Introduction:
A foundation is the most important element or structure of a building.
This is simply because it's the part of the building which essentially supports the weight of the building.
It's selection is based on the type of the building being constructed, as well as the type of soil present on the land in which the proposed construction of the building is being planned.It's extremely important that the right foundation is done for a proposed building, otherwise the building could easily collapse if the foundation is not able to support the weight of the building, thereby putting lives of occupants of the building at risk.
There is also the impact of the huge financial losses which could happen due to the collapse of a building.
So, how exactly do we define foundation?
Definition:
A foundation can simply be defined as the element of a structure/building which connects it to the ground, and transfers load from the structure to the ground.
Types of Foundation
a) Shallow foundation
b) Deep foundation
Shallow Foundation types:
a) Individual/Isolated footing
b) Combined footing
c) Spread/Strip foundation
d) Raft/Mat foundation
I will briefly explain each of these foundation types...
a) Individual/Isolated footing:
This is the most common type of foundation used for building construction.
It is also known as pad foundation.
This type of foundation is constructed for single columns & it's used when loads from the structure is carried by the columns.
The shape of individual footings is square or rectangular.
The soil type comes to play in the construction of individual footings as the size of the foundation is calculated based on the load on the column and the safe bearing capacity of the soil.
b) Combined footing:
This type of foundation is also used when loads from the structure is carried by the columns.
It is usually recommended when there are 2 or more columns in the building which are close to each other.
It's simply a combination of individual footings, but their structural design differs. The shape of this type of foundation is rectangular.
c) Spread/Strip footings:
The base of this type of foundation is wider than a typical individual footing or combined footing. This helps to provide better stability for the building by spreading the weight of the building over a wider area.
It's usually used on lands where the soil bearing layer is within 3metres(or 10feet) from the ground's surface, thus helping to provide a better stability & support for the building.
It's obvious thus that the type of soil on a land plays a crucial role in the selection of a foundation which will be suitable for the building being proposed.
d) Raft/Mat foundation:
This type of foundation is increasingly being used nowadays in construction.
This foundation is spread across the entire area of the building in order to better support heavy structural loads from columns & walls, especially where the loads from the structure is expected to be very high.
It is suitable for soil types whose bearing capacity is less suitable for individual footings or combined footings, as it effectively carries the weight of the building much better since the foundation is spread over the entire area of the building.
This topic will be continued next week as I talk about deep foundations and it's different types.
Stay tuned!!
Dr. B.A. Oyeneyin
M.B.CH.B., A.C.S., A.C.S.I.(UK)
Medical doctor, Associate Chartered Stockbroker, Certified financial/investment analyst & Real estate consultant.
