It is critical to choose the right type of foundation for buildings construction. It’s considered the main part of civil engineering, as it’s one of the most important elements of any project. It is the lower part of any building construction that provides it with strength to hold the construction over time.
What is the foundation for buildings?
The foundation for building construction is the main component that supports any building structure.
It’s the base level of the construction, which is in direct contact with soil, that holds the moisture and groundwater away from the structure and distributes the structure’s weight through the ground to hold the construction withstand safely.
Importance of Foundations in Construction:
A well-chosen type of foundation for building construction holds the entire structure, so it needs to be correctly formed with the highest quality and validity as it needs to keep the rest of the house upright; therefore, you should invest suitably at this stage to avoid any damages from the beginning of the construction process.
A strong foundation for building construction avoids compound defects that detect the efficacy of the rest of the building’s construction. For example, if a foundation provides an unleveled surface to build on, this should be enhanced as the structure continues to be built upward.
A poor type of foundation for building construction creates a domino effect for other parts of its construction, and without its acting as a stable and strong starting point, compounding defects will happen due to the issues caused by an insufficient foundation, which cannot be corrected after finishing the construction.
The foundation for building construction prevents overloading by distributing the weight of the building far into the ground.
It offers adaptability and structural stability, prevents unequal settlement, and prevents lateral movement in the building, which helps avoid overloading other parts of the structure.
How many types of foundations for building construction?
Different types of foundation in construction are found, each suitable for a different construction project. It can be detected by surveying the soil before deciding the required for the building, as the ground conditions have an important part to play, by digging holes deeply at different points across the area and using the results to assume the conditions throughout.
Foundations for building construction are classified into two major types: shallow and deep foundations. Each of them consists of minor types;
- The shallow types of foundation for buildings construction consist of:
- Individual footing or isolated footing.
- Combined footing.
- Wall or strip footing.
- Raft or mat foundation.
- The deep types of foundation for buildings construction consist of:
- Pile foundation.
- Drilled shafts or caissons.
What are the types of foundation in building construction?
There are many types of foundation for buildings in civil engineering:
Shallow type of foundations:
Shallow foundation is one of the types of foundation for buildings , is used when the founding depth (Df) is less than the width of the footing and less than 3 m that is found close to the ground surface, and they are also used if surface loading or other surface conditions will affect the bearing capacity of a foundation. Used for light to medium-weight structures.
Shallow foundations are commonly used because they are cheaper, economical, and relatively easy to construct.
There are 4 minor shallow types of foundation for buildings construction:
Shallow foundations include individual footings or isolated spread footings, combined footings, wall or strip footings, and raft or mat foundations. These four shallow foundation types can be further classified as follows:
1. Individual footing or isolated footing:
Individual footing, or an isolated footing, is used to support individual columns; it is considered the most common and economical type of foundation used widely for ordinary building construction. Each column in the structure has its own isolated footing that directly distributes the load all over the ground soil.
It can be found in a square shape or rectangle; the shape is selected based on the load on the column and the bearing capacity of the soil. Rectangular isolated footing is selected when the foundation is facing loads of deflection or due to horizontal forces.
There are three basic criteria that should be found in this foundation type: it should be aligned correctly in both the vertical and horizontal directions, should be able to solve the poor capacity of soil, and should support the strength of construction.
2. Combined footing:
A combined footing is a combination of isolated footings with a difference in their design. It consists of two or more closed, adjacent columns that may overlap each other. The common shape of this footing is a rectangle, which spreads the load between the columns and prevents overloading, thus creating a continuous support system for the building foundation.
3. Wall or strip footing:
A strip footing is used for load-bearing walls, as in footings for house extensions. It is about a row of closely spaced columns. The wider base of this foundation type distributes the load over a wider area, but the soil-bearing capacity should be sufficient to provide better stability to the construction.
The size and position of the strip footing are detected according to the overall width of the wall.
They are particularly used for light structural loads such as those found in low-rise or medium-rise domestic buildings.
4. Raft or mat foundation:
Raft or mat foundation consists of large continuous rectangular or circular columns and walls that distribute the load over the area of the construction ground.
It can reduce the differential settlement when the soil layer has low bearing capacity or when the superstructure load is distributed extensively throughout the ground, and it also shouldn’t be used where the groundwater table is above the bearing surface of the soil because using it in this condition may cause liquefaction.
Mat foundations are common in commercial building projects and basements.
Deep type of foundations:
A deep foundation is one of the types of foundation for buildings construction is used when the depth from the superstructure to the underside of the foundation exceeds five times the width of the foundation. However, it is used where the bearing capacity of the soil is poor, there are large design loads, and there are site constraints.
The construction process of a deep foundation is more complex and expensive than shallow foundations.
There are 2 minor deep types of foundation for building construction:
1. Pile foundations:
Pile foundations look like long, slender structural columns called piles.
These piles are pushed deeply into the ground to transfer the heavy loads of the structure to stronger, more stable soil and hard rock layers below the ground level, and this depth is about 5m to 50m (15 feet to 150 feet) deep from the ground level.
This is also used to prevent the destruction of the structure due to lateral loads such as earthquakes and wind forces.
Pile foundation’s columns made of strong materials include concrete and steel. Whereas steel reaches greater depths and is suitable for heavier loads but may cost more and corrode over time. Wood foundations are cheaper and available but can’t always penetrate hard soil.
2. Drilled shafts or caisson foundations:
Drilled shafts, also called caissons, are types of deep foundations done using an auger.
It has the same function as pile foundations, which have been discussed above, but caissons are rigid with a high capacity cast for deep building foundations.
By its shaft resistance, toe resistance, and/or combination of them, it can support the structure with large axial and lateral loads so that it can resist loads from it by drilling cylindrical shafts into the ground, then filling them with concrete to form a watertight structure designed for bridges, concrete dams, ship repairs, and other large structures.
Drilled shafts can push column loads deeper than pile foundations. It is used when the depth is within 10 m to 100 m (25 feet to 300 feet) below ground.
What are the uses of each foundation type?
There are many different usages for the types of foundation for buildings as following:
- Shallow foundations are the most common type used to handle the weight distribution for small, light buildings and domestic projects. Where the depth of these is generally less than their width (less than six feet) and the earth below it has sufficient weight-bearing capacity, a shallow foundation may fit, and this makes them both cheaper and faster to build.
For example:- Residential homes and wooden structures.
- Deep foundations are used to carry the load of the structure through the weak soil to the stronger soil or rock below to provide a stable base in this soft or weak soil that cannot support the weight of the building.
For example:- Taller commercial or residential buildings.
- Heavy buildings like skyscrapers and shopping centers.
- Bridges, piers, and dams due to the strength of deep foundations that makes them fit in water environments, where they provide strong support to it.
