The most common types of footing in residential construction are Isolated and Continuous
The most common type of footing is the shallow footing, which is typically used for small structures such as sheds or decks. Deep footings are used for taller structures such as buildings or bridges, and pile footings are used to support very heavy loads.
You can look up the recommended footing size, based on the size and type of house and the bearing capacity of the soil. As you can see, heavy houses on weak soil need footings 2 feet wide or more. But the lightest buildings on the strongest soil require footings as narrow as 7 or 8 inches.
Individual footings are the most common type of footing. They are usually used for small structures such as sheds or porches. Individual footings are also used for all four walls of a building if the soil is very soft or there is a high water table.
In most cases, a house should have a minimum footing of 12 inches wide by 12 inches deep, with foundations that are 8 to 10 inches thick. This should be enough to support house weight and resist lateral soil and water pressure.
For every 2 feet of adjustment to the width of the house, add or subtract 2 inches of footing width and 1 inch of footing thickness (but not less than 6 inches thick).
Most of the time we take footings for granted, and usually we can: For typical soils, a common 16- or 20-inch-wide footing can more than handle the relatively light weight of an ordinary house.
Reinforced Cement Concrete (RCC) increases footing strength and reduces the structural load on the foundation. RCC Footings spread the building load to reduce pressure on the foundation.
Precast cement blocks are probably the cheapest and easiest footings to install. Each block is buried right beneath the ground's surface.
C25 standardised mix concrete or ST2 Concrete is widely versatile and used in numerous commercial and domestic projects. It is commonly used for footings and foundations, including mass concrete fill, trench fill and reinforced fill, as well as general groundworks.
A minimum of 12”inches deep for all footings and the width will be determined by the amount of stories, 12” inches for a single story, 15” inches for a two story and 23” inches for a three story. This is based on a soil bearing capacity of 1500(psf).
Poured concrete is the strongest type of foundation for a house. Concrete is incredibly strong and durable, and it can be poured into any shape. This makes it ideal for supporting the weight of a house. Block foundations are also very strong, but they are not as flexible as poured concrete.
To determine the size of the footing, a simple formula is used: Structural Load (lbs) / Soil Capacity (psf) = Footing Surface Area Required (sq. ft.)
A concrete pad footing is the simplest and cost-effective footing used for the vertical support and the transfer of building loads to the ground. These footings are “isolated” i.e. there is no connection between them. They are also reinforced.
C25 is often used as a foundation concrete mix when pouring foundations (footings). It is also the ideal concrete for domestic slab foundations for house and bungalow floors.
Bored Piles
Bored pile foundations are the most common type of deep foundation built by boring holes in the soil before placing a pre-constructed concrete pile into them.
The footing depth, on the other hand, is typically determined by the soil type and the extent to which you must dig before striking undisturbed soil. Still, we recommend that the depth of the footing extends to a minimum of 12 inches after you've hit undisturbed soil.
Even the best contractors occasionally have to build on a sloppy footing. Ian Geisler, a noted ICF expert who has worked on hundreds of projects across the continent, says that realistically a perfect footing is anything within ¼” of level. “If it's within ½”, then it's workable,” he writes.
Use compaction whenever the soil is disturbed during construction or when it's used for fill. Compact disturbed soil beneath footings, slabs, basement floors, patios, garage floors, driveways, concrete steps and sidewalks. If a sand, gravel, or crushed stone base is used beneath a slab, compact it too.
The projection of the footing on either side of the wall is supposed to be no greater than the depth of the footing. So, for example, a 32-inch-wide footing under an 8-inch wall would need to be at least 12 inches thick.
Footings are structural supports that are used in addition to a foundation. They help transfer the load's weight from the foundation into the soil. Footers are typically in direct contact with the ground, while the foundation is in contact with the footing.
Soil compaction is often necessary to create a stable base for footings. This process increases soil density and load-bearing capacity. In some cases, engineers may recommend using gravel or crushed stone to improve drainage and stability beneath the footing.
The most common types of footing in residential construction are Isolated and Continuous spread footings. They are both part of a shallow foundation construction hence why they are used in residential construction. In addition, the other five footing types are Raft, Strap, Strip, Pile, and Combined footings.
Gravel provides drainage, stabilizes the soil, prevents erosion, and helps distribute weight more evenly. Without it, you risk the potential damages listed above. If you're planning a concrete project, don't skip the gravel layer—it's a foundation that ensures your concrete work stands the test of time.
Simple Gravel and Concrete Footing Design
The minimum footing thickness should not be less than the distance the footing extends outward from the edge of the foundation wall, or 6 inches, whichever is greater.