Different types of footing foundations are used in building construction. It depends on soil condition and loads from the structure. Footing is structural elements that transmit to the soil column loads, wall loads or lateral loads. It is advisable to know suitability of each types of foundation before making any decision for their selection in any type construction project.
Wall footing is used to support structural walls that carry loads for other floors or to support nonstructural
Isolated footing or Single footing
Isolated footing is used to support single columns. Isolated footing is one of the most-popular and simplest types of foundation used worldwide. This is one of the most economical types of footings and is used when columns are spaced at relatively long distances.
Combined footings usually support two columns, or three columns not in a row. Combined footings are used when two columns are so close that single footings cannot be used or when one column is located at or near a property line.
Cantilever footings or strap footings
Cantilever consist of two single footings connected with a beam or a strap and support two single columns. This
type replaces a combined footing and is more economical.
Continuous footings support a row of three or more columns. They have limited width and continue under all columns.
Rafted or mat foundation
Rafted or mat foundation consists of one footing usually placed under the entire building area. They are used, when soil bearing capacity is low, column loads are heavy single footings cannot be used, piles are not used and differential settlement must be reduced.
Pile caps are thick slabs used to tie a group of piles together to support and transmit column loads to the piles.
The cost of footings as compared to entire R.C.C. framed structure is less and is about 4 to 5% of the total building can only. Hence one should not economical foundation also pad footings are preferred, though increase cost marginally.