Details of Foundation Construction
Foundation belongs to the portion of structure that is built under plinth level and extends up to the soil. It touches the soil directly and delivers the load of super structure to soil. Normally it is developed under the ground level. In case, some portion of foundation is over ground level, earth filling is applied to cover it. This part of the structure does not have any connection with air, light etc, or alternatively it can be described as the hidden part of the structure.
Depth of Foundation
Depth of foundation is based on the following aspects.
1. Accessibility of sufficient bearing capacity
2. Depth of shrinkage and swelling for clayey soils, because of periodic changes appreciable movements may occur.
3. Depth of frost penetration for fine sand and silt.
4. Chance for closing of excavation
5. Depth of ground water table
6. Practical minimum depth of foundation should have been up to 50 cm. and not below to facilitate elimination of top soil and variations in ground level.
7. Therefore, as per suggestion, the depth of foundation should be varied from 1.00 meter to 1.5 meter from original ground level.
Footing stands for a structure that is built up in brick work, masonry or concrete beneath the base of a wall or column with the purpose of dispersing the load across a wide area.
Width of Foundation/ Footings
On the basis of the structural design, the width of footings should have been placed. For the buildings which contain light load like houses, flats, school buildings etc constructed with two stories, the width of foundation should be as follow :-
1. The width of footing should not be under 75 cm toward one brick thick wall.
2. The width of footing should not be under 1 meter toward one and half brick wall.
Various Foundation Work Methods
The methods employed in the foundation works are as follow :-
1. Excavation of earth work in trenches for foundation.
2. Arrangement of cement concrete.
3. Placing the footing for raft or column construction.
4. Setting of Anti termite treatment.
5. Placing Brick work up to plinth level.
6. Placing Damp proof course on the walls.
7. Refilling of earth around the walls
8. Refilling of earth in the part of the building up to the requisite height consistent with plinth level.
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