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Spread Footings - Types, Applications and Advantages

Spread foundations are the solid foundation system which has been used for supporting the columns of the building along with a good load-bearing capacity. The spread footing helps to prevent soil failure by distributing the heavy loads of the building structures. The tall and heavy structures have been also supported by the unique properties of spread footing. The spread footing has the ability to stabilise the building by balancing the upward soil pressure along with the downward load of the building structure.

Advantages of using Spread Footing

There are several advantages of using spread footing in the construction process which includes:

• Spread footing can be available in different shapes such as squares, rectangular, or rounds on the basis of different applications.
• This type of footing can be constructed easily within a short period of time.
• The construction process of spread footing is cost-effective in terms of labour.
• There is less trained personnel is required for constructing the spread footings.
• In the case of the less load-bearing capacity of the soil, spread footing helps to distribute the building load over a large area.
• The materials that are used for constructing spread footing are readily available.
• There is less chance of having a differential settlement while using spread footing.
• There is a lower rate of failure of spread footing as compared to other types of footing.
• For the construction of residential houses, spread footing has been commonly used.

Different applications of Spread Footing

• The price of spread footing is reasonable and appropriate for a wide range of constructions such as commercial buildings, factories or residences.
• The strip footings have been used to provide support to the load-bearing walls in multi-storey buildings or warehouses.
• The raft footing has been used for major construction structures including high-rise buildings or bridges as this type of spread footing is used to spread the load steadily and evenly.

How to construct a Spread Footing

The construction of the spread footing has been done in several stages which include:

• At the initial stage, the trench should be dug, reinforcement rods have been added, concrete has been poured, and excavated dirt used to backfill the pit.
• In the case of shallow excavations, the support of the wall is not necessary. But in case of deeper excavation, wall support or slopping is necessary.
• The supported wall is also needed for excavations that are close to the property line. In this context, the vertical timber boards have been used for excavations under 10 feet deep. In the case of deeper excavations, more substantial support systems are needed.
• The vertical cuttings have been supported by soldier pile systems or steel sheet piles. These pile systems have been used in the pace of timber sheeting for deeper excavations that are more than 12 to 15 feet.
• In unstable soil conditions including tiebacks, dry sand, or inclined braces, the steel sheet piles have been utilised in place of soldier piles.

Different types of Spread Footing

There are different types of spread footing which have been used on the basis of the load-bearing capacity of the soil. The different types of spread footings include:

Strip Footing

This type of spread footing is a long and narrow type of footing which helps to support the line of the column of the walls. The continuous line strip footing has been used in the load-bearing walls. In this case, the base of this type of footing helps to cover a wide range of areas of the ground as well as helps to transfer the load of the building structure to a large area.

Pad Footing

These types of spread footing are square or rectangular in shape, so, this pad footing often is also called rectangular or square footing. In this case, the load of the construction structure has been distributed vertically over the large area. In small construction projects or residential projects, pad footing can be used.

Circular Footing

This type of spread footing is circular in shape which helps to support the individual columns or loads. This circular footing is generally used in cases of circular cross-section shapes are used. This type of spread footing helps to provide a better appearance.

Stepped Footing

This spread footing is also known as the sloped footing. This type of footing has been used in the case of the soil bearing capacity has increased at the deeper level. The series of steeped footing or tiers helps to allow the wider base of the footing on the basis of the greater depth.

Combined Footing

In the case of two or more columns that have been closed to each other and overlapping with each other, the combined spread footing has been used. This type of spread footing has been constructed for supporting multiple columns which helps to transfer the building’s load over a large area.

Strap Footing

In the case of two or more columns connected with the help of a concrete beam, the footing is called strap footing. This strap footing is also known as connecting footing which is used in case the isolated footing or columns are close to each other and the load has been distributed uniformly.