Protection is less here than higher up under the projecting eaves, and the Achilles’ heel of the cob wall is undoubtedly its base.
This vulnerable part, exposed as it is to driven rain, back-splash, and the casual kicks, should be given special protection.
Where the base is of cob and not of masonry, the traditional method is to provide a good deep skirting of pitch or tar, or a mixture of both, applied hot to the face of the rendering that should completely cover the exterior of all cob work.
This rendering is usually composed of lime and hair mortar, though Portland cement has come into use to some extent recently.
Cement, however, is apt to be rather too “short” and brittle, and it does not always hold to the cob walling very securely.
A rendering consisting of an equal mixture of cement and lime with three parts of sand adheres well to cob, however, and is probably the best coating that can be given to it.
This coating can be colour-washed or lime-whited in the usual way. The granular surface of rough rendering or of “slap-dash” on the slightly wavy surface of cob walling perhaps gives to whitewash its very highest opportunity and charm.
Certain it is that the old cob cottages of Devon with the pearly gleam of their white walls, their heaving bulk of thatch and their trim black skirtings, are as gracious and as pleasant to the eye as any in all the length and breadth of England.
Within, lime-and-hair mortar plastered straight on to the cob makes an excellent lining.
Chimneys.—Nowadays, chimneys are commonly built up in brick or stone, but numerous good examples survive of flues and stacks constructed in cob. The insides of these are pargeted with lime and cow-dung in the usual way, brickwork being only introduced immediately around the fireplaces.