A footing is the base that sits on the earth/ rock and usually supports the loads above and on it. A slab is between footings, sometimes sits on footings or part of footings. Sometimes slabs are between walls or outside walls. The do not always take load but can be designed that way.
The footings are the wide pieces of concrete that are placed deep into the ground to prevent movement. The foundation walls are then placed on top of the footings, and resting in between the two is the concrete slab which makes up the basement floor.
What Is a Footing? The bottom part of a foundation is called the footing. Footings in construction are critical, as the footing distributes the weight of the building evenly across the entire structure so that it doesn't sink into the ground.
A slab is a single concrete base. Footings and other load-bearing elements are added to the slab. The unit works together to anchor the house, and the exterior walls and interior load-barring walls rest on the slab. There is limited separation between the home and the slab.
Monolithic slabs combine the foundation footings and slab into one piece, allowing them to both be poured at the same time and cut back your time and monetary investment.
The foundation can be both shallow or deep, but the footing is typically only used in shallow instances. The footing will transmit the load directly to the soil and the foundation passes it to the ground. In short, all footings are foundations but not all foundations are footings.
Some houses don't have a basement or crawl space under them but are simply built on a concrete slab—perhaps because the house sits on bedrock or a high water table. The concrete is poured onto the ground all at one time.
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).
No Space for Storage or Utility Lines
Another significant downside to owning a home on a concrete slab is that you'll be missing out on the functional space that a full basement (and even a crawl space) can provide.
Depth of Footings
Footings should extend to a minimum depth of 12 inches below previously undisturbed soil. Footings must also extend at least 12 inches below the frost line (the depth to which the ground freezes in winter) or be frost-protected.
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.
Could you pour a concrete slab without footers? Technically, yes. But, it may not have the support it needs.
Cost-Effective: Because pier and beam foundations don't require as much concrete, they tend to be more cost-effective than slab foundations.
Construction Process
The slab is poured directly onto a prepared gravel or sand base without a separate footing. The slab edges may be thickened slightly, but they essentially sit on the ground surface.
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).
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.
Smaller sheds in areas without frost issues can often sit on a thickened-edge slab without full footings, while larger sheds or those in frost-prone regions benefit from the added stability of footings. Understanding your soil conditions and the intended use of the shed will also help you make the right choice.
It's better not to pour concrete directly onto the dirt. Instead, use a layer of gravel underneath your concrete slab. Because concrete is porous, it absorbs water. If you place concrete directly onto dirt, water will collect under the concrete and slowly erode the bottom of the pad.
Standard concrete floor slab thickness in residential construction is 4 inches. Five to six inches is recommended if the concrete will receive occasional heavy loads, such as motor homes or garbage trucks. To prepare the base, cut the ground level to the proper depth to allow for the slab thickness.
The best thing you can do is have these gaps caulked, either professionally or done yourself as a DIY project, although doing it yourself may not result in the aesthetic you're going for. A-1 Concrete Leveling offers professional concrete caulking services in addition to other concrete repair options.
A floating concrete slab is considered a footing since it distributes the weight of the structure to the soil, but not all concrete slabs are considered footings. For example, a T-shaped slab includes separate footings below the slab that support the concrete above and push the load further down into the ground.
Footings pouring one day to setting forms on walls is always under your discretion, 48-72 hours is plenty of time for the footings to set/ dry… But just make sure you have everything else ready for the slab after walls (including entry / exit points on the walls themselves).
Floating slabs are a form of foundation that provides an economical solution compared to traditional slab foundations. Floating slabs do not require excessive excavation but are constructed to "float" on the ground without direct supports like beams, footings or thickened edges.