Building foundations fall into two main categories; shallow foundations and deep foundations. These categories simply refer to the depth at which the building’s piling foundations need to be driven to provide adequate support for the completed structure.
Shallow foundations are generally those that are wider than the overall depth and deep foundations have a smaller width when compared to the depth. But each category contains a number of different types of foundations.
Here we take a look at the different types of shallow foundations available:
Isolated Spread Footing
Also known as Pad or, simply, Spread footings, isolated footings are one of the most common shallow foundation types used to spread the weight of concentrated loads. Columns and pillars are the most common loads; these bare down on a relatively small surface area and can hold considerable weight above them so require stable foundations consisting of either reinforced or non-reinforced material. For non-reinforced material, the footing height has to be enlarged to provide the necessary spreading of the load.
Wall Footing
A wall footing does exactly what it says on the tin. A continuous slab strip that runs the length of a wall, generally two to three times the width of the wall in question, providing enough support and weight distribution for the load-bearing walls above. These types of supports link the foundation of a building to its vertical walls.
Combined footing
Similarly to Isolated Spread footings, these foundations support columns and pillars. Where they differ is that isolated footings can only be used when the columns are spaced well apart. When the columns are close together and their foundations overlap, a different technique (combined footings) is necessary. These can also be used if the bearing capacity of the soil is low.
The foundations themselves are usually rectangular, tee-shaped or trapezoidal. They work to distribute the loads evenly to coincide the centre of gravity of the footing area with the centre of gravity of the total load.
Cantilever or Strap Footing
Strap footings work in a similar fashion to combined footings, however, strap footings under the columns are built individually and connected together using a concrete beam known as a strap beam. This is used to help evenly distribute heavy or unusually placed loads. A cantilever footing is usually used in conjunction with columns located along a property line.
Raft or Mat Foundation
These are the best options for when all other shallow foundations or pile foundations are unsuitable. Raft foundations consist of a reinforced slab of concrete or T-beam slab placed over the entire surface of the structure. This slab acts as the building’s basement slab and supports the whole weight of the structure spreading the weight evenly.
Rhino Piling provides piling in Manchester and the surrounding areas for both domestic and commercial properties. Get in touch with the team today to find out more information.
