Do earth walls need to be protected from the effects of weathering and erosion?
A. The essential protection for earth walls is provided by the building’s roof and there is no absolute necessity to protect the walls. In the past, cob farm buildings in particular were often not rendered externally. However, other than in cases where, for example, buildings are of only one storey and have deeply over-hanging eaves together with a high masonry plinth (in excess of 600 mm), some form of protective wall covering is normally recommended. It is essential to use renders, plasters and paints that are vapour-permeable. Advice concerning appropriate finishes for earth walls can be found in DEBA leaflet “Appropriate Plasters, Renders etc” on this website.
