Bob Nother gives practical advice on caring for and repairing cob, clay lump and similar earth buildings LOOKINGAFTER EARTHBUILDINGS The subject of earth buildings has received some coverage in Context during recent years. Dirk Bouwens outlined the spread of surviving earth buildings throughout Britain, and provided very useful case study material on the repair of clay-lump buildings in East Anglia. ( Context 41, March 1994, ppl9-21) Prior to that, John Preston had given an account of a practical session dealing with earth building construction and repair. (Context 32, December 1991, p20). The definition of an earth building is open to different interpretations. In this article, the principal walling material being considered is a conglomerate based on suitable subsoils found in the immediate locality of the building, and mixed and laid in an unbaked state. In the majority of situations, the walling forms a main loadbearing element, although there are significant exceptions to this. Documentary and archaeological evidence suggests that the spread of earth buildings formerly extended beyond the areas where significant numbers are known to survive today. Hence, it is possible that there are remnants of earth walling yet to be discovered in buildings outside these areas. Commonly, earth walls are concealed by different materials. They may have a facing of stone or brickwork, this being either subsequent modification or contemporaneous with the earth wall construction. This makes identification very difficult. Nevertheless, as the following content will show, it is known that very many earth buildings survive. These form an important part of our built heritage, and it is alarming that many seem to be lost or seriously threatened through ignorance of how to look after them. During his research for a MSc dissertation in 1994, the author gathered information about the spread of earth buildings throughout mainland Britain. He is very grateful to those conservation officers (more than 70% of those approached) who responded to his questionnaire, and apologises for not having been able to thank each respondent individually. The questionnaire included amongst other things a request for information on very approximate numbers of structures and prevalent types of earth wall construction. 22 Perhaps this was expecting too much of already overworked conservation officers! Nevertheless, a good proportion of the respondents were able to provide the requested data, and when coupled with other documentary sources, a useful country-wide picture emerged. In England, there are many areas (e.g. Cumbria; Llncolnshire/Nottinghamshire; the East Midlands; Oxfordshire/Buckinghamshire) where in each the number of surviving examples probably runs to several hundreds. In East Anglia the numbers are thought to run to thousands. However, there is little doubt that the greatest numbers survive in the south and south-west area ranging from Hampshire to Cornwall, in all probability totalling well over 50,000. The vast majority of these are in Devon, possibly amounting to more than 40,000, of which about 50% are dwellings. In Dorset, the county in which the author has carried out the major part of his research, there are probably several thousands of buildings containing earth walling. Cob walling is described in about 400 of the Dorset listing entries, but there areverymanymorelisted buildings which actually contain the material. Of the many unlisted examples, a large proportion are remote and outside conservation areas, and the prospect of saving those under threat from demolition or neglect through redundancy issometimes severely limited. Undoubtedly, this is a situation all too familiar to conservation officers in other areas containing earth buildings. Reluctantly, perhaps, some losses have to be accepted where such buildings can no longer provide beneficial use and where no statutory protection or financial aid scheme exists. However, of major concern here is the threat to earth buildings arising from a lack of understanding of how to maintain and repair them appropriately. Also, there still appears to be a common perception that earth walls are second rate construction not worthy of retention. This is in spite of clear evidence that in some areas a very significant number of the survivals date from the 17th and 18th centuries, and some are even earlier. In Dorset, as in Devon and other adjoining counties, the vast majority of earth walls are of monolithic in-situ construction, commonly termed cob. As with other building materials, the initial construction quality can vary widely, depending on the type and mix proportions of the constituent materials, and the quality of workmanship in mixing and placing. In the broader south-west region, other types of earth walling can be found; parts ofHampshire, for instance, having significant numbers of 'pise' buildings, where a mix much drier than that for cob under construction isrammed into position between faces of robust shuttering. With the exception of Lincolnshire, with its 'mud and stud' walling, and East Anglia, with its claylump walling, the predominant earth walling type throughout much ofEngland is akin to cob, albeit known by a variety of regional names. Commonly, the mix consists of clay, sand and larger aggregate, togetherwith some straw or other organic material. In some areas, particularly Hampshire, Wiltshire and parts ofDorset, chalk forms the major ingredient. It is important to recognise that earth walling mixes can vary considerably, even within a local area. For instance, in a few of the villages where the chalk belt and the alluvial deposits of Dorset's Piddle Valley meet, some buildings have walls of claybased cob and others have chalk. In this area there are individual buildings where both types of walling material can be found. In preparing proposals for repairs, it is essential to have an analysis of the walling material in question and a clear understanding of the causes of failure. Various published texts and leaflets include information on the usual constituent ingredients of earth walls, and deal with the analysis and remedying of defects. Some of these are listed below. Essentially it is down to owners to appoint professionals who will offer solutions based on a thorough understanding of the material and the way it behaves under certain conditions. Many conservation officers may find it difficult to persuade owners to take this route, particularly where the required work does not involve the need for listed building consent and a local jobbing builder is standing ready with his bucket of rich cement mix. Nevertheless, it is a message that needs to be pushed home at every opportunity, CONTEXT49
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