One of the most important decisions to be made while building a house, is selecting the right foundation.
The right foundation ensures the structural stability, safety, and longevity of your house.
Below is a quick guide on how to select the right foundation;
Know why you need a strong foundation
Most people don’t know why a foundation is a critical element in a building. Worse still, some think that you can just copy paste from what you saw a friend use for their project.
The foundation supports the entire structure, distributing the load evenly to the ground. A well-designed foundation prevents structural damage, uneven settling, and water infiltration
Conduct a site investigation
The use of various foundations depends on the site factors such as type of the soil, the climate of the area in which the site is located, the local topography, and final the water table level.
Consider durability and Maintenance
Some materials such as concrete, bricks and stones are more durable options. There is also the need to use steel reinforcement in highly loaded buildings. In areas where the site is sloppy or the water table is high, there is need to consider use of French drains and retaining walls.
Know your budget and timelines
Some foundations are more expensive than others. Additionally, other foundations take longer to build.
Consult Building professionals
You need to engage structural Engineers for precise load calculations and soil assessment. You will also need to engage an experienced contractor to ensure proper execution of the design.
Plan for Future Needs
Think about potential additions or renovations. Consider energy efficiency and insulation options.
Prioritize Sustainability
Use eco-friendly materials like recycled aggregates. Plan for efficient drainage to avoid groundwater contamination.
THE DIFFERENT TYPES OF FOUNDATIONS TO CONSIDER
There are various types of foundations depending on your site conditions as highlighted below;
Raft Foundation
It is also known as a mat foundation. It is basically a thickened reinforced concrete slab, spread over a large area of soil. The slab provides supports for columns and several load bearing walls.
Areas supporting the heavy columns and walls within the slab are thickened. The foundation can also have beams between columns, to provide stiffness to the raft.
It is best used in areas where the soil bearing capacity is low or when the columns are very close to one another.
The main merit of this type of foundation is that it distributes load evenly, and thus minimizes settlement issues. The slab is cost effective as the raft can be used as the ground floor. Additionally, there is no need for deep foundations.
Strip Foundations
Strip foundations, also known as strip footings, are a type of shallow foundation commonly used for buildings with load-bearing walls. They consist of continuous strips of concrete (or other material) laid under walls to distribute the load evenly over the ground.
They are the most commonly used for majority of buildings in Kenya.
Ideal for areas with stable soils, and when the intent is to construct a residential house or a low rise apartment.
Main advantage is that they are cost effective and work well for long linear walls commonly used in residential buildings.
Pile foundations
Pile foundations are a type of deep foundation used to transfer the load of a structure through weak or compressible soil layers to a more stable and strong stratum deep underground.
These foundations consist of long, slender columns made of concrete, steel, wood, or composite materials, driven or drilled into the ground.
At the top of the pile is a slab known as a pile cap that can be used as ground floor slab.
An example of a building where pile foundation was used was the University of Nairobi Towers.
Suitable for areas with extremely weak soil. They are ideal for very high rise buildings such as skyscrapers, bridges, docks, flyovers, etc.
Shaft Foundations
Shaft foundations are a type of deep foundation that transfers the load of a structure to a deep, stable stratum.
They are constructed by drilling a cylindrical hole into the ground, reinforcing it with steel, and filling it with concrete.
Unlike pile foundations, drilled shafts are typically larger in diameter and can support higher loads.
Advantages of using a shaft foundation are that it can handle very large loads due to their size and depth. They are also customizable to fit specific site conditions. They also tend to have minimal noise and vibrations during construction thus making them suitable for urban areas or sensitive locations. They have a reduced Settlement, even in soft soils. They are also very durable:
The main demerit is that they tend to be very expensive to build and maintain.
Pad Foundations
Pad foundations are a type of shallow foundation used to transfer and distribute structural loads from columns or walls to the ground.
They are typically used for structures where the soil has sufficient load-bearing capacity near the surface and are economical compared to other foundation types like pile or raft foundations.
They are used in Low-rise buildings, light industrial structures, residential houses, areas with good soil conditions and low ground movement risks
From the list of shaft, piles, raft and strip foundations, a potential home builder has a wide range of foundations to suit different needs. It is strongly advised that before you decide on either of the foundations, seek professional advice from an engineer on the design and a quantity surveyor on the arising costs.
The right foundation ensures the structural stability, safety, and longevity of your house.
Below is a quick guide on how to select the right foundation;
Know why you need a strong foundation
Most people don’t know why a foundation is a critical element in a building. Worse still, some think that you can just copy paste from what you saw a friend use for their project.
The foundation supports the entire structure, distributing the load evenly to the ground. A well-designed foundation prevents structural damage, uneven settling, and water infiltration
Conduct a site investigation
The use of various foundations depends on the site factors such as type of the soil, the climate of the area in which the site is located, the local topography, and final the water table level.
Consider durability and Maintenance
Some materials such as concrete, bricks and stones are more durable options. There is also the need to use steel reinforcement in highly loaded buildings. In areas where the site is sloppy or the water table is high, there is need to consider use of French drains and retaining walls.
Know your budget and timelines
Some foundations are more expensive than others. Additionally, other foundations take longer to build.
Consult Building professionals
You need to engage structural Engineers for precise load calculations and soil assessment. You will also need to engage an experienced contractor to ensure proper execution of the design.
Plan for Future Needs
Think about potential additions or renovations. Consider energy efficiency and insulation options.
Prioritize Sustainability
Use eco-friendly materials like recycled aggregates. Plan for efficient drainage to avoid groundwater contamination.
THE DIFFERENT TYPES OF FOUNDATIONS TO CONSIDER
There are various types of foundations depending on your site conditions as highlighted below;
Raft Foundation
It is also known as a mat foundation. It is basically a thickened reinforced concrete slab, spread over a large area of soil. The slab provides supports for columns and several load bearing walls.
Areas supporting the heavy columns and walls within the slab are thickened. The foundation can also have beams between columns, to provide stiffness to the raft.
It is best used in areas where the soil bearing capacity is low or when the columns are very close to one another.
The main merit of this type of foundation is that it distributes load evenly, and thus minimizes settlement issues. The slab is cost effective as the raft can be used as the ground floor. Additionally, there is no need for deep foundations.
Strip Foundations
Strip foundations, also known as strip footings, are a type of shallow foundation commonly used for buildings with load-bearing walls. They consist of continuous strips of concrete (or other material) laid under walls to distribute the load evenly over the ground.
They are the most commonly used for majority of buildings in Kenya.
Ideal for areas with stable soils, and when the intent is to construct a residential house or a low rise apartment.
Main advantage is that they are cost effective and work well for long linear walls commonly used in residential buildings.
Pile foundations
Pile foundations are a type of deep foundation used to transfer the load of a structure through weak or compressible soil layers to a more stable and strong stratum deep underground.
These foundations consist of long, slender columns made of concrete, steel, wood, or composite materials, driven or drilled into the ground.
At the top of the pile is a slab known as a pile cap that can be used as ground floor slab.
An example of a building where pile foundation was used was the University of Nairobi Towers.
Suitable for areas with extremely weak soil. They are ideal for very high rise buildings such as skyscrapers, bridges, docks, flyovers, etc.
Shaft Foundations
Shaft foundations are a type of deep foundation that transfers the load of a structure to a deep, stable stratum.
They are constructed by drilling a cylindrical hole into the ground, reinforcing it with steel, and filling it with concrete.
Unlike pile foundations, drilled shafts are typically larger in diameter and can support higher loads.
Advantages of using a shaft foundation are that it can handle very large loads due to their size and depth. They are also customizable to fit specific site conditions. They also tend to have minimal noise and vibrations during construction thus making them suitable for urban areas or sensitive locations. They have a reduced Settlement, even in soft soils. They are also very durable:
The main demerit is that they tend to be very expensive to build and maintain.
Pad Foundations
Pad foundations are a type of shallow foundation used to transfer and distribute structural loads from columns or walls to the ground.
They are typically used for structures where the soil has sufficient load-bearing capacity near the surface and are economical compared to other foundation types like pile or raft foundations.
They are used in Low-rise buildings, light industrial structures, residential houses, areas with good soil conditions and low ground movement risks
From the list of shaft, piles, raft and strip foundations, a potential home builder has a wide range of foundations to suit different needs. It is strongly advised that before you decide on either of the foundations, seek professional advice from an engineer on the design and a quantity surveyor on the arising costs.
