No artificial methods of drying are at present usual, beyond good fires inside during the winter, though, as under such conditions a cob cottage is not usually considered fit to live in for several months after completion, some artificial means of drying might be worth considering.
Foundations and Base.—The depth of the excavations required for the foundations naturally depends upon the character of the site and soil, as also does the spread of the footings, if any.
The base-course wall of brick, stone, or concrete should be carried up some 2 ft. or so above ground level. In old days this walling was not infrequently built “dry”—but good lias lime or cement should be used in all new work.
The damp-course too was an unknown refinement to the by-gone builders, and the introduction of this one improvement alone makes the new cob cottage a very different dwelling from the old.
The usual forms of damp-course serve well for cob walls, though slates laid butt and broken joint in cement are probably the best.
Walls and Roofs
Thickness of Walls.—The thickness of walls may be anything you please from 18 in. upwards. There are old examples a full 3 ft. across, but for an ordinary two-storied cottage a thickness of about 2 ft. is general. Eighteen inches is certainly the minimum thickness, and would not ordinarily be adopted for any but one-storied buildings.
The first-floor walls are made the same thickness as those below, for if they were reduced in width, as is usual in a stone building, the extra weight thus thrown on to one side of the ground floor walls would tend to make them bulge, unless quite dry and thoroughly set.
There are old cob walls in existence fully 30 ft. in height, and there is no apparent limit in this direction provided they are thick enough.
The upper layers compress the lower ones, and automatically render them more dense and stone-like and fit to bear the load imposed above.