St. Louis, MO · St. Louis County · USDA soil survey 2026-08-28
Foundation repair in St. Louis, MO: what the soil says, what it should cost
The soil under St. Louis County is mostly moderately well drained; shrink-swell is moderate (LEP 3.47%), so St. Louis foundation problems are usually water and pressure, not expansive clay. Published national ranges put a typical repair at $2,224–$8,134, piers at $1,000–$3,000 each. Check the soil under your own address below; then read what an independent engineer costs before you sign.
- Moderately well drained soil
- 84 map units with data
- Every price cited
- No contractor rankings
How much do basement waterproofing and foundation repair cost in St. Louis?
We do not have St. Louis-specific price data and won't invent an “average for St. Louis.” What published national guides report, with the figures the guides themselves publish:
- Typical job: $2,224–$8,134, average $5,179. Source: This Old House — Foundation Repair Cost, updated 2026-03-06
- Piering / underpinning: $1,000–$3,000 per pier. Source: This Old House — Foundation Repair Cost, updated 2026-03-06
The pier count and depth move a St. Louis number, and they depend on the soil under that specific house and how far down stable material sits. On this soil, the cheaper fixes (drainage, grading, leak repair) are more often the right answer than a pier plan.
| Repair | Published range | Source |
|---|---|---|
| Crack repair (epoxy / polyurethane injection) | $250–$800 per crack | Bob Vila — How Much Does Foundation Repair Cost?, updated 2024-05-29 |
| Wall stabilization / reinforcement (carbon fiber or steel, ~12 strips) | $4,000–$12,000 per job | This Old House — Foundation Repair Cost, updated 2026-03-06 |
| Bowed wall repair (all methods) | $5,000–$15,000 per job | Bob Vila — How Much Does Foundation Repair Cost?, updated 2024-05-29 |
| Foundation sealing / waterproofing | $2,300–$7,300 per job | This Old House — Foundation Repair Cost, updated 2026-03-06 |
| Drainage system | $2,800–$6,500 per job | Bob Vila — How Much Does Foundation Repair Cost?, updated 2024-05-29 |
Holding a St. Louis quote? Read it against the St. Louis County soil record before you sign.
What the soil under St. Louis County does
Source: USDA NRCS SSURGO, county legend MO189, top 152 cm, weighted by mapped acreage. Coverage: 91% of mapped acres carry usable data across 84 map units. Built 2026-08-28.
- very high1%
- high3%
- moderate69%
- low27%
Drainage class (acre-dominant): Moderately well drained. Hydrologic group: C (D = slowest infiltration, highest runoff). Water table (annual minimum depth, cm): 81. Flooding: None.
The largest mapped unit in St. Louis County is Urban land-Harvester complex, 2 to 9 percent slopes (22% of surveyed acres, moderate, LEP 3.6%, moderately well drained); next is Urban land-Harvester complex, 9 to 20 percent slopes at 10%, moderate with LEP 3.6%.
SSURGO survey MO189 is 'St. Louis County and St. Louis City'; the city has no separate legend.
Where the expansive soil is: largest map units in St. Louis County
The hyper-local view: St. Louis neighborhoods sit on different ground, and the address lookup tells you which unit is under a given house.
| Map unit | Share of surveyed acres | LEP | Class | Drainage |
|---|---|---|---|---|
| Urban land-Harvester complex, 2 to 9 percent slopes | 22% | 3.6% | moderate | Moderately well drained |
| Urban land-Harvester complex, 9 to 20 percent slopes | 10% | 3.6% | moderate | Moderately well drained |
| Urban land-Harvester complex, karst, 2 to 9 percent slopes | 5% | 3.6% | moderate | Moderately well drained |
| Menfro silt loam, 20 to 45 percent slopes | 5% | 3.93% | moderate | Well drained |
| Fishpot-Urban land-Freeburg complex, 0 to 2 percent slopes, frequently flooded | 4% | 2.87% | low | Somewhat poorly drained |
| Urban land-Harvester complex, 0 to 2 percent slopes | 3% | 3.6% | moderate | Moderately well drained |
| Gasconade-Rock outcrop complex, 15 to 50 percent slopes, rubbly | 3% | 7.5% | high | Somewhat excessively drained |
| Goss very gravelly silt loam, 14 to 45 percent slopes | 3% | 1.85% | low | Well drained |
| Menfro silt loam, 9 to 14 percent slopes, eroded | 3% | 3.72% | moderate | Well drained |
| Urban land-Fishpot complex, 0 to 2 percent slopes, occasionally flooded | 2% | 2.71% | low | Somewhat poorly drained |
Check the soil under an address
USDA soil survey, read for the top 60 inches under the address. Free, no account, nothing is sent to a contractor.
Usually 1–3 seconds. The USDA service occasionally takes longer.
Is it worth waterproofing a basement in St. Louis? Do you actually need this?
Around here the soil story is water, not swelling clay: seasonally high water tables and slow drainage push water and pressure against basement walls.
- Wet basement quotes split into drainage/waterproofing (thousands) and wall stabilization (more). Make sure you know which one you're being quoted.
- Bowing walls are structural and deserve an engineer's measurement; damp walls usually don't.
- Interior drain-and-sump systems and exterior grading fix most water problems; carbon-fiber or steel is for walls that have actually moved.
We are not engineers and this is not an engineering opinion. We report public soil-survey data and published price ranges. Nothing here states that a specific house is or is not structurally sound; a licensed structural engineer who has seen the house can.
Does homeowners insurance cover basement waterproofing or foundation repair in Missouri?
Usually no. Standard homeowners policies exclude earth movement (settling, shrinking, expanding and cracking of the foundation), so damage from expansive soil is not covered. Damage that results from a covered sudden event, such as a burst pipe flooding under a slab, can be, and separate earthquake or flood policies cover those perils.
Full answer for Missouri → Source: HO-3 Special Form policy text (exclusion: "settling, shrinking, bulging or expansion, including resultant cracking, of pavements, patios, foundations, walls, floors, roofs or ceilings"), as filed with the Oklahoma Insurance Department
Finding a structural engineer in St. Louis for an independent opinion
A contractor's free inspection produces a bid. A licensed structural engineer who does not sell repairs produces the scope that bid should be written to: whether movement is active, what is causing it, and the pier count and depth if any. Published cost: $300–$1,000. Source: Bob Vila — How Much Does Foundation Repair Cost?, updated 2024-05-29
People in St. Louis search for a structural engineer about 390 times a month, more than they search for a “foundation inspection” (10). Verify a license with the Missouri board; what the report should contain →
Foundation repair types people in St. Louis search for
Monthly Google searches for each phrase with “St. Louis” attached (Google Ads, pulled 2026-08-28). Each links to the cited cost range and when that repair is the right one.
- Basement waterproofing in St. Louis, about 260/mo: gutters, downspouts and grading before any system; interior drain and sump on slowly drained soil.
- House leveling in St. Louis, about 10/mo: a sales word, not a method. It means either piers or slabjacking, which are priced very differently; ask which.
- Crawl space repair in St. Louis, about 10/mo: water first, then framing and piers; encapsulation only once it is dry from outside.
Finding and comparing foundation repair companies in St. Louis
Google shows a map pack of 3 contractors for “foundation repair St. Louis”; we don't rank them and don't take money to list them. A good bid and an aggressive one differ in scope, not in company name, so get the engineer's scope first and have every St. Louis company bid to it. On this soil drainage is usually the fix, and a bid with no drainage line is incomplete. What a comparable quote itemizes →
St. Louis foundation repair: questions people ask
How much does foundation repair cost in St. Louis?
We don't have St. Louis-specific price data. Published national figures put a typical job at $2,224–$8,134 (average $5,179); piers run $1,000–$3,000 each, and the pier count is what moves a St. Louis quote.
Does homeowners insurance cover foundation repair in Missouri?
Usually no. Standard homeowners policies exclude earth movement (settling, shrinking, expanding and cracking of the foundation), so damage from expansive soil is not covered. Damage that results from a covered sudden event, such as a burst pipe flooding under a slab, can be, and separate earthquake or flood policies cover those perils.
Is it worth waterproofing a basement in St. Louis? Do I actually need it?
Around here the soil story is water, not swelling clay: seasonally high water tables and slow drainage push water and pressure against basement walls.
What is the cheapest way to waterproof a basement in St. Louis?
Start outside: gutters, downspout extensions and grading away from the wall are the cheapest interventions and are where most water comes from. An interior drain and sump is the durable fix on slowly drained soil (hydrologic group C/D), and exterior excavation is the most expensive option. Price them in that order.
Will insurance pay for basement waterproofing?
Almost never as a preventive job. Usually no. Standard homeowners policies exclude earth movement (settling, shrinking, expanding and cracking of the foundation), so damage from expansive soil is not covered. Damage that results from a covered sudden event, such as a burst pipe flooding under a slab, can be, and separate earthquake or flood policies cover those perils.
How do I compare foundation repair companies in St. Louis?
Get an independent engineer's report first, then have every company bid to that scope: same pier type, count and depth. Compare the warranty terms (transferable? covers the house or only the pier?) and the moisture plan, not the sales pitch. We don't rank contractors.
Where do I get an independent opinion in St. Louis?
A licensed structural engineer who is not selling the repair. A report costs about $300–$1,000 and specifies whether movement is active and what work, if any, is warranted.
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