Building in Cob, Pise and Stabilised Earth

Citation

Staveley, H.S. (2001), "Building in Cob, Pise and Stabilised Earth", Structural Survey, Vol. 19 No. 1. https://doi.org/10.1108/ss.2001.11019aae.002

Building in Cob, Pise and Stabilised Earth

Building in Cob, Pise and Stabilised Earth

Sir Clough Williams-Ellis, John Eastwick-Field and Elizabeth Eastwick-FieldDonhead Publishing Ltd1999ISBN: 1 873394 39X164 pp.£30.00

This fascinating volume, first published in 1916, had by 1947 run into its third edition and in the interim had been increased from 125 to 164 pages. There were new chapters on adobe, stabilised earth, design, foreign practices and protective coverings. This current edition is a facsimile of the 1947 third edition. It is of particular interest to conservationists, architects, surveyors and, dare I say, structural engineers engaged in structural surveys of older properties particularly in a rural context. As an example of the potential use to a surveyor, many years ago I was baffled by a single-storey house in the older part of Sidmouth, Devon where the external walls were a mere overall thickness of around 180mm. On removal of some plaster, they were found to be built out of 450 x 230 x 150mm rammed earth pise blocks formed from earth dug out on site, bedded in lime mortar and plastered both sides. The use of unburnt earth in this context is described and specified fully in Chapter 2 of the book.

Sir Clough William-Ellis' intention in this 1947 enlarged edition was to speed and cheapen the building process in the aftermath of two World Wars by using, as far as possible, materials available on site. Unfortunately, this has not proved popular for new building due to the high labour costs involved as compared with the cheapness and ready availability of concrete blocks, bricks and other modern materials. There may also be some difficulties in compliance with the current Building Regulations. This form of construction is therefore of greatest use in a historical context for those concerned with the survey, repair, modification and administration of such existing buildings. Of course, in other countries where labour is cheaper and other materials less available than here, pise and cob would make far more economic sense and this volume would be of great use to those practising in, for example, Third World countries.

In the first chapter of the book, the author classifies the different forms of construction (pise, stabilised earth, cob, chalk and earth blocks) then goes on to discuss their relative values, standards, performance in use and comparative costs. The latter, in the light of the current economy, is open to question.

Chapter 2 has already been mentioned, but in this he also stresses the perceived advantages of pise construction, building techniques and gives a sample specification. Both shuttered, rammed pise a terre and pise blocks are described together with the best and worse types of earth to use for these purposes together with samples of construction.

The next chapter on "Adobe", would seem more applicable to those drier countries overseas, as buildings constructed in this manner use clayey, sun-dried unburnt bricks, usually with a moulded size of 400 x 200 x 150mm. Again, detailed instructions as to content and use are given both for employment at home and overseas.

The following chapter on "Stabilised earth" describes the use of soil/cement mix for shuttered in-situ walls and blocks, also introducing bitumen-stabilised earth. Once again, methods of mixing, curing and using are given and the minor alternatives of resin and oil binding discussed.

Chapter 5, on "Cob and chalk mud", is of particular contemporary use due to the resurgence in cob construction, particularly in the West Country. For instance, he mentions the Centre for Earthen Architecture at the University of Plymouth and bodies such as English Heritage, the National Trust and the Conservation group of the RICS are showing increasing interest in the subject. Here, in East Devon, there is a large population of older agricultural and domestic low-rise buildings in cob and thatch where, provided details such as adequate eaves overhangs, watertight external finishes and 1m high stone plinths are followed, proves to be an excellent form of design for most rural buildings. It is not only fashionably environmentally-friendly but also weathertight (if properly maintained) and has first-class insulation qualities. The author goes on to mention Hayes Barton, home of Sir Walter Raleigh in East Budleigh, which to my personal knowledge is a cob and thatch property still in excellent condition; also Mr Gimson's house in Budleigh Salteron, another cob and thatch building which, although approaching 90 years old is still in sound watertight condition. Recipes for cob and chalk mixing are described with the tools to be used and the methods of construction.

The remaining four chapters describe protective coatings for earth walls, design and overseas practices and there is also a chapter on a successful experiment carried out by the Ministry of Agriculture and Fisheries together with the Department of Scientific and Industrial Research. The latter involved building cottages in the village of Amesbury, Wiltshire, using differing forms of earth construction for comparison with those built using orthodox materials.

In conclusion, the book is profusely illustrated by 60 clear printed plates (not in colour) together with 46 well-conceived and instructive drawings and diagrams. Sir Clough Williams-Ellis has written a book which, even today, fills a gap for those interested in conservation, the environment and historical building methods. Although the text may, in parts, appear somewhat stilted by modern standards, this only adds to its charm in spite of the comparative costings being somewhat out of date. The book makes compulsive reading and emphasises that Sir Clough William-Ellis' talents were not confined to the trompe-l'oeil which is Portmerion!

H.S. Staveley