Raft foundations (sometimes known as MatFoundations) are a large concrete slab which can support a number of columns and walls. The slab is spread out under the entire building or at least a large part of it which lowers the contact pressure compared to the traditionally used strip or trench footings.
Raft foundation is a thick concrete slab reinforced with steel which covers the entire contact area of the structure like a thick floor. Sometimes area covered by raft may be greater than the contact area depending on theof the soil underneath. The reinforcing bars runs normal to each other in both top and bottom layers of steel reinforcement.