Where's a concrete footing located?
Concrete footing are the point at which both live loads and dead loads are released into the compacted soil or bedrock beneath the surface.
A footing is required for the following elements:
As a rule of thumb, the footing width should be twice the thickness of the foundation wall. If un-reinforced, the projection beyond the foundation should not exceeding the thickness of the concrete strip footing.
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Factors that govern the size of a footing
Footings are design to accommodate design loads and withstand other factors such as:
High water table
The local building code
and construction blueprint may resolves the design issue for residential requirement of a footings, however for more complex design calculation the service of license Engineer may be necessary.
If your construction drawings were not specifically prepare but purchased online and courier chances are the foundation does not conform to local building code
For quick reference view
table for minimum footing size
The most common of footings are the spread footing which is also referred to as strip footing.
Strip footing may include cross directional re-bars located near the base of the footing which adds tensile properties to the footing thus preventing it from deflecting.
Also a key, and dowels, provide means of a vertical connection from the footing to the foundation wall. View diagram
Although re-bars may not be used in a typical residential home, but light commercial building carrier more loads and as a result require reinforcement.
This type of footing is used in conjunction with spread footing to on slope site.
The reason for stepping the footing on a slope to a lower elevation is to ensure that the footing maintains its required depth below the frost line thus eliminating risk of settlement due to the freeze - thaw cycle.
Slab-on-grade is suitable for warmer climate where freezing isn't an issue of concern.
This type of foundation is the least expensive to construct for this reason,it's not design to support multiple floors. As a result it consist to simple components a slab and perimeter grade beam.
The slab of this foundation is reinforced with welded wire mesh. This WWM reduces the effects of the cracking as the concrete slab dehydrates over a period of time.
The beam may include re-bars to ensure load on crack due to point load occur.
This type of concrete footing isn't continuous and supports point load as in the case of a column.
Column footing also contain cross-directional re-bars near the base of the pad footing.
Interested in learning more about the detailing process of a basement foundation
to gain information on how it correctly detail a foundation plan.
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