Concrete home foundations are designed and constructed to coincide with the climate, type of soil, and type of home. All of these factors dictate the shape, size, depth, reinforcements, etc of the foundation details.
Due to high water table at places near sea level, homes are built with very shallow foundations similar to details 13 and 14. Concrete block foundations are very common at these types of applications. Also common in these areas are absence of waterproof foundation because high water table is not a good environment for basements.From cost stand point, detail 13 works better if labor is relatively inexpensive. In this detail, there will be 3 different concrete pours required. The first pour being the footings followed by the foundation walls before the floor slabs.
An alternate to detail 13 is to use block wall in lieu of concrete foundation wall. After the footing is poured, install 8 inch cinder block reinforced vertically with #4 at 32 inches on center, grout it solid, backfill the interior and then pour the slab.
In areas where detail 13 works detail 14 will work too. If labor cost is high, detail 14 will be a better choice because it will cut the cost of labor in detail 13 by more than 50 percent.
Detail 14 is also known as monolithic slab because the footings, foundations, and slabs are poured simultaneously. This option will require more concrete, as much as 5 cubic yards +/- of concrete extra.
In the USA, the cost of 5 cubic yards of concrete is pocket change compared to extra labor and cost of forming material for foundation walls.
In other parts of the world forming home foundations or building a block wall is a better option because of low labor rate. Either way both details work for shallow foundations.
Whether constructing foundation footing for a house, garage foundation, or shed foundation, details 13 and 14 can apply and can be used.
Word of Caution
Prior to finalizing any type of footings & foundations to be used at your project, examine the existing structures in the area. Any visible severe slabs cracking or settlements and/or foundation cracking, wall or ceiling cracking are all signs foundation problems.
Talk to local building officials, local contractors, local building designers, etc regarding local building or construction issues that you may not aware of. These will help you make informed decision about the localities of your project so you can better prepare for what's ahead.
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