There’s no doubt that the foundations of any building project are among the most important elements when it comes to ensuring the longevity and stability of the resulting structure. They provide the solid base that’s required to protect the building from the rigours of the elements and the loads placed on them. Groundworks specialists will recommend different types of foundations, depending on the soil type, the kind of building they are there to support and the materials that will be used in its construction.
Here, we give a brief overview of some of the different types.
Shallow or Deep Foundations?
The first distinction is between shallow and deep foundations. Shallow foundations are most commonly required where the load of the building is relatively low, compared to the ground’s capacity to bear it. Deeper foundations are needed where the building is more extensive – in other words, will provide greater loads for the soil below to bear; and/ or where the quality of the surface soil is not adequate to carry the load that will be imposed upon it by the structure.
Other considerations might include the presence of water on the site and drainage; the space available for the building; the accessibility of the site and general conditions, such as the vibration the structure will be subjected to.
Types of Shallow Foundations
Again, in broad terms, there are three main types of foundations. These include individual footings, where the building load is supported by columns, each with its own footing. Then there are raft foundations, which are often used when basement construction is included in the building’s plans. These spread the building load over the entire area of the structure. Finally, strip footings consist of long trenches which carry the entire weight of individual walls, rather than single columns.
Types of Deep Foundations
Deep foundations use pilings, structural piles which are driven or set in pre-dug holes deep into the soil. Piles are long, slim column-shaped units, usually made from steel or reinforced concrete. These offer a very firm foundation for buildings when correctly spaced by distributing the weight of the building evenly across the area they span. Generally, these are classified as either end-bearing piles or friction piles. In the former case, most of the friction is concentrated at the base of the pile; whereas in friction piles, it’s spread along the sides.
Then, piles can either be driven or bored into the ground, displacing the soil around them or filling cavities where the soil has been removed prior to their siting.
If access to the foundation area is restricted for any reason, for example when an existing structure needs underpinning because it has settled, micropiles (or mini piles) can be inserted.
If you need advice on the right kind of foundations for your project, or expertise in their construction, Tricourt Piling and Foundations Ltd can assist. We offer our services across Dorset, Hampshire and the South West and are specialists in groundworks of all types, including pilings, reinforced concrete, steel fixing and formwork, retaining walls and more.