Foundations are generally divided into deep and shallow foundation types. If a building to be constructed is intended to extend vertically the deep foundation type should be used.
If the soil type on the site is weak, that would automatically require a deep foundation type to be used. Stones, steel, concrete, and steel are the materials that are used to construct the building. the selection of which material and foundation type to be used on the proposed structure is determined by the type of the underlying soil and the design loads.
Below are the different types of foundations;
- Shallow foundation types
Strip foundation
Individual footing
Combined footing
Raft foundation
2 . Deep foundation types
Pile foundation
Drilled shafts
Requirements of a good foundation
- Sustain loads- a good foundation should be designed and constructed in a way that it can be able to bear, sustain and transmit the dead and imposed loads to the ground.
- Have a rigid base-a good foundation should have a rigid base to avoid differential settlements in situations where the superimposed loads are not uniform.
- Great location- a good foundation should be located in a place where it will not be affected in future
- Should be deep– Also, a good foundation should be deeper to protect it from any damage caused by shrinkage and swelling
Functions of a foundation
- Distributing loads-to distribute and transfer the total weight of the dead and imposed loads of the structure to a stratum in the ground for support.
- Provide stability-to provide the constructed structure with stability.
- Prevent settlement-to prevent differential settlement of the structure.
- Prevent lateral movement-To prevent lateral movement of the constructed structure.
- Provide even surface-to provide an even surface firm bed for the development of the superstructure.
- Prevent natural disasters-to prevent the structure from natural disasters like earthquakes and their effects
Cost of building a foundation for a residential house in Kenya
Generally constructing a good foundation in Kenya will cost you about Ksh 56000-200000
However, this cost will vary depending on the following factors.
- The type of house to be constructed– a storey building will cost more than a regular bungalow building because it will require a deeper foundation which then translates to more materials being used to construct it.
- Type of soil-the type of soil on site affects the cost of the foundation, in the event of red soil it will be less expensive compared to the case of black cotton soil which has to be dug out and removed to access the rock.
- Drainage of the site-constructing a house in a swampy area will cost more compared to a dryer area since you have to do draining and land reclamation which comes at an extra cost.
- Size of the house -the more square meter coverage of the house, definitely the more materials are used to construct the foundation therefore the more expensive it is.
- Location-location of the site directly affects the cost of foundation construction, urban areas and the environs attract higher rates compared to rural places.
- Mechanization-using machines in the construction of the foundation will cost you more because of the cost of hiring the machines and mobilization.
Conclusion
It is important to have a good and strong foundation because it determines the overall stability of the structure. With the above guide, you can now make a sound decision on what type of foundation you prefer to use for your residential home keeping in mind all the discussed factors above.
