. This survey check-list has six steps: (1) a site analysis, (2) building description, (3) maintenance and repair history, (4) building condition, (5) a moisture content analysis, and (6) a cob material composition analysis. There is a need to refine and develop the proposed survey procedure in order to establish a working tool that building surveyors can use in the field, which would include a troubleshooting guide, and the discussion addresses the main issues.