Mat or raft foundations are type of the shallow foundations, which covers the entire area beneath a structure and provides support to all the columns and walls. It is also a type of the combined footing where all the footings are combined in the following cases:
- When the columns are so close such that their footings nearly touch each other.
- When the soil is weak and having the low bearing capacity.
- Where chances of differential settlement exist due to either the existence of the different soils or variation of the moisture content.
- or where there is a large variation in the loading in the adjacent columns.