The eluvial soils often found at sites of construction consist of the products of weathering, and their strength and deformation properties vary widely (from fissured rocks to loose sands and fine clayed soils). This examination of the physical and mechanical properties of eluvial soils describes modern methods of evaluating the degree of weathering, deformation and strength characteristics, as well as frost heave, in such soils. Problems of the design of foundations on eluvial soils of various degrees of weathering, from jointed rock to loose sand and silt clay formations, are also highlighted.