What is footing? Different type of footings.

Footings are the structures that provide a foundation and support for the walls of a building. They distribute the weight of the building evenly onto the soil, and prevent the building from sinking into the ground or shifting. Footings are typically made of concrete, and their design and construction must meet certain specifications and regulations to ensure the stability and safety of the building.

Different type of footings

There are several types of footings used in construction, including:

1. Strip Footings: These are narrow, rectangular footings that support walls.
2. Isolated Footings: These are separate footings for individual columns.
3. Combined Footings: These are footings that support more than one column, and are used when the columns are too close together for individual footings.
4. Wall Footings: These are footings that support load-bearing walls.
5. Raft Footings: Also known as mat footings, these are large, continuous footings that support an entire building.
6. Pile Footings: These are footings that transfer the weight of the building to deep layers of soil or rock, and are used in areas with shallow soil or poor soil conditions.
7. Strap Footings: These are footings that connect two or more isolated footings to distribute loads evenly.

Each type of footing is used in different circumstances, and the type used will depend on factors such as soil conditions, the size and weight of the building, and local building codes.

1. Strip Footings

Strip footings are narrow, rectangular footings that support the walls of a building. They are used in situations where the soil can bear the weight of the building, but additional support is needed to distribute the weight evenly.

The procedure for constructing strip footings typically involves the following steps:

1. Excavation: The soil is excavated to a depth that allows for the strip footing to be set at the required level.
2. Reinforcement: Steel reinforcement bars, known as rebar, are placed in the excavation to reinforce the concrete.
3. Concrete Pour: Concrete is poured into the excavation and leveled off. It’s important to ensure the concrete is poured evenly, with no voids or air pockets, to avoid weak spots in the footing.
4. Curing: The concrete is allowed to cure for several days, during which time it will harden and gain strength.
5. Wall Construction: Once the footings have cured, the walls of the building can be constructed on top of them.

Strip footings are used in residential and commercial construction, and are particularly useful in areas where the soil has good bearing capacity. They are relatively inexpensive and easy to construct, and can be designed to accommodate a wide range of load conditions. However, they are not appropriate for use in areas with soil that is unstable or has poor bearing capacity, as the strip footing may not provide enough support to prevent the building from settling or shifting. In these cases, a more robust type of footing, such as a pile footing, may be needed.

2. Isolated Footings

Isolated footings are separate footings that support individual columns in a building. They are typically used in situations where the columns are widely spaced, and the soil can bear the weight of the building.

The procedure for constructing isolated footings typically involves the following steps:

1. Excavation: The soil is excavated to a depth that allows for the isolated footing to be set at the required level. The excavation is typically wider than the footing to allow for the placement of rebar and concrete.
2. Reinforcement: Steel reinforcement bars, known as rebar, are placed in the excavation to reinforce the concrete.
3. Concrete Pour: Concrete is poured into the excavation and leveled off. It’s important to ensure the concrete is poured evenly, with no voids or air pockets, to avoid weak spots in the footing.
4. Curing: The concrete is allowed to cure for several days, during which time it will harden and gain strength.
5. Column Construction: Once the footings have cured, the columns can be constructed on top of them.

Isolated footings are a versatile and effective solution for supporting columns in a building, and are commonly used in both residential and commercial construction. They are relatively simple to construct, and can be designed to accommodate a wide range of load conditions. However, they are not appropriate for use in areas with soil that is unstable or has poor bearing capacity, as the isolated footing may not provide enough support to prevent the building from settling or shifting. In these cases, a more robust type of footing, such as a pile footing, may be needed.

3. Combined Footings

Combined footings are footings that support more than one column in a building, and are used when the columns are too close together for individual footings. They are designed to distribute the weight of the building evenly, and prevent the columns from settling or shifting.

The procedure for constructing combined footings typically involves the following steps:

1. Excavation: The soil is excavated to a depth that allows for the combined footing to be set at the required level. The excavation is typically wider than the footing to allow for the placement of rebar and concrete.
2. Reinforcement: Steel reinforcement bars, known as rebar, are placed in the excavation to reinforce the concrete.
3. Concrete Pour: Concrete is poured into the excavation and leveled off. It’s important to ensure the concrete is poured evenly, with no voids or air pockets, to avoid weak spots in the footing.
4. Curing: The concrete is allowed to cure for several days, during which time it will harden and gain strength.
5. Column Construction: Once the footings have cured, the columns can be constructed on top of them.

Combined footings are a cost-effective solution for supporting multiple columns in a building, and are commonly used in both residential and commercial construction. They are relatively simple to construct, and can be designed to accommodate a wide range of load conditions. However, they are not appropriate for use in areas with soil that is unstable or has poor bearing capacity, as the combined footing may not provide enough support to prevent the building from settling or shifting. In these cases, a more robust type of footing, such as a pile footing, may be needed.

4. Wall Footings

Wall footings are footings that support the walls of a building and distribute the weight of the building evenly. They are typically used in situations where the soil cannot bear the weight of the building on its own, and additional support is needed to prevent the walls from settling or shifting.

The procedure for constructing wall footings typically involves the following steps:

1. Excavation: The soil is excavated to a depth that allows for the wall footing to be set at the required level. The excavation is typically wider than the footing to allow for the placement of rebar and concrete.
2. Reinforcement: Steel reinforcement bars, known as rebar, are placed in the excavation to reinforce the concrete.
3. Concrete Pour: Concrete is poured into the excavation and leveled off. It’s important to ensure the concrete is poured evenly, with no voids or air pockets, to avoid weak spots in the footing.
4. Curing: The concrete is allowed to cure for several days, during which time it will harden and gain strength.
5. Wall Construction: Once the footings have cured, the walls of the building can be constructed on top of them.

Wall footings are commonly used in residential and commercial construction, and are particularly useful in areas with soil that has poor bearing capacity. They are relatively inexpensive and easy to construct, and can be designed to accommodate a wide range of load conditions. However, they are not appropriate for use in areas with soil that is unstable, as the wall footing may not provide enough support to prevent the building from settling or shifting. In these cases, a more robust type of footing, such as a pile footing, may be needed.

5. Raft Footings

Raft footings, also known as mat footings, are a type of footing that is designed to support an entire building or a large portion of a building. They are typically used in areas where the soil has poor bearing capacity, and the weight of the building needs to be distributed evenly over a large area to prevent settling or shifting.

The procedure for constructing raft footings typically involves the following steps:

1. Excavation: The soil is excavated to a depth that allows for the raft footing to be set at the required level. The excavation is typically wider than the footing to allow for the placement of rebar and concrete.
2. Reinforcement: Steel reinforcement bars, known as rebar, are placed in the excavation to reinforce the concrete. The rebar is typically placed in a grid pattern, with additional reinforcement along the perimeter of the footing to ensure stability.
3. Concrete Pour: Concrete is poured into the excavation and leveled off. It’s important to ensure the concrete is poured evenly, with no voids or air pockets, to avoid weak spots in the footing.
4. Curing: The concrete is allowed to cure for several days, during which time it will harden and gain strength.
5. Building Construction: Once the raft footing has cured, the rest of the building can be constructed on top of it.

Raft footings are a robust and effective solution for supporting buildings in areas with soil that has poor bearing capacity. They provide a stable base for the building and can be designed to accommodate a wide range of load conditions. However, they are more expensive and complex to construct than other types of footings, and may require specialized equipment and expertise. Additionally, they are not appropriate for use in areas with soil that is unstable, as the raft footing may not provide enough support to prevent the building from settling or shifting. In these cases, a more robust type of footing, such as a pile footing, may be needed.

6. Pile Footings

Pile footings are footings that are driven or cast into the ground to provide support for a building or structure. They are typically used in areas where the soil has poor bearing capacity, or the building is located in a flood-prone area, and the weight of the building needs to be transferred to deeper, more stable soils or rock.

The procedure for constructing pile footings typically involves the following steps:

1. Site Investigation: A site investigation is performed to determine the soil type and conditions, as well as the location of any potential obstructions.
2. Pile Design: A pile design is created based on the site conditions and the load requirements of the building. The design will specify the type, size, and number of piles required.
3. Pile Installation: Piles are either driven into the ground using a pile driver, or cast in place using a drilled hole and concrete. The piles are typically driven or cast to a depth below the maximum depth of the soil or water table.
4. Pile Reinforcement: Reinforcement is added to the piles as needed, to increase their strength and stability.
5. Building Construction: Once the piles have been installed, the building can be constructed on top of them.

Pile footings are a robust and effective solution for supporting buildings in areas with soil that has poor bearing capacity, or where the building is located in a flood-prone area. They provide a stable base for the building and can be designed to accommodate a wide range of load conditions. However, they are more expensive and complex to construct than other types of footings, and may require specialized equipment and expertise. Additionally, pile footings can be subject to damage from natural forces such as earthquakes, so they need to be designed and constructed with these potential risks in mind.

7. Strap Footings

Strap footings are a type of footing used in building construction to support structures when two or more columns are close together and the load they carry cannot be effectively supported by a single footing. The footings are connected by a horizontal member, known as a strap, which transfers the load between the footings.

The procedure for constructing strap footings typically involves the following steps:

1. Excavation: The soil is excavated to a depth that allows for the footings to be set at the required level. The excavation is typically wider than the footings to allow for the placement of rebar and concrete.
2. Reinforcement: Steel reinforcement bars, known as rebar, are placed in the excavation to reinforce the concrete. The rebar is typically placed in a grid pattern, with additional reinforcement along the perimeter of the footings to ensure stability.
3. Concrete Pour: Concrete is poured into the excavation and leveled off. It’s important to ensure the concrete is poured evenly, with no voids or air pockets, to avoid weak spots in the footings.
4. Strap Placement: The strap is placed on top of the footings and secured in place. The strap may be made of concrete, steel, or another material, and its size and strength are determined by the load requirements of the building.
5. Curing: The concrete is allowed to cure for several days, during which time it will harden and gain strength.
6. Building Construction: Once the strap footings have cured, the rest of the building can be constructed on top of them.

Strap footings are useful when two or more columns are close together, as they provide a more efficient means of transferring the load from the columns to the ground. They also allow for greater flexibility in column placement and can be used to support structures with uneven loads. However, they are more complex to construct than other types of footings and may require additional materials and labor.