MoCo Foundation Repair Montgomery County, Texas Request inspection
We are not a contractor. Inspections and repairs are performed by an independent, licensed and insured local partner contractor, who will be named on this site once selected. (XXX) XXX-XXXX Phone number coming soon — Calls may be recorded.

Home / Soil and drainage

Soil, trees, and drainage in Montgomery County

Two reputable local writeups describe Montgomery County soil differently. The overlap is what matters for homeowners: moisture changes, trees, drainage, and fill can move a house even when the lot is not classic Houston black clay.

The disagreement, stated plainly

In July 2017, professional engineer Drew Dudley wrote for the Greater Houston Builders Association that soils in Montgomery County “tend to be highly expansive,” that the county’s climate cycle reflects moderate to intense dry-moisture swings, and that this combination is “the perfect recipe for substantial soil movement.” He treats foundation design as a local engineering issue, not a rarity, and discusses Type III “rigid raft” slabs as a response to soil that is going to move.

In a 2026 county guide, Texas Tough describes a different map. Summarizing USDA NRCS soil-survey (SSURGO) data, it says about 95 percent of the county lies in the South Central Plains (Piney Woods), that most soils are loamy or sandy, and that only about 15 percent of the land is high or very high shrink-swell, compared with about 47 percent in Fort Bend County. It lists Conroe (about 15 percent of the county, plasticity index around 17, moderate swell), Fetzer (about 9 percent, PI around 16, low swell), Splendora (about 7 percent, PI around 12, low swell), and Woodville (about 6 to 7 percent, PI around 41, high swell) among the common mapped soils.

Those two pictures are not identical. This site does not pick a winner. We cite both, because a homeowner searching for answers should know that “Montgomery County is all expandable clay” and “Montgomery County is barely clay at all” are both oversimplifications of published local writing.

Woodville clay, from the USDA series description

The official USDA-NRCS series description for Woodville soils says they are deep, somewhat poorly drained, and very slowly permeable, formed in clayey coastal-plain sediments. Clay content in the upper part of the subsoil ranges from 40 to 60 percent. The description states that the soil has high shrink-swell potential and vertic properties, a coefficient of linear extensibility (COLE) of 0.09 or more, and potential linear extensibility of more than 6 centimeters. The type location is in Jasper County, Texas, not Montgomery County; the series is mapped in southeastern Texas and southwest Louisiana. Native vegetation listed in the description includes loblolly, shortleaf, slash, and longleaf pines with hardwoods such as sweetgum, red oak, and hickory.

That official language is why Texas Tough flags Woodville as “the soil to watch” even while saying high-swell ground is a minority of the county. A house on a Woodville inclusion can behave like a Houston clay house. A house on a sandy or loamy map unit a short distance away may not.

Local photo coming soon

If you can do so safely and legally, photograph exposed subsoil on a local construction cut, a cracked clay surface in dry weather, or the contrast between sandy topsoil and a heavier subsoil. Do not enter active construction sites.

A real Montgomery County soil or lot-grade photo will serve this page better than a downloaded clay illustration.

Trees

Both sources treat trees as a first-order issue. Dudley’s GHBA article says trees and large bushes close to a foundation can remove water and create a moisture imbalance, and it recommends planting a tree about half its canopy diameter away from the foundation and/or installing a root barrier. Texas Tough says large pines and hardwoods, from Sam Houston National Forest to wooded subdivisions near Lake Conroe, can dry soil under a slab in a dry summer and drop the nearest slab edge, especially on clayey ground.

Removing a healthy tree is not automatically the right repair. It can also change soil moisture in the other direction. Ask an inspector or an arborist before you cut.

Drainage and building pads

The GHBA article lists several factors that affect every slab-on-grade foundation, whether or not it was custom-engineered:

  • Building pad: a geotechnical engineer may recommend removing high-expansive native soil and replacing it with select fill. The pad’s moisture at the time of pour matters; a saturated pad has more room to shrink later than to swell.
  • Drainage: water that ponds against one section of the house can raise moisture on that side and contribute to uneven movement.
  • Moisture maintenance: the article recommends keeping moisture around the foundation as uniform as possible, including gutters that outfall well beyond the slab and adding moisture during dry periods.
  • Landscaping: tree and shrub placement, as noted above.

Texas Tough adds two county-specific drainage notes: on sandy soil, runoff on a sloped lot can wash soil from under a corner; and floods along the West Fork of the San Jacinto River and Spring Creek can saturate ground that later dries and shifts. It also states that Montgomery County is outside the Harris-Galveston Subsidence District and that subsidence has been less severe here than in Harris County.

New construction and fill

Census Bureau QuickFacts report 13,614 building permits in Montgomery County in 2025 and estimate the county population at 781,194 as of July 1, 2025. About 71.8 percent of occupied housing units were owner-occupied in 2020-2024. Texas Tough, using American Community Survey figures, says about 60 percent of homes were built in 2000 or later and that the median home dates to 2004. Its list of how young slabs fail starts with settlement over fill on cut-and-fill lots and drainage that was never finished.

If you bought a recently built house, unfinished grade and fill settlement belong on the inspection checklist alongside any conversation about clay.

What this means if you are deciding whether to inspect

You do not need a soil-survey map in hand to request a look at the house. You do need to be wary of anyone who diagnoses your lot from a city name alone. See warning signs, then request an inspection if you want measurements. Inspections are performed by [Partner contractor name TBD], not by MoCo Foundation Repair.

Sources cited on this page