Rafts may be divided into three types, based on their design and construction:
(i) Solid slab system
(i) Beam slab system
(iii) Celular system
All the three types are basically the same, consisting of a large, generally unbroken area of slab covering the whole or the large part of the structure. The thickness of the slab and the size of beams (if any) will be governed by the spacing and loading of the column and degree of rigidity required in the raft.