The foundation is the lowest part of a building which bears the load of the structure. It is the element of architectural structure which connects the building to the ground and transfers loads from the structure to the ground. Determining the type of foundation depends on the soil property and the proposed bearing load. The bearing load is the total static and dynamic load of the structure. The static load is the resultant load of the structure itself while the dynamic load is the load from activities done on the structure, e.g., the weight of people in a building.
It is important to know the types of foundation before deciding on the type to use. There are two major types of foundation with unique application to each. The major types of foundation are the shallow and deep foundations.
Shallow foundation: A shallow foundation is a type of building foundation that transfers building loads to the earth close to the surface. This type of foundation is used for light structure. This foundation takes moderate weight with few column and pillars. Bungalow, warehouses, flats use this type of foundation. Furthermore, shallow foundation is divided into subdivisions based on their load bearing orientations. They are:
- Pad foundation: The pad foundation carries and spreads concentrated loads to the soil from superstructures and transfers point loads through the column or framed structures. It also transfers point load from concrete blocks and pads which are usually placed at shallow depth. These pads may be of square, rectangular or circular shape which distribute the loads from the structure to the bearing layer of soil. This type of foundation can be used for strong or weak soil. The soil is stabilized before applying pads when used on weak soil. This foundation is suitable for buildings with low superstructure loads such as workshops, warehouse and framed structures.
- Strip foundation: This type of shallow foundation is used to provide a continuous, level strip of support to linear structure. It acts as a long strip to support the weight of the entire wall. Strip foundation is common in buildings with long bearing wall transmitting load from the roof down to the foundation. This is preferred in strong soil type and for residential buildings like bungalow. In case of story buildings on a strong soil, both stripe and pad foundation is used.
- Raft or mat foundation: This is a continuous slab resting on the soil extending over the entire footprint of the building for support and transferring of its weight to the ground. It allows the spread of load over a large area. This is most suitable in waterlogged or swampy area. It is also used in strong soil area for basement floor. This type of foundation is recommended for storey buildings on weak soil.
Deep foundation: This type of foundation transfers building loads to the earth farther down from the surface than a shallow foundation does to a subsurface layer or a range of distance. This is majorly determined by the strength of the soil on which of the foundation is to be erected. The major type of deep foundation is pile foundation which also has subdivisions which are:
- End Pile foundation: This foundation is used to transfer loads from the superstructures through weak strata of soil to strong soil at depth. It is basically a cylindrical steel which is placed so that the bottom end of the pile rests on layer of strong soil or rock for transfer of load.
- Friction pile foundation: This type of foundation transfers the load of the structure to the soil across the full height of the pile due to the frictional force developed by the surrounding soil. The entire surface of the pile, which is cylindrical in shape, works to transfer the forces to the soil.
Proper project management entails using the best foundation with consideration of the soil type and the load. Consult Luvanex Builds on your building project.