What kind of soil is your house foundation sitting on?
Posted by Craig Milam on Tue, Oct 27, 2009 @ 12:34 PM
According to the United States Department of Agriculture Travis County features a smorgasbord of soil types. Some of which are great for supporting foundations and others of which pose plenty of problems for construction.
What type of soil is your home or potential new home sitting on?
This blog article will examine Austin soil types using excerpts from the USDA's report on Soils in Travis County.
According to the report:
Foundations
Shrink-swell characteristics of the soil need to be considered in designing a
building foundation, particularly if piers are not used below the slab. Such clay soils
as those of the Houston Black, San Saba, and Ferris series are particularly poorly
suited to building sites. They swell when wet and shrink when dry. This shrinking
and swelling exerts such pressure that walls and foundations crack unless they are
specially reinforced, sidewalks and driveways crack, and streets and sidewalks
deteriorate more quickly.
In otherwords, beware of the type of soil your house is sitting on.
The report defines shrink-swell potenial as follows:
Shrink-swell potential is an indication of the volume change to be expected in the
soil material as the moisture content changes. Shrinking and swelling of soils causes
much damage to building foundations, roads, and other structures. A high shrink-swell
potential indicates hazards to the maintenance of structures constructed in, on,
or with such materials.
Essentially the shrink-swell potential of a soil refers to the potential for the soil to shrink or swell based on water retention rates. Or when there is more water in the soil it has a potenial to swell, when there is less water in the soil it tends to shrink. This can obviously cause problems for a foundation in that the soil underneath has the potential to change based on the amount of moisture in the soil.
Following is a list of the main soil types that cause problems for residential and commercial builders:
- Houston Black
The main limitations in use of the soils of this association in urbanization are the shrink-swell characteristics, as they affect foundations and streets.
The soils of this unit present problems when used in urbanization. There are special problems in designing and maintaining foundations, trafficways, other works of concrete and asphalt caused by a shrink-swell potential.
- Lewisville Soils
There are limitations to the use of this unit in urbanization. Some of the hazards are a shrink-swell potential that affects foundations and pavements.
- San Saba Soils
The use of this undifferentiated group for urban development presents problems. These problems are caused by the shrink-swell potential, as it affects design,
construction, or maintenance of concrete foundations and asphalt trafficways.
- Tarrant Soils
Soil characteristics that affect urban development are shrink-swell potential, as it affects foundations and paving.
- Urban Land and Austin soils/Urban Land, Austin, and Brackett soils
Some soil characteristics that affect urban development are shrink-swell potential, as it affects foundations and pavings.
- Urban Land and Ferris Soils
The use of this group for urban development is limited. Some of the soil characteristics that affect urban construction are shrink-swell potential, as it affects foundations and pavings.
- Volente soils and Urban Land
Some of the soil characteristics that affect urban construction are shrink-swell potential, as it affects foundations and paving.
Know your soil, and your potential for problems, before buying a house or deciding on foundation repair.
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