stepped foundations---usuallyconsidered in the context of strip foundations and are used mainly on sloping sites to reduce the amount of excavation and materials required to produce an adequate foundation.

concrete foundations--concrete is a material which is strong in compression but weak in tension.if its tensile strength is exceeded ,cracks will occur resulting in a weak and  unnsuitable foundation.one method of providing tensile resistance is to include in the concrete foundation bars of steel as a form of reinforcement to resist all the tensile forces induced into  the foundation. steel is a material which is readily available and has high tensile strength.

short bored piles--a form of foundation which are suitable for domestic loadings and clay subsoils where ground movements can occur below the 1000 depth associated with traditional strip and trench fill foundations. they  can be used where trees are planted close to a new building since the trees may eventually cause damaging ground movements due to extractiong water from the subsoil and root growth. conversely where trees have been removed this may lead to ground swelling

simple Raft foundations--can be used for lightly loaded buildings on poor soils or where the top 450 to 600mm of soil is overlaying a poor quality substrata

Strip foundations--these are suitable for most subsoils and light structural loadings such as those encountered in low to medium rise domestic dwellings where mass concrete can be used. Reinforced concrete is usually required for all other situations.

Pad foundations--suitable for most subsoils except loose sands,loose gravels and filled areas. are usually constructed of reinforced concrete and where possible are square in plan

Raft foundations--spread the load of the superstructure over a large base to reduce the load per unit area being imposed on the ground and this is particularly useful where low bearing capacity soils are encountered and where individual column loads are heavy

Cantilever foundations---these can be used where it is necessory to avoid imposing any pressure on an adjacent foundation or underground service

Piled foundations--can be defined as a series of columns constructed or inserted into the ground to transmit the load of a structure to a lower level of subsoil. piled foundations can be used when suitable foundation conditions are not present at or near ground level making the use of deep traditional foundations uneconomic.the lack of suitable foundation conditions may be caused by: Natural low bearing capacity of subsoil  High water table:giving rise to high permanent dewatering costs; Presence of layers of highly compressible subsoils such as peat and recently placed filling materials which have not sufficiently consolidated; Subsoils which may be subject to moisture movement or plastic failure

Classification of piles--piles may be classified by their basic design function or by their method of construction:

end bearing piles,pile transmits load direct to firm strata-it also receives lateral restraint from subsoil

 friction or floating piles,deep layer of weak subsoil such as clay or silt-pile transmits load to surrounding soil via friction between surface of pile and soil which in effect lowers bulb of pressure

replacement piles, hole for pile shaft bored in the ground and the resultant void filled with reinforced or plain insitu concrete

displacement pile--preform pile driven into ground displacing the subsoil through which it passes