What requirements exist with regard to building foundations?

These are covered by Approved Document A and Approved Document C1 and are as follows:

The combined dead, imposed and wind loads are sustained and transmitted by it to the ground, safely and without causing any building deflection / deformation or ground movement that will affect the stability of any part of the building...ground movement caused by swelling, shrinkage or freezing of the subsoil, land-slip or subsidence will not affect the stability of any part of the building.

(Approved Document A)

(1) The ground to be covered by the building shall be reasonably free from any material that might damage the building or affect its stability, including vegetable matter, topsoil and pre-existing foundations;

(2) Reasonable precautions shall be taken to avoid danger to health and safety caused by contaminants on or in the ground covered, or to be covered, by the building and any land associated with the building;

(3) Adequate subsoil drainage shall be provided if it is needed to avoid:

      (a) the passage of ground moisture to the interior of the building;

      (b) damage to the building, including damage through the transport of water-borne contaminants to the foundations of 

           the building.

(Approved Document C1)