In addition to its structural role, the foundation usually separates the man-made indoor climate from the actual environment of the ground. The implications of this secondary role are sometimes not fully appreciated by the designer, with serious consequences. The structural success of shallow foundations on volume-changing clays may be governed by their net effects on the subsoil environment. The significance of changes from natural ground conditions by construction must be appreciated at least qualitatively by the foundation designer. Natural and artificial changes in the thermal, the moisture, and the stress environments of subsoils are discussed in this paper, with particular emphasis on the clay soils and the climatic conditions of Western Canada.