Foundation Repair GuideFree, source-cited foundation information

Foundation Problems by Region: Clay, Frost, Karst and High Water

Last reviewed October 28, 2026 · 10 sources cited

The same crack can mean different things in different places. Where you live decides which hazards are likely: shrink-swell clay, frozen ground, dissolving rock or rising water. This page maps hazards to causes and tells you where to look up your own address.

Hazards and where they matter

Hazard types and what the sources say. Regions are examples from the sources, not complete lists.
HazardWhat happensWhere the sources pointGuide
Expansive (shrink-swell) claySoil swells when wet and shrinks when dry, moving foundations unevenly.The NRCS 2004 publication discusses the Waco, Texas area and Colorado's Front Range;[1] USGS published a 1989 national swelling clays map.[2]Expansive clay soil
Frost heaveIce lenses form in frost-susceptible, moist soil and lift structures.Cold climates; design frost depth is set locally. HUD's FPSF research used test homes in Vermont, Iowa, North Dakota and Alaska.[3]Frost heave
Sinkholes and karstSoluble rock dissolves, leaving voids that can collapse.USGS says damage tends to be greatest in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee and Pennsylvania.[4]Sinkholes and karst
High water table and hydrostatic pressureWater pressure against walls and floors; wet crawl spaces and basements.Oak Ridge advises a slab-on-grade foundation where a crawl space floor could fall below the water table.[5]Water and drainage
Flooding, scour and erosionMoving water erodes soil around shallow foundations.FEMA says shallow foundations can be undermined by scour and erosion while deep foundations naturally resist it.[6]What is a foundation?

How to check your own address

  • Soil. The NRCS Web Soil Survey maps soils at an address, including shrink-swell information in survey reports.[7][1]
  • National swelling clay map. USGS Miscellaneous Investigations Series I-1940 (1989).[2]
  • Sinkholes and karst. Your state geological survey or equivalent publishes maps; USGS describes the national picture.[4]
  • Frost depth. Your local building department publishes the design frost depth, which sets minimum footing depth.[8]
  • Flood risk. FEMA flood maps and local floodplain managers; FEMA also publishes guidance on foundations in flood-prone areas.[6]

Soil varies over short distances, and published maps are coarse. A geotechnical engineer's borings on your lot are the definitive test, and local engineers and building officials know the local conditions best.

Why local practice differs

Foundation types follow the ground. In swelling clay, deep piers or engineered slabs are used to ride out moisture swings.[9][1] In freezing climates, footings go below frost depth or use insulation.[8] Where the water table is high, crawl spaces and basements need careful drainage or a different foundation type.[5] That is also why repair advice from another region may not fit your house.

State pages

This site started with Texas content and now covers the whole country. We do not yet have state-by-state pages, and we would rather build them with proper sources than copy boilerplate. For now there is one state guide: foundation repair in Texas, plus the Texas disclosure law page.

Common questions

Which parts of the country have the most foundation problems?

It depends on the hazard: expansive clay, frost, sinkholes and flooding each concentrate in different places. USGS says sinkhole damage is greatest in Florida, Texas, Alabama, Missouri, Kentucky, Tennessee and Pennsylvania,[4] and NRCS documents swelling-clay damage in places such as Waco, Texas and Colorado's Front Range.[1]

How do I find out what soil is under my house?

Start with the NRCS Web Soil Survey,[7] then ask a geotechnical or structural engineer about borings or local experience.

Does climate matter for foundations?

Yes: freezing climates add frost heave,[8] humid climates affect crawl space moisture,[10] and wet or dry swings drive clay movement.[9]

Expansive Clay Soil: Why It Damages Foundations and Where It IsHow swelling and shrinking clay moves houses, how widespread it is, and how to look up your soil.Frost Heave and Foundations in Cold ClimatesHow freezing ground lifts structures, what frost depth means, and how frost-protected shallow foundations work.Sinkholes and Karst: When the Ground Itself Is the ProblemHow sinkholes form, which states see the most damage, and what to do if you suspect ground collapse.Foundation Repair in Texas: Clay Soil, Engineering Guidelines and Local ContextWhat makes Texas foundation work distinctive, with the ASCE Texas Section guidelines, NRCS findings and disclosure law.

Sources

Figures and claims marked with a number come from these sources. Dates are the publication or last-update dates shown by the publisher, where one was shown. Older sources are flagged in the text.

  1. Understanding Soil Risks and Hazards. USDA Natural Resources Conservation Service, National Soil Survey Center; ed. Gary B. Muckel, 2004.Older (2004). Its statistic on expansive soils is attributed in the document to the American Society of Civil Engineers.
  2. Swelling clays map of the conterminous United States (USGS Miscellaneous Investigations I-1940). U.S. Geological Survey; W. W. Olive and others, 1989.The map itself is what to consult for regions; the catalog page has no abstract. Published in 1989.
  3. Frost-Protected Shallow Foundations, Phase II Final Report. U.S. Department of Housing and Urban Development, Office of Policy Development and Research; prepared by the NAHB Research Center, June 1994.1994 research report on new construction, not repair.
  4. Sinkholes (USGS Water Science School). U.S. Geological Survey; page dated September 17, 2026.
  5. Foundation Design Handbook, Section 3.1: Drainage. Oak Ridge National Laboratory (U.S. Department of Energy); undated.
  6. Hurricane and Flood Mitigation Handbook for Public Facilities, Fact Sheet 3.1: Foundations (FEMA P-2181). Federal Emergency Management Agency; March 2022.
  7. Web Soil Survey. USDA Natural Resources Conservation Service.A free map tool. Cited as a pointer to where soil survey data can be looked up; we did not extract figures from it.
  8. Protecting Foundations from Frost. Fine Homebuilding, issue 297; Glenn Mathewson; January 2021.Trade magazine article that cites International Residential Code sections.
  9. Home Construction on Shrinking and Swelling Soils (Special Publication 11). Colorado Geological Survey; Wesley G. Holtz and Stephen S. Hart, October 1978.Published in 1978. We use it for soil behavior and landscaping distances, not for costs or current practice.
  10. Unvented, Conditioned Crawlspaces (Building America Top Innovation). U.S. Department of Energy; January 7, 2014.