Foundations are the lowest load-bearing part of a building, usually below ground level, through which the loads of a structure are distributed on to the ground. The quality of the ground and the kind of structure determine the type of foundation used. Spread foundations are broad and shallow and, where firm ground exists near the surface, are the simplest to build. Otherwise, where solid material lies beneath unsuitable ground, the loads are transferred through the poor surface material to considerable depths using piling or a caisson. In the past, foundations for brickwork consisted of large stones, timber beams, or simply a thicker base, or footing. Wide walls were built on the ground without special foundations. Nowadays, for load-bearing walls, the spread foundation is a continuous concrete strip that is wider than the wall. For a column or pier, the spread foundation is a rectangular pad of concrete.
In the 19th and early 20th centuries, before the adoption of reinforced concrete, steel columns were often supported on layers of steel joists (a technique known as grillage). Where poor ground requires the foundation to be of about the same area as the building, a raft is used. A small raft may be a reinforced concrete slab; a larger raft may be a slab stiffened with beams. For buildings with basements, the lower storeys may be built as a stiff box. Research Foundations
Abbreviations
Architecture
Research Foundations