This Digest and Digest 64 show how soil conditions on site affect the design of foundations and the subsequent behaviour of buildings.

In the past the choice of foundation type has been little influenced by soil conditions but the increasing use of sites with difficult soils has more serious implications for foundation design and calls for a better appreciation of the way soil reacts to applied loads and natural forces.

This Digest therefore considers the principles of soil behaviour and examines the movements which result from the construction of foundations or which can be induced by other factors such as weather, vegetation and subsidence.

This Digest was first published in 1965 with revisions in 1976 and 1985.

Digest 64 deals with the choice of building sites and the investigations necessary to determine soil conditions. Digest 67 considers the types of foundation most appropriate to these conditions.

Digests 240 and 241 provide supplementary information with a focus on clay soils.