Why Do Foundations Crack in Dallas County?

What Does the Soil Survey Say About Dallas County?

Dallas County has fewer rated acres than Ellis or Collin, but a big share sits at the top of the scale. Low is 13.2% of rated acres, moderate 22.9%, high 19.5% and very high 44.4%. Very high means a clod of the soil grows nine percent or more in length from dry to wet. A slab on that cannot stay level when the water reaches it unevenly.

Much of the county is built over. 31.4% of its land has no rating at all, because it is urban land, water or other disturbed ground, the largest unrated share of the seven counties. Under many houses the dirt is fill that a builder trucked in, and the survey does not describe fill. The table speaks for the clay around the built-up areas.

Irving and Grand Prairie are the two cities this site files under Dallas County, and the firm's city pages for both carry Census housing age next to these soil figures. A house built before 1980 on a very high shrink-swell clay has been through more wet and dry swings than a recent one, and its history of repair matters to the engineer.

Which Dallas County Soils Carry the High Ratings?

Houston Black leads at 67,795 acres in the high and very high classes, followed by Trinity (45,920), Heiden (25,309) and Ferris (21,751). The table shows the top five. Houston Black is the single largest contributor in the county.

The survey rates 203 components in the county. Each one's acreage is its map-unit acres times its percent of the unit, then summed by soil name.

How Dry Has Dallas County Been Since 2021?

Dallas County had some land in D2 (severe drought) or worse in 61 of 262 weeks between 2021-10-12 and 2026-10-13, half or more of the county in 37 weeks, and half or more in D3 (extreme) in 18 weeks. The mean share of the county in D2 or worse across the whole period is 15.4%.

By calendar year the count of weeks with any D2 was 34 in 2022, 18 in 2023, 1 in 2024, 0 in 2025 and 8 so far in 2026. The latest map, dated 2026-10-13, shows 68.52% of the county in D2 or worse and 3.96% in D3 or worse. A very high shrink-swell clay in the middle of that drying is the setting for most of the cracking reports the firm hears about.

What Does an Inspection Do With This Information?

The engineer takes the soil figures as a starting guess and then looks at the house. The report records floor levels, how doors and windows close, cracks in brick and drywall, the grade at each wall and where every downspout empties. If there is an old repair, the report names its type and says whether the house is still moving around it.

HGS Engineering does not perform foundation repairs, so a homeowner who later hires a repair contractor has an independent sealed report to hand over.

See the foundation inspection service page or use the request form.

How Were These Numbers Made?

Method: for each soil component in the Dallas County SSURGO survey, the script averages linear extensibility over the top 100 centimeters, weighted by horizon depth. The average puts the component in an NRCS class: low under 3 percent, moderate 3 to under 6, high 6 to under 9, very high 9 or more. Acres are the map unit's acres times the component's percent of the unit, and components with no reading are left out of the percentages. The Drought Monitor figures are weekly county statistics. Both raw pulls are committed with the scripts, and a gate re-runs them before each build. A soil survey describes a county, never a single lot.

Where Does the Firm Work in Dallas County?

• Foundation inspection in Grand Prairie, TX
• Foundation inspection in Irving, TX
• Foundation inspection service
• Other counties: Tarrant, Johnson, Ellis, Parker, Denton, Collin