Why Do Foundations Crack in Denton County?
Denton County sits in the upper middle on clay and has the most land in extreme drought right now.
Foundations crack in Denton County because 60.6% of the rated soil, by acre, is high or very high shrink-swell clay, and the county is in a dry stretch now: the Drought Monitor map dated 2026-10-13 puts 20.87% of Denton County in extreme drought (D3) or worse, the largest share of the seven counties. HGS Engineering, PLLC (Texas Firm #21268) prints both here.
Reviewed by Heath Salmon, PE, October 16, 2026. Soil data downloaded 2026-10-16, drought data downloaded 2026-10-16.
What Does the Soil Survey Say About Denton County?
The split is 17.7% low, 21.7% moderate, 43% high and 17.5% very high. Denton County is unusual in leaning on the high class rather than very high, so the soil is active but less extreme than Collin or Ellis County.
The cracking mechanism is the same as in every clay county: water content changes the volume of the soil, and the slab above follows unevenly.
The firm has a Lewisville page for the county. Requests from anywhere in Denton County come in by email.
| Class | Rated acres | Share of rated acres |
|---|---|---|
| Low | 91,196 | 17.7% |
| Moderate | 111,766 | 21.7% |
| High | 221,357 | 43% |
| Very high | 90,191 | 17.5% |
| High plus very high | 311,548 | 60.6% |
| Not rated (urban land, water, pits) | 98,649 | 16.1% of all acres |
| Rank among the seven counties, high plus very high | 4 of 7 | |
Which Denton County Soils Carry the High Ratings?
Sanger leads with 66,673 acres of high or very high rating, followed by Ponder (25,601), Slidell (25,456), Navo (23,977) and Frio (22,025). The table shows the top five from 217 components.
16.1% of the county has no rating, mostly urban land and water.
| Soil name | High or very high acres |
|---|---|
| Sanger | 66,673 |
| Ponder | 25,601 |
| Slidell | 25,456 |
| Navo | 23,977 |
| Frio | 22,025 |
How Dry Has Denton County Been Since 2021?
Denton County had some land in D2 or worse in 67 of 262 weeks between 2021-10-12 and 2026-10-13, half or more in 45 weeks and half or more in D3 or worse in 13 weeks, the fewest of the seven. The calendar counts of weeks with any D2 were 34 in 2022, 23 in 2023 and 8 so far in 2026.
The latest map shows 41.42% of the county in D2 or worse and 20.87% in D3 or worse. A county with active clay that is this dry now is one where a heavy autumn rain could move slabs fast.
| Weeks counted | 262 |
|---|---|
| Weeks with any land in D2 (severe) or worse | 67 |
| Weeks with half or more of the county in D2 or worse | 45 |
| Weeks with half or more in D3 (extreme) or worse | 13 |
| Mean share of the county in D2 or worse | 16.5% |
| Latest week (2026-10-13): in D2 or worse, in D3 or worse | 41.42% and 20.87% |
| Weeks with any D2 in 2021 | 0 |
| Weeks with any D2 in 2022 | 34 |
| Weeks with any D2 in 2023 | 23 |
| Weeks with any D2 in 2024 | 2 |
| Weeks with any D2 in 2025 | 0 |
| Weeks with any D2 in 2026 | 8 |
What Does an Inspection Do With This Information?
The engineer looks at the house, not the map. Grade, gutters, plumbing near the slab, trees, floor levels and cracking are what the report records. A rapid change in moisture is the situation in which the report's drainage section becomes the part a homeowner uses first.
The firm performs no repairs, and a quote for the inspection comes by email on request.
See the foundation inspection service page or use the request form.
How Were These Numbers Made?
Method: for each soil component in the Denton 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 Denton County?
- Foundation inspection in Lewisville, TX
- Foundation inspection service
- Other counties: Tarrant, Dallas, Johnson, Ellis, Parker, Collin
Frequently Asked Questions
Why do foundations crack in Denton County?
60.6% of rated acres are high or very high shrink-swell clay, and the ground goes through wet and dry cycles. The slab above it moves unevenly with the water.
How dry is Denton County now?
The Drought Monitor map dated 2026-10-13 shows 41.42% of the county in D2 or worse and 20.87% in D3 or worse.
Does the firm serve Lewisville and the rest of Denton County?
Yes. The firm has a Lewisville page and takes requests across the county by email.
Are the figures current?
The soil survey was pulled on 2026-10-16 and the drought statistics on 2026-10-16. Drought maps update weekly, so the current week may differ.
Sources
- USDA Natural Resources Conservation Service, Soil Data Access web service (SSURGO tabular data)Linear extensibility (lep_r), map unit acres and component percent for the seven counties, queried on 2026-10-16.
- National Drought Mitigation Center, University of Nebraska-Lincoln, U.S. Drought Monitor data services, county statisticsWeekly percent of each county in D2 (severe) or worse and D3 (extreme) or worse, October 2021 to October 2026.
- Texas Board of Professional Engineers and Land Surveyors, Engineering Firm RegistrationThe firm registration number and the licensed engineer seal.
- Texas Section, American Society of Civil Engineers, Guidelines for the Evaluation and Repair of Residential Foundations, Version 3Foundation evaluation practice, drainage away from the foundation and North Texas soil movement.
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