There are many varieties of walling construction throughout Britain which use earth in an unbaked state.  These range from the unshuttered in-situ mass loadbearing walls based on clay and/or chalk and aggregates found in many areas, through the clay lump found predominantly in East Anglia, to the'mud and stud' found predominantly in areas in and around Lincolnshire.  In some areas, and perhaps particularly in some eastern areas of Scotland, types akin to all those described above can be found.  Also, fairly commonly, earth walling has been used compositely with other walling materials.  Less commonly, but still significantly, earth (or perhaps more often, chalk) which was rammed into place between shuttering can be found.  Also, earth has been used in wattle and daub construction.  However, this leaflet concentrates on those types which contribute significantly to the load-bearing capacity of the wall.  A range of these is shown at Figure 2.

Of these, the in-situ mass loadbearing unbaked earth wall is almost certainly the most common surviving type in Britain.  The greatest numbers of buildings with such walling can be found in Devon and other counties of South and South-West England, where the material is commonly termed 'cob'.  The following content dealing with typical problems and types of repair relates largely to cob and similar walling.  To an extent it applies to other earth walling types, but those advising on, specifying or implementing repair techniques should seek to fully understand the composition and construction technique associated with the particular wall in question, since what is

appropriate in one situation may not be in another.  Even within a very limited locality, indeed sometimes within an individual building or group of buildings, the composition and technique can vary considerably.

In the south west and many other regions, the use of cob type walling traditionally is associated with thatched roofing, although there are exceptions.  Figure 1 shows typical features of a vernacular dwelling in South West England, albeit that the plan form shown may not be the most common throughout the region.  It seems that rarely are the qualities of cob walling discussed without reference to the old adage that'all it needs is a good hat and a good pair of boots and it will last forever'.  This expression does serve to remind us that in assessing the condition of an earth walled building, the cause of any problems may lie outside the earth walling itself It also suggests that the commonly held view that earth walling is inevitably a poor form of construction is somewhat ill-founded.  Indeed, the fact that examples dating from the late 15th century survive and continue in use is testimony to its durability when weil constructed and appropriately maintained.  Of course, as with other construction types, poor quality examples can be found which display inherent constructional problems.  However, there is little doubt that many of the problems associated with such walling arise through neglect, inappropriate modifications, or inappropriate maintenance and repair techniques.  This leaflet seeks to focus on some of the problems commonly encountered, and consider appropriate ways of dealing with them.