★FOUNDATION GUIDE★
Spring, TX soil and what it does to foundations
Spring sits on two old Gulf Coast geologic layers. The upper one is expansive clay that swells when wet and shrinks when dry, and it is the main reason foundations here move.
The two layers under Spring
- ★ Beaumont FormationPlastic, compressible clay and mud laid down in flood basins, coastal lakes and old stream channels. In the Houston area this clay can be up to 40 feet deep. It is the main troublemaker.
- ★ Lissie FormationOlder and sandier: sand, silt, clay and some gravel, sitting beneath the Beaumont. Both are mapped in Harris and Montgomery counties, Spring's two counties.
- ★ Why it varies street to streetSpring sits near where the clayey and sandier ground meet, so soil conditions can change over short distances. Two neighboring homes can behave differently.
How expansive is it?
A University of Houston study of Houston-area clays measured:
- ★ High-plasticity clay (CH)Average liquid limit of 59% and plasticity index (PI) of 34%.
- ★ Lower-plasticity clay (CL)Average liquid limit of 38% and PI of 20%.
- ★ What PI meansA higher plasticity index means more swelling and shrinking. A PI over 50 is considered highly plastic and very expansive.
- ★ The causeExpansive soils contain smectite clay minerals, which absorb water between their layers and change volume.
Reach out
Estimates and site visits are free. You get a written report and price before any work starts, and we'll walk you through your options so you can decide what's right for your home.