Buildings and homes require foundations to give them support, and are generally laid under the ground before construction takes place.
Foundations need to be built to have the right capacity to bear the load being built on them and be designed to survive the climate and conditions they will be enduring. Residential building foundations are generally shallow, whereas skyscrapers and high rise buildings have deep foundations to take the extra weight and pressure more successfully.
The choice of foundation for your home should be determined by the climate and what works best for the soil on your property, as well as your budget and time constraints.
Deep foundations transfer the weight of the structure from the weaker layer of topsoil (that shallow foundations are dug into) into the sturdier subsoil. One of the derivatives of a deep foundation is a monopole foundation, where a single structure is embedded in the ground to provide the support.
A strip foundation is the simplest and used on most small structures, in areas where ground water is not a problem. Pad foundations have pillars that rise from the foundation to the slab to provide the support and allow you to elevate a structure and make more practical space underneath it, like for underground parking. Raft foundations work well for low buildings in wet soil or areas where the soil is loose.
Spread footing building foundations consist of sheets of concrete that are placed under the frost line to shift the weight into the ground. Slab-on-grade foundations have a concrete pad that is on top of the ground, a couple of inches thick. They are thicker at the edges and used in areas where ground freezing does not take place.
T-shape foundations are suitable for use in areas that experience ground freezing. In this structure the footing is broader than the wall, and the concrete slab is laid after the walls.
In areas where the soil has a lot of clay, a crawlspace foundation is popular. It leaves a space between the first floor of the house and the ground. Basement foundations are popular in areas where there is ground frost, and the foundations need to be elevated above the surface of the ground and provide more headspace than a crawlspace foundation. Slab building foundations are used in areas where the water table is high and there is no accessible space between the concrete and the grade.