A flood resistant building foundation

This invention relates to a flood resistant building foundation in which a sub base 14 is used to resist the flood water pressure by coupling together the combined weights of the building, the foundation, sub base 14 and infill material (28 figure 3). The sub base 14 may also provide increased strength by having increased depth. The sub base 14 may be secured to the foundation beams 7 which have a cast in slot and threaded insert. The sub base 14 may be cast in place and connected to the foundation beams 7. In other cases such as plinths for bungalows or lightweight buildings, the sub base (29 figure 4) may be in the form of pre cast sections (31 figure 4) which may include cast in or added stiffening ribs (32 figure 4) for increased strength which may also form pockets (33 figure 4) for the retention of infill material (35 figure 4).