Foundation(Footing) is the lowest part of the structure below ground level which provides a base for the building. It is the part of structure which receives the load of the building and transfers it safely to the lower soil strata without any excessive settlements.
If the foundation of the building is placed without understanding the ground conditions below, it may lead to the failure of foundation. Once the failure of foundation has took place, very little can be done to improve the situation.
Foundation are of two types:- deep and shallow.
Deep Foundation:- Deep foundation are employed where the soil immediately below the structure with in reasonable depth is not capable of supporting the load of the building.
The deep foundation may be classified as: (1) Deep Footing, (2) Pile Foundation, (3) Pier Foundation, (4) Well Foundation.
Shallow Foundation:- According to Terzaghi, a foundation is shallow if its depth is equal to or less than its width and deep foundation if the depth of foundation is greater than its width.
The Shallow foundation may be classified as: (1) Strip Footing, (2) Spread Footing, (3) Isolated Footing, (4) Stepped Footing, (5) Combine Footing, (6) Strap Footing, (7) Raft Foundation.
Isolated Footing:- Isolated footing is the most common type of foundation used for building contruction. In small construction we use isolated footing.
In this footing planning, we use isolated 3'-6"x3'-6" square footing.