10 Types of Foundations in Constructions with Their Uses – PDF

Different types of foundations used in house or building construction are shallow foundations such as isolated footing, combined footing, strip foundation, Raft or mat foundation, and deep foundations such as pile foundation, pier foundation, and drilled shafts or caissons.

It is advisable to know the uses and suitability of these types of foundations before their selection for a construction project.

Types of Foundations and Their Uses

The following are different types of foundations used in construction:

1. Shallow foundation
   • Individual footing or isolated footing
   • Combined footing
   • Strip foundation
   • Raft or mat foundation
2. Deep Foundation
   • Pile foundation
   • Pier Foundation
   • Drilled Shafts or caissons

Types of Shallow Foundations

1. Individual Footing or Isolated Footing

Individual footing or an isolated footing is the most common and economic foundation used for building construction. This foundation is constructed for a single column called a pad foundation.

Isolated footings are typically used for shallow buildings and structures to convey and spread concentrated loads by pillars or columns. They are generally used for ordinary buildings (Typically up to five stories).

The shapes of isolated or individual footing are either square or rectangular. The size of such foundations is calculated based on the load on the column and the safe bearing capacity of the soil.

Rectangular isolated footing is selected when the foundation experiences moments due to the eccentricity of loads or due to horizontal forces.

For example, consider a column with a vertical load of 300 kN and a safe bearing capacity of soil as 100 kN/m^{2. Then} the area of the footing required will be 300/100 = 3m2. So, for a square footing, the length and width of the footing will be 1.732 m x 1.732 m, and the length and width of the footing for a rectangular shape can be 1.5 m x 2 m.

The followings are the types of Isolated footing:

1. Single pad footing
2. Stepped footing for a column
3. Sloped footing for a column
4. Wall footing without step
5. Stepped footing for walls
6. Grillage foundation

Isolated foundations are economical to use when:

The load of the structure is relatively low.
Columns are not closely placed.
The bearing capacity of the soil is high at a shallow depth.

2. Combined Footing

A combined footing is constructed when two or more columns are close enough, and their isolated footings overlap due to the closed placement of columns or due to the low bearing capacity of the soil. It is a combination of isolated footings, but their structural design differs.

The shape of this footing is a rectangle and is used when the columns carry loads from the structure.

There are different types of combined footings, such as

1. Slab type,
2. Slab and beam type,
3. Rectangular,
4. Raft, and
5. Strap beam type.

They may be square, tee-shaped, or trapezoidal.

The main objective of the combined footing is the uniform distribution of loads under the entire footing area.

3. Spread Footings or Strip Footings and Wall Footings

Spread footings, also known as continuous footings, are those whose base is wider than a typical load-bearing wall foundation. The wider base of this type of footing distributes loads of structural or non-structural load-bearing walls to the ground in such a way that the load-bearing limit of the soil isn’t outperformed and provides better stability.

These footings run along the direction of the wall. The width of the wall foundation is usually 2-3 times the width of the wall.

Spread and wall footings are used for individual columns, walls, and bridge piers where the bearing soil layer is within 3m (10 feet) from the ground surface. Soil-bearing capacity must be sufficient to support the structure’s weight over the base area of the structure.

These should not be used on soils where there is any possibility of a ground flow of water above the bearing layer of soil, which may result in scour or liquefaction.

A wall footing is a continuous slab strip along the length of the wall. Stone, brick, reinforced concrete, etc., are used for the construction of wall foundations.

• On account of block walls, the footing comprises a few courses of bricks, the least course being generally double the expansiveness of the wall above.
• For the masonry walls, the counterbalances could be 15 cm, with the statues of the course as 30 cm. Along these lines, the size of the footings is marginally more than that of the block divider footings.
• If the heap on the wall is substantial or the soil is of a low bearing capacity, the reinforced concrete foundation type can be given.

Wall footings are economical when:

• Loads to be transmitted are of small magnitude.
• It is placed on dense sand and gravel.

Benefits of strip foundation:

• A Strip foundation is a cost-effective and efficient solution for low-rise buildings with relatively small loads.
• It is easy to construct and requires minimal excavation, which can save time and money during construction.
• Strip foundation is suitable for a wide range of soil types, including cohesive and non-cohesive soils.

Disadvantages of strip foundation:

• Strip foundations may not be suitable for buildings with high loads or unstable soil conditions.
• It can be vulnerable to differential settlement, which can cause cracks and other damage to the building.
• The Strip foundation may require additional reinforcement or underpinning if the soil conditions are not suitable.

Applications of strip foundation:

• Strip foundation is commonly used in the construction of residential and commercial buildings with relatively small loads.
• It is also suitable for constructing walls, retaining structures, and other non-load-bearing elements.

Examples of construction projects that use strip foundations:

• The Burj Khalifa, the tallest building in the world, uses strip foundations to distribute the load of the building evenly across the ground.
• The Shard, a skyscraper in London, also uses strip foundations to support the weight of the building.
• Strip foundation is also commonly used in the construction of single-family homes and small commercial buildings.

4. Raft or Mat Foundations

Raft or mat foundations are the types of foundations that are spread across the entire area of the building to support heavy structural loads from columns and walls. It consists of a reinforced concrete slab that extends over the entire area of the building and is supported by a grid of reinforced concrete beams.

The use of mat foundation is for columns and walls foundations where the loads from the structure on columns and walls are very high, and other shallow or pile foundations are not suitable.

This is used to prevent differential settlement of individual footings, thus designed as a single mat (or combined footing) of all the load-bearing elements of the structure.

It is suitable for expansive soils whose bearing capacity is less than the suitability of spread footings and wall footings and the load of the structure is to be distributed over a large area or structure is subjected continuously to shocks or jerks.

A raft foundation is economical when the one-half area of the structure is covered with individual footings and wall footings are provided.

These foundations should not be used where the groundwater table is above the bearing surface of the soil. The use of foundation in such conditions may lead to scouring and liquefaction.

A raft foundation consists of a reinforced concrete slab or T-beam slab placed over the entire area of the structure. In this type, the whole basement floor slab acts as the foundation. The total load of the structure is spread evenly over the entire area of the structure.

This is called a raft because, in this case, the building seems like a vessel that floats on a sea of soil.

Raft foundations are economical when:

1. The soil is weak, and the load has to be spread over a large area.
2. The structure includes a basement.
3. Columns are closely placed.
4. Other kinds of foundations are not feasible.
5. Differential settlement is to be prevented.

Benefits of the raft foundation

• Raft foundation is suitable for buildings with large loads or poor soil conditions, as it can distribute the load evenly and reduce the risk of differential settlement.
• It is less vulnerable to the effects of shrinkage and swelling of the soil, which can cause cracks in the building.
• Raft foundation can be designed to incorporate insulation and other features that can improve the energy efficiency of the building.

Disadvantages of raft foundation

• Raft foundation can be more expensive than other types of shallow foundation due to the amount of concrete and steel required.
• It may require more excavation and preparation work than other types of foundation.
• Raft foundation may not be suitable for sites with high water tables, as the water can undermine the foundation and cause instability.

Applications of raft foundation

• Raft foundation is commonly used in the construction of multi-story buildings, such as apartments and offices.
• It is also suitable for buildings with irregular or unusual shapes, as it can be designed to fit the specific requirements of the building.

Examples of construction projects that use raft foundation

• The Burj Al Arab, a luxury hotel in Dubai, uses raft foundation to support the weight of the building and its distinctive sail-shaped structure.
• The Shard, a skyscraper in London, also uses raft foundation to support its towering height and the weight of the building.
• Raft foundation is also commonly used in the construction of large commercial buildings, such as shopping centers and hospitals.

Types of Deep Foundation

5. Pile Foundations

A pile foundation is a type of deep foundation used to support heavy loads or when the soil conditions at the surface are not suitable for shallow foundations. It is used to transfer heavy loads from the structure to hard rock strata much deep below the ground level. It consists of long, slender columns made of concrete, steel, or wood, which are driven or drilled into the ground to support the load of the building.

Pile foundations transfer heavy loads of structures through columns to hard soil strata, which are much below ground level, where shallow foundations such as spread footings and mat footings cannot be used or may not be economical.

This is also used to prevent the uplift of the structure due to lateral loads such as earthquakes and wind forces.

Pile foundations are generally used for soils where soil conditions near the ground surface are not suitable for heavy loads. The depth of hard rock strata is maybe 5m to 50m (15 feet to 150 feet) deep from the ground surface.

Pile foundation resists the loads from the structure by skin friction and by end bearing. The use of pile foundations also prevents differential settlement of foundations.

The followings are the types of pile foundations:

1. Based on Function or Use
   1. Sheet Piles
   2. Load Bearing Piles
   3. End Bearing Piles
   4. Friction Piles
   5. Soil Compactor Piles
2. Based on Materials and Construction Method
   1. Timber Piles
   2. Concrete Piles
   3. Steel Piles
   4. Composite Piles

Pile foundations are economical when:

• Soil with great bearing capacity is at a greater depth
• When there are chances of construction of irrigation canals in the nearby area
• When it is very expensive to provide raft or grillage
• When the foundation is subjected to a heavily concentrated load
• In marshy places
• When the topsoil layer is compressible in nature
• In the case of bridges, when the scouring is more in the riverbed

Benefits of pile foundation

• Pile foundation is suitable for a wide range of soil types, including soft and unstable soils, as it can reach stable soil layers deep beneath the surface.
• It can support large loads and is capable of withstanding lateral forces, such as wind and seismic activity.
• Pile foundation can be designed to resist buoyancy forces, which can be a problem in areas with high water tables.

Disadvantages of pile foundation:

• Pile foundation can be more expensive than other types of foundation due to the amount of material and labor required.
• It can be difficult to install piles in certain soil types, such as rock or hard clay.
• Pile foundation can be noisy and disruptive to nearby buildings and residents during installation.

Applications of pile foundation:

• Pile foundation is commonly used in the construction of high-rise buildings, bridges, and other structures with heavy loads or poor soil conditions.
• It is also suitable for structures located in areas with seismic activity or high wind loads.

Examples of construction projects that use pile foundations:

• The Burj Khalifa, the tallest building in the world, uses a pile foundation system to support its massive weight.
• The Golden Gate Bridge in San Francisco uses pile foundation to support its towering pillars and massive weight.
• Pile foundation is also commonly used in the construction of bridges, offshore structures, and other large-scale infrastructure projects.

6. Drilled Shafts or Caisson Foundation

Drilled shaft foundation, also known as drilled pier or caisson foundation, is a type of deep foundation that is used to support heavy loads or when the soil conditions at the surface are not suitable for shallow foundations. It consists of deep, cylindrical holes drilled into the ground and filled with reinforced concrete or steel.

Drilled shafts or caisson foundation is a watertight retaining structure used as bridge pier, construction of dams, etc. It is generally used in structures that require a foundation beneath a river or similar water bodies. The reason for choosing the caisson is that it can be floated to the desired location and then sunk into place.

It has an action similar to pile foundations discussed above but is high-capacity cast-in-situ foundations. It resists loads from the structure through shaft resistance, toe resistance, and/or a combination of both. The construction of drilled shafts or caissons is done using an auger.

Caisson foundation is a ready-made hollow cylinder depressed into the soil up to the desired level and then filled with concrete, which ultimately converts to a foundation. It is mostly used as bridge piers. Caissons are sensitive to construction procedures and require construction expertise.

Drilled shafts can transfer column loads larger than pile foundations. It is used where the depth of hard strata below ground level is located within 10m to 100m (25 feet to 300 feet).

Drilled shafts or caisson foundation is not suitable when deep deposits of soft clays and loose, water-bearing granular soils exist. It is not suitable for soils where caving formations are difficult to stabilize, soils made up of boulders, and an artesian aquifer exists.

There are several types of caisson foundations

1. Box Caissons
2. Floating Caissons
3. Pneumatic Caissons
4. Open Caissons
5. Sheeted Caissons
6. Excavated Caissons

Caisson foundations are economic when:

1. The pile cap requirement is to be minimized
2. Noise and vibration needed to be reduced
3. It has to be placed beneath water bodies
4. Highly lateral and axial loading capacity is required

Benefits of drilled shaft foundations:

• Drilled shaft foundations are suitable for a wide range of soil types, including soft and unstable soils.
• They can support large loads and are capable of withstanding lateral forces, such as wind and seismic activity.
• Drilled shaft foundations can be designed to resist buoyancy forces, which can be a problem in areas with high water tables.
• They can be more cost-effective than other deep foundation methods, such as pile foundations, for certain types of soil conditions.

Disadvantages of drilled shaft foundations:

• Drilled shaft foundations can be more difficult to construct than other types of deep foundations, requiring specialized equipment and expertise.
• They can be noisy and disruptive to nearby buildings and residents during construction.
• The diameter of the drilled shafts may be limited in certain soil types, which can impact the load-bearing capacity of the foundation.

Applications of drilled shaft foundations:

• Drilled shaft foundations are commonly used in the construction of high-rise buildings, bridges, and other structures with heavy loads or poor soil conditions.
• They are also suitable for structures located in areas with seismic activity or high wind loads.
• Drilled shaft foundations can be used in various construction projects, including transportation infrastructure, commercial buildings, and power plants.

Examples of construction projects that use drilled shaft foundations:

• The Bayonne Bridge in New York and New Jersey uses drilled shaft foundations to support its massive weight and withstand strong winds.
• The One World Trade Center in New York City uses drilled shaft foundations to support its massive weight and height.
• Drilled shaft foundations are also commonly used in the construction of bridges, wind turbines, and other large-scale infrastructure projects.

7. Pier Foundation

A Pier foundation is an underground structure that transmits a more heavy load, which cannot be carried by shallow foundations. It is usually shallower than a pile foundation. The pier foundation is generally used in multi-story structures.

A Pier foundation is a type of shallow foundation that consists of cylindrical concrete columns, or piers, which are used to support a building or structure. The piers are spaced at regular intervals and can be connected by grade beams to distribute the load of the building evenly.

Pier is a cylindrical structural member that transfers heavy load from the superstructure to the soil by end bearing. Unlike piles, it can only transfer load by bearing and by not skin friction.

Pier Foundations are used economically when:

• Sound rock strata lie under a decomposed rock layer at the top
• The topsoil is stiff clay that resists driving the bearing pile
• When a heavy load is to be transferred to the soil

Pier Foundation has many advantages:

• It has a broad scope of assortment with regards to structure. There are different materials we can here to build a stylish view, and it stays within our spending limit.
• It sets aside cash and time as it doesn’t require the broad removal of a ton of cement. 
• Bearing limits can increment by under-reaming the base.

Along with the advantages, it has a few disadvantages as well:

• If one post or dock is harmed, it can prompt critical harm to the general establishment.
• It can be vitality wasteful if not protected appropriately. 
• Floors must be intensely, vigorously protected, and shielded from critters.

Benefits of pier foundations:

• Pier foundation is suitable for buildings with light to moderate loads, and can be more cost-effective than other types of foundation for certain types of soil conditions.
• It is less vulnerable to the effects of shrinkage and swelling of the soil, which can cause cracks in the building.
• Pier foundations can be designed to incorporate insulation and other features that can improve the energy efficiency of the building.

Disadvantages of pier foundations:

• Pier foundations may not be suitable for buildings with heavy loads or poor soil conditions, as it may not be able to distribute the load evenly.
• It may require more excavation and preparation work than other types of foundation.
• Pier foundations may not be suitable for sites with high water tables, as the water can undermine the foundation and cause instability.

Applications of pier foundations:

• Pier foundation is commonly used in the construction of small to medium-sized buildings, such as houses and small commercial buildings.
• It is also suitable for buildings with irregular or unusual shapes, as it can be designed to fit the specific requirements of the building.

Examples of construction projects that use pier foundations:

• The Eames House in Los Angeles, California, designed by Charles and Ray Eames, uses a pier foundation to support its iconic design and structure.
• The Glass House in New Canaan, Connecticut, designed by Philip Johnson, uses a pier foundation to elevate the building off the ground and provide a minimalistic appearance.
• Pier foundation is also commonly used to construct beach houses and other structures on sandy or unstable soil.

Special Foundations

8. Bridge Abutments

Bridge abutments are the structures that support the ends of a bridge and transfer the load from the bridge to the ground. They are typically constructed from concrete, masonry, or steel, and are designed to withstand the forces exerted by the bridge and the environment.

Benefits of bridge abutments:

• Bridge abutments provide a stable and secure foundation for bridges, ensuring that they are able to withstand the forces of wind, water, and traffic.
• They can be designed to incorporate aesthetic features that complement the design of the bridge and the surrounding landscape.
• Bridge abutments can be designed to resist the effects of erosion and scouring, which can undermine the foundation of the bridge.

Disadvantages of bridge abutments:

• Bridge abutments can be expensive to construct, especially in areas with difficult soil conditions or limited access.
• They may require regular maintenance and repair to ensure that they remain stable and secure over time.
• Bridge abutments can have a significant impact on the surrounding environment and may require environmental permits and approvals.

Applications of bridge abutments:

• Bridge abutments are used in the construction of a wide range of bridges, including highway bridges, pedestrian bridges, and railway bridges.
• They are essential components of most bridge designs and are required to ensure the safety and stability of the bridge.

Examples of construction projects that use bridge abutments:

• The Golden Gate Bridge in San Francisco, California, features massive concrete abutments that anchor the ends of the suspension cables and support the weight of the bridge.
• The Brooklyn Bridge in New York City, New York, features masonry abutments that support the massive stone towers and the weight of the bridge deck.
• The Tacoma Narrows Bridge in Tacoma, Washington, features steel abutments that support the suspension cables and the weight of the bridge deck.

In summary, bridge abutments are essential components of most bridge designs and play a critical role in ensuring the safety, stability, and longevity of the bridge.

While they can be expensive to construct and maintain, they provide a stable and secure foundation for bridges. They can be designed to incorporate aesthetic features that complement the design of the bridge and the surrounding landscape.

9. Retaining Walls

Retaining walls are structures that are used to hold back soil and prevent it from sliding or collapsing. They are typically constructed from concrete, masonry, or stone and are used in a variety of applications, including building foundations, landscaping, and erosion control.

Benefits of retaining walls:

• Retaining walls provide a stable and secure foundation for buildings, ensuring that they remain stable and secure even in areas with unstable soil conditions.
• They can be used to create level areas on sloping terrain, making it possible to build structures or plant gardens in otherwise unusable areas.
• Retaining walls can be designed to incorporate aesthetic features that complement the surrounding landscape and enhance the appearance of the property.

Disadvantages of retaining walls:

• Retaining walls can be expensive to construct, especially in areas with difficult soil conditions or limited access.
• They may require regular maintenance and repair to remain stable and secure over time.
• Retaining walls can have a significant impact on the surrounding environment and may require environmental permits and approvals.

Applications of retaining walls:

• Retaining walls are commonly used in the construction of building foundations, especially in areas with unstable soil conditions or steep slopes.
• They are also used in landscaping to create level areas on sloping terrain, to prevent erosion and to create terraced gardens.
• Retaining walls can be used in transportation infrastructure, such as highways and railways, to prevent soil from sliding onto the road or tracks.

Examples of construction projects that use retaining walls:

• The Burj Khalifa in Dubai, United Arab Emirates, uses retaining walls to support the massive weight of the building and prevent soil from sliding or collapsing.
• The terraced rice paddies in Bali, Indonesia, use retaining walls to create level areas on steep slopes and prevent erosion.
• The Interstate 5 freeway in Los Angeles, California, uses retaining walls to prevent soil from sliding onto the road and to protect nearby buildings from damage.

Retaining walls are a versatile and effective solution for holding back soil and preventing it from sliding or collapsing.

While they can be expensive to construct and maintain, they provide a stable and secure foundation for buildings and can be designed to incorporate aesthetic features that complement the surrounding landscape.

They are used in a wide range of applications, including building foundations, landscaping, and erosion control.

10. Tunnels

Tunnels are underground structures that are used to transport people, vehicles, or goods from one location to another. They are typically constructed from concrete, steel, or other durable materials and are used in a variety of applications, including transportation, water supply, and mining.

Benefits of tunnels:

• Tunnels can provide a faster and more efficient mode of transportation than surface-level routes, as they avoid traffic congestion and other obstacles.
• They can also be used to transport goods and supplies that would be difficult or impossible to transport overland.
• Tunnels can be designed to minimize the environmental impact of transportation, as they reduce noise and air pollution.

Disadvantages of tunnels:

• Tunnels can be expensive to construct, especially in areas with difficult geology or limited access.
• They may require regular maintenance and repair to ensure that they remain stable and secure over time.
• Tunnels can pose safety risks to workers and passengers, especially in the event of a fire or other emergency.

Applications of tunnels:

• Tunnels are commonly used in transportation infrastructure, such as highways, railways, and subways.
• They are also used in water supply infrastructure to transport water from one location to another.
• Tunnels are used in mining operations to transport ore and other materials from underground.

Examples of construction projects that use tunnels:

• The Channel Tunnel, also known as the Eurotunnel, connects England and France through an underwater tunnel that spans 31 miles (50 km).
• The Gotthard Base Tunnel in Switzerland is the longest railway tunnel in the world, spanning 35 miles (57 km) beneath the Swiss Alps.
• The New York City Subway system includes dozens of tunnels that transport millions of passengers every day.

Tunnels are a versatile and effective solution for transporting people, goods, and supplies from one location to another.

While they can be expensive to construct and maintain, they provide a faster and more efficient mode of transportation than surface-level routes.

They can be designed to minimize the environmental impact of transportation. They are used in a wide range of applications, including transportation, water supply, and mining.

References:

1. “Strip Foundation – Designing Buildings Wiki.” Designing Buildings Wiki, n.d. https://www.designingbuildings.co.uk/wiki/Strip_foundation.
2. “Raft Foundations – Designing Buildings Wiki.” Designing Buildings Wiki, n.d. https://www.designingbuildings.co.uk/wiki/Raft_foundations.
3. “Pile Foundation – Designing Buildings Wiki.” Designing Buildings Wiki, n.d. https://www.designingbuildings.co.uk/wiki/Pile_foundation.
4. “Drilled Shafts – FHWA Geotechnical Engineering Circular No. 10 (FHWA-NHI-16-009).” FHWA Geotechnical Engineering Circular No. 10 (FHWA-NHI-16-009) – 8. Drilled Shafts | FHWA, n.d. https://www.fhwa.dot.gov/engineering/geotech/pubs/16009/08.cfm.
5. “Pier Foundations – Designing Buildings Wiki.” Designing Buildings Wiki, n.d. https://www.designingbuildings.co.uk/wiki/Pier_foundations.
6. “Retaining Walls – Designing Buildings Wiki.” Designing Buildings Wiki, n.d. https://www.designingbuildings.co.uk/wiki/Retaining_walls.
7. “Tunnel Construction: How Tunnels Are Built.” History. A&E Television Networks, LLC, May 22, 2019. https://www.history.com/news/tunnel-construction-how-tunnels-are-built.
8. “Eurotunnel – History and Construction of the Channel Tunnel.” Engineering Timelines. Engineering Timelines, n.d. https://www.engineering-timelines.com/scripts/engineeringItem.asp?id=1166.
9. “Gotthard Base Tunnel – Railway Technology.” Railway Technology. Kable, n.d. https://www.railway-technology.com/projects/gotthard-base-tunnel/.
10. “New York City Subway.” Wikipedia. Wikimedia Foundation, April 22, 2023. https://en.wikipedia.org/wiki/New_York_City_Subway.

Frequently Asked Questions on Types of Foundations