Soil Map of DallasThe soils your foundation is built upon matter when it comes to the structural integrity of your home.  Soil types can vary under a foundation, which makes knowledge of the soils around your home an essential part of home ownership. Some types of soil drain well and are stable, others drain poorly and move up and down.  Soils move up and down because they swell up when they absorb water and shrink when they dry out.  Such cycles are called shrink and swell cycles.

Soil Map of Dallas and the Surrounding Areas

According to the Texas Almanac, the soils in this region are considered Blackland Prairie soils. The USDA soil map and the National Resource Conservation Service (NRCS) add a great deal more detail.  In fact, the soils in the DFW metroplex vary from well drained sands to highly expansive, corrosive, soils with low load bearing capacity.

Texas Blackland Prairie Soils

The USDA and NRCS describe the active soils as clay-like in nature, something many homeowners will recognize. Here is how the United States Department of Agriculture (USDA) describes the black clays “This soil has low potential for urban uses.  The very high shrink-swell potential, corrosivity, and low strength of the soil are limitations.”   The high shrink/swell potential can be absolutely devastating to foundations, which need a firm, stable soil that doesn’t move much in order to retain their structural integrity.

Flood Plains Soils

Along the Trinity River and many creeks, the soils are flood plain soils.  These soils were deposited by the rivers.  Many of the soils in the flood plains contain expansive clays which exhibit a high rate of shrink and swell.  In some cases, the volume of the soil can change up to 30%.


Running from northeast Dallas County, down through Grand Prairie and Arlington is a broad band known as the Woodbine.  The Woodbine contains everything from sandy soils to some of the most unstable soils in Dallas.

Impact Of Soils on Foundations

These days, soils with high shrink and swell potentials are the most common reason foundations need repair. So, how do you know if you have expansive clay-like soils that may threaten the foundation of your home?  Look to see if the soils in your yard or the nearby soils in your neighborhood crack in the summer.  The bigger the cracks get, the more active the soils are.

If you notice cracking in your driveway or in the roadways by your house, or if the roads are uneven, that’s a pretty good sign that the soils underneath those areas are experiencing shrink and swell.  As soils become saturated, they swell.  As soils dry out, they shrink.   Movement causes cracks, which are pretty easy to see.  Swell is difficult to spot by the untrained eye — but if your driveway sits higher than your garage or your house, it’s a safe assumption that the soils on your property are swelling and pushing up the driveway, and possibly your home.

Evaluating Soils and Determining if You Need Foundation Repair

Sometimes, it is pretty obvious that your house needs some work done on the foundation. Most of the time, it is not. In order to ensure your home stays safe for you and your loved ones, it’s important to leave this work to the professionals. Contact Advanced Foundation Repair today for a free, precise inspection. With years of experience, a transferable lifetime warranty, and the willingness to work with you on a payment plan to make sure your home gets the repairs it needs, you won’t be disappointed.