It is to cob that we owe the beauty of villages such as Broadhembury in Devon, where the eyebrows of thick thatch droop so heavily over the windows that the cottages look as if they have fallen asleep. And it is the very flexibility of cob, with its story-book dimples and curves, that makes the cottages of Devon, Wiltshire and Hampshire look almost edible.
Such is the interest in cob these days that a good example will often attract parties of architectural historians and craft enthusiasts, who come to touch the lumps and bumps, and appreciate the thermal qualities of this clever old building material. Ann Adams has such a house in mid Devon; she finds the attention enjoyable rather than intrusive.
'This area is rich in good red cob, but very few houses have been built with it since 1820 because people switched to stone,' she said. 'I found a tithe map dated 1842. Half the thatched farms on it were no longer shown on a map made in 1872.'
With the recent renewed interest in the use of natural products, renewable resources and craftsmanship has come a trickle of planning applications for the building of new cob walls for extensions or adaptations of existing buildings. Ann Adams's house was built in the mid- 17th century, though shards of medieval pottery in the garden wall suggest there was a dwelling here in the 12th century. The house was extensively overhauled in 1809 by a George Snell, who placed a large ornamental plaster plaque with a hanging shield over the front door to ensure that his work was never forgotten. Mrs Adams has made her own efforts, though she hasn't advertised her restorations so forcefully.
'I bought it because I thought it was historically interesting,' she said. 'I knew cob was a sound material as long as it was kept off the ground, standing on a good stone plinth, and as long as it was well roofed. My walls average 28 inches thick, a heck of a lot of mud. They are quite delightful to live with, because the house is never hot or cold.'
She was also intrigued by the layout of the house, which has a two- storey lobby entry in direct line with the chimney, capped with thatch. Enter the porch and you find your nose pressed against the chimney breast and have to go sharp right or left to avoid it. It also has three bread ovens. One is in the sitting room and was probably abandoned at the end of the 18th century, when fashion dictated that cooking should be removed to a utility room rather than done in the living room. Fashion then was not as flighty as it is now. 'It took at least 50 years for new ideas to travel from London as far as here,' said Mrs Adams.
When she replaced the rendering at the front of the house she found her cob in beautiful condition underneath, needing no repair at all. But to her great surprise she found a set of windows, dated 1680, buried inside the walls. She had already had oak- mullioned windows with simple leaded lights designed and made at great expense, so her delight at finding the hidden story in the walls was mingled with pangs of regret.
'I had no hesitation, though. I had the old ones fully repaired and restored and put the new ones in as well. They sit well together and bring a lot more liveliness to the facade.'
Nearby are two enormous barns with exposed, unplastered cob walls, both of which have been listed. Though exposed cob is relatively common in barns, architectural historians are unsure how often cob was left like this in houses; it is usually found cased in lime plaster.
Recently, however, the Devon Historic Buildings Trust found a cottage with an exposed cob wall at the rear, which has clearly never been plastered. This has excited speculation that many cottages may originally have been rendered only at the front in order to look smart.
It is hard to imagine how humble many of the dwellings must have been, but Richard Carew, a surveyor of buildings in the late 16th century, described seeing cottages built of rammed earth 'with low thatched roofs, few partitions, no planchings or glasse windows, and scarcely any chimnies other than a hole in the wall to let out the smoke.'
It is only relatively recently that experts have come to acknowledge that there are many more houses that resemble sophisticated mud pies than was thought before. Many cob houses were concealed behind curtains of stone, brick or flint, erected by the priggish Victorians who presumably considered it somewhat unclean. But a cob cottage usually reveals its inner soul to the passer-by through its slumped appearance, and its haphazardly placed, tiny windows.
The method of building is described by Adela Wright in her book Craft Techniques For Traditional Buildings. She interviewed one of the last clay-lump (Norfolk cob) builders of East Anglia. He described the business of digging up the clay in the autumn and leaving it out through the winter to let the frost break it up. It took more than a year to build a house in this way; then the lump walls had to be left to settle for two years, and to shrink, before the base was covered in tar to waterproof it.
'The old clay-makers would dig a pit, pond or pool about 36 inches down and the clay was thrown into this wet morass,' he said. 'They would also add short straw or quicks, a water grass. When farmers cleaned the land they would carry heaps of quicks to the builders. The clay would be kneaded by the feet of a tethered horse walking round and round, a great cruelty really - the poor beasts did not like the sticky clay hanging to their legs.'
It is as well that the Victorians did not know the full extent of what went into this most basic of building materials. 'We had one man who used cow dung in plaster for interior and exterior work and inside chimneys,' said the builder. 'It was important that the dung was fresh and had the morning dew still on it: it would make anything stick. Another builder would use urine in all types of plaster and in colour wash.'
There were many different methods for creating mud walls around the country. In some areas turf was cut into sods which were dried and then laid in layers to make peasant or animal dwellings. In East Anglia blocks of yellow clay and straw were cast in iron moulds, left to dry and made into walls with a type of clay mortar; this was known as clay lump. On the borders of Buckinghamshire and Oxfordshire a maverick kind of chalk cob known as wychert was used to make many of the old houses and walls in the village of Haddenham.
But the cob we are most familiar with is wet mud made from loamy earth which could be mixed with chopped straw, reed, chalk or gravel and sand, and laid in layers, each one being left to dry before the next one was added. Doors and windows had to be cut out when the walls were finished. The ribbon of black tar you sometimes see around the base of the walls was painted on to prevent the cattle licking away at them.
The real hazard with today's cob cottage, however, is not the slavering tongue of the cow but the invasive quality of the modern cement mortars that have been used in repairs. 'The introduction of cement acts as a water trap,' said Peter Child, conservation officer at Devon County Council. 'The water gets behind the cement and can't get out again. In the end the wall collapses.' Had flexible lime mortar been used which can absorb and lose moisture according to the seasons, these disasters might have been avoided. The word is spreading, however, about how these houses should be treated. There is a new Earth Movement in this country, which held its first international conference last month. It was organised by the Centre for Earthen Architecture at Plymouth School of Architecture, covering the span of earth building from the mud and stud method of Lincolnshire to the equivalents in Hungary and France.
'We realised that the whole country is scattered with these rural buildings that have been made from earth. The problem is that the skills have long since gone, so we are trying to revitalise them,' said the organiser, Linda Watson. 'The idea is that we need to encourage the use of earth as a contemporary building material, for aesthetic as well as environmental reasons. Cob isn't just a folksy tradition.' Attempts are being made to put a science to cob, by seeing how different urban soils perform in buildings, so that it can meet regulations laid down by local authorities.
Others have tried this before.
Pastoral architects such as Clough Williams-Ellis in the 1920s admired the simplicity and economy of cob building and designed cottages to be built from local earth. Probably the last major cob building to be constructed in Devon was a house at Budleigh Salterton, designed by the Arts and Crafts architect Ernest Gimson and finished in 1912. Then, after a break of 60 years, a cob
builder called Alfred Howard erected a new bus shelter in the village of Down St Mary, near Copplestone, in 1978. The revival had begun.
HOUSES FOR SALE
Cob houses tend not to be very grand. As Olive Cook writes in her book English Cottages And Farmhouses: 'All the delight, all the significance of these little houses lies in their diversity, in the informality of their haphazard compositions, so often exaggerated by a huddle of lean-tos, outshots and projections, in the unsophisticated craftsmanship which has given each one of them its own singularity, above all in the way they are absorbed into the landscape, settling into it as naturally as a yellowhammer's nest into a hedgebank.'
Devon remains particularly rich in cob. The county council estimates that at least 20,000 houses survive, though many have been so extensively restored that they may have lost some of their apparent spontaneity along the way. Yet they retain a strong grip on the imagination of the househunter. One of the most sought- after cob house types is the classic Devon longhouse, originally designed for animals to live at one end and humans at the other. Some were built of granite, but many are of cob, covered by heavy hoods of thatch to protect them from the rain.
Owls Castle is a former Devon longhouse in the wide Yarty Valley, near Axminster, constructed out of cob mixed with flint and stone. It was originally built in 1425 as a simple hall house, as the medieval soot retrieved from the inner layers of thatch proves, but now has an upper floor with four bedrooms. The owners have carefully redecorated, leaving the stone flags and beams exposed, and have rethatched it before putting it on the market with Jackson Stops & Staff for pounds 250,000, including outbuildings and paddocks.
Cottages on a much smaller scale can often be found in Hampshire, particularly in the New Forest. Fernhill Cottage, near Ringwood, has wonderful curiosity value since it is built partly of cob and partly of brick, under a new thatch. It is set in woodlands with a stream, pond, weeping willow and wishing well in the gardens. This little slice of Hansel and Gretel is now being sold by Savills at pounds 185,000.
Another charming two-bedroom Hampshire cob forest cottage, near Sway, is for sale through John D Wood at pounds 175,000 including a pony paddock.