Updated November 4th, 2019
Basically, there are two types of foundations are used in building construction. One is the Shallow foundation and another is the Deep foundation.
These two types of foundations can be classified into some other types.
From this post, you’ll learn about all the types of foundations used in building construction along with their basic details.
Before that, let’s discuss a little about the foundation.
What Is The Foundation?
The foundation is a structural part of a building on which a building stands.
It transmits and distributes its own load as well as imposed loads to the soil in such a way that the load-bearing capacity of the foundation bed is not exceeded.
The solid ground on which the foundation rests is called foundation bed.
Types Of Foundation In Building Construction
As I said at the beginning of this post, Foundation is basically two types – Shallow and Deep.
A shallow foundation is a type of foundation that transfers loads to the very near the surface.
Shallow foundations typically have a depth to width ratio of less than 1.
And the depth of the foundation bed is normally less than five times the width of the foundation.
Generally, the depth of the foundation bed of shallow foundation doesn’t exceed 5 meters.
A more common depth of foundation bed is below 3 meters from the surface.
Types Of Shallow Foundation
Following types of shallow foundations are used in building construction:
Let’s discuss these types of shallow foundations.
- Isolated Footing:
An isolated footing normally supports a column of a building. This is the most economical footing.
They are usually in square or rectangle shape with the column sitting in the middle of the footing.
This footing is also known as individual footing or pad footing.
- Combined Footing:
A footing, either rectangular or trapezoidal, that supports two columns is called combined footing.
- Cantilever Or Strap Footing:
Consist of two single footings connected with a beam or a strap and support two single columns.
This footing is also called spread footing.
- Mat Or Raft Footing:
Consist of one footing usually placed under the entire building area.
They are used when:
-soil bearing capacity is low,
-column loads are heavy,
-single footing can’t be used,
-piles are not used, and
-the differential settlement must be reduced.
- Wall Footing:
Wall footings are used to distribute loads of structural load-bearing walls to the soil.
Deep foundations are those founding too deep below the ground surface for their base bearing capacity to be affected by surface conditions, this is usually at depths of not less than 3 meters below ground level.
This type of foundation can be used to transfer the load to a deeper, more competent strata at depth if unsuitable soils are present near the surface.
Types of Deep Foundations:
Pile foundations are a common type of deep foundation.
These are relatively long, slender members that transmit foundation loads through soil strata of low bearing capacity to deeper soil or rock strata having a high bearing capacity.
They are used when for economic, constructional or soil condition considerations. It is desirable to transmit loads to strata beyond the practical reach of shallow foundations.
In addition to supporting structures, piles are also used to anchor structures against uplift forces and to assist structures in resisting lateral and overturning forces.
Thick slabs are used to tie a group of piles together to support and transmit column loads to the piles. This slab is called a pile cap.
Fundamentally, pile foundations are two types – End bearing pile and Friction pile.
- End Bearing Piles:
The principal of this type of pile is, the bottom end of the pile is rest on the hard layer, mainly in the intersection of the weak and the hard layer.
And this pile transfers loads of the structure through it to the hard layer and thus it bypasses the weak soil layer.
So, basically it acts like a column.
- Friction Piles:
Friction piles are completely different than the End bearing piles.
End bearing piles normally transfer loads through its bottom end whereas fiction piles do it across its full length, by friction.
That means the entire surface of the friction pile works to transfer loads to the soil.
So, we can say, the longer a friction pile, the more amount of loads it can support.
As a construction professional, you just need to know about the types of foundations used in building construction.
It is the structural designers’ responsibility to select which type of foundation should be used in what conditions.
In this article, I’ve discussed all types of foundations used in building construction. You might have heard some other names of foundation. It is very possible that that is a different name of any of the types I’ve discussed here.
So don’t be confused with the name of foundations. Someone in some countries may be called the same foundation with different names.
Editor’s Note: This post was originally published in Jun 2011 and has been completely revamped and updated for accuracy and comprehensiveness.
Have you heard any names of the types of foundation other than I’ve discussed in this post? Please share in the comments below…
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