Quick answer
Foundation subsidence is the downward movement of a foundation because the ground it sits on has lowered. The ground can drop over a wide area or in a small patch, and the building goes down with it.
The term comes from geology, where land subsidence means the gradual settling or sudden sinking of the Earth’s surface. A house is one thing that can ride along.
Quick facts
The key facts about Foundation Subsidence, with sources:
- Direction
- Down; the ground surface itself lowers 1
- Scale
- More than 17,000 square miles in 45 states have been directly affected by land subsidence 1
- Main cause
- Human use of underground water accounts for more than 80 percent of identified U.S. subsidence 1
- Other principal causes
- Drainage of organic soils, underground mining, hydrocompaction, natural compaction, sinkholes, thawing permafrost 1
- Speed
- Gradual settling or sudden sinking, depending on the cause 1
- Soil-survey meaning
- Settlement of organic soils or very low density saturated mineral soils after drainage 2
- Page type
- Definition; the building-level term is foundation settlement
Key takeaways
- Subsidence means the ground lowers. The foundation sinks because what holds it up has gone down 1.
- The U.S. Geological Survey ties more than 80 percent of identified subsidence in the U.S. to human use of underground water 1.
- Other causes include drained organic soils, mine collapse, sinkholes and thawing permafrost 1.
- Subsidence can be slow and wide, or sudden and local. Both show up in a house as cracks, sloping floors and sticking doors.
- The cause sits underground. Only a qualified professional with soil information can tell subsidence from ordinary settlement.
Subsidence starts below the house, not in it
Land subsidence, in the words of USGS Circular 1182, is the gradual settling or sudden sinking of the Earth’s surface, caused by movement of materials below it 1. When the lowered ground carries a house, the house goes down too. That is foundation subsidence.
The word is easy to mix up with settlement. A useful split is scale and source. Subsidence is about the ground losing volume or support, often over a large area, from something that happened underground.
Settlement is the more general word for a building moving down, and it also covers soil that compresses under the house’s own weight. See foundation settlement for that wider term.
The USDA soil survey uses the word more narrowly. In its engineering notes, subsidence is the settlement of organic soils or of saturated mineral soils of very low density, usually following drainage. It takes place gradually, usually over a period of several years 2.
General information, not a diagnosis of your house
General information, not a diagnosis of your house. Whether subsidence is behind a crack or a sloping floor is a question for a licensed professional who has seen the building and the ground.
The principal causes of subsidence
| Cause | What happens underground | What a professional checks |
|---|---|---|
| Aquifer-system compaction | Heavy pumping lowers groundwater levels and the water-bearing sediments compact 1 | Regional records of water-level change and local land-surface data |
| Drainage of organic soils | Peat and similar soils shrink and break down once drained 12 | Soil survey, depth to organic layers, drainage history |
| Underground mining | Voids left underground can collapse 1 | Mine maps and state mining records |
| Hydrocompaction | Named by USGS as a principal cause 1 | Geotechnical evaluation of the site |
| Natural compaction | Sediments settle under their own weight over time 1 | Soil borings and past movement records |
| Sinkholes | Soluble rock such as limestone, gypsum or salt dissolves and the cover soil falls in 1 | Geologic maps and a geotechnical investigation |
| Thawing permafrost | Ice in frozen ground melts and the ground drops 1 | Regional permafrost mapping |
Two panels. Left: soil under a house compresses and the house moves down. Right: soil under a house swells and the house is pushed up. Arrows show the direction of movement.
Illustrative, not to scale, not a design. The sinking side shows the idea of subsidence; the rising side is its opposite, heave.
How subsidence turns into house damage
- Something below changes. Water is pumped out, a mine roof gives way, organic soil is drained, or rock dissolves 1.
- The ground surface drops. This can be gradual over years or sudden in a collapse 1.
- The footing loses support. If the whole ground drops evenly, the house goes down as a unit. If only part drops, one part of the foundation loses support.
- The frame is racked. The uneven part pulls on walls, floors and roof framing. Cracks, sticking doors and sloping floors may follow. See differential settlement.
- Water finds new paths. Cracks and gaps let more water in, which can add to the problem.
In a large, even drop the house may show little damage. In a small, uneven drop it may show a lot. The pattern, not just the amount, is what an engineer reads.
Example: reading USGS’s numbers
USGS gives a national picture, not a house-level one. This example reads its published figures 1 to show what they do and do not say.
| Published statement | What it tells you | What it does not tell you |
|---|---|---|
| More than 17,000 square miles in 45 states directly affected | Subsidence is not rare or limited to a few places | Whether your lot is affected |
| USGS lists seven principal causes, starting with aquifer-system compaction | Subsidence has more than one source | Which cause applies to any single crack |
| More than 80 percent of identified subsidence links to human impact on subsurface water | Most subsidence is tied to water management, not to the house | How fast your ground is moving |
| Sinkholes are often overlooked in humid areas on soluble rock | Rock type matters even in wet climates | Whether a void exists near you |
USGS’s page does not describe damage to buildings. For house-level answers you need local maps, soil data and an engineer’s eyes.
Where subsidence is a concern
Subsidence turns up in four kinds of place. Areas with long-term groundwater pumping are the biggest group. Drained farmland or marsh with organic soils is the next. Sites over old mines are a third, and land on soluble rock such as limestone, gypsum or salt is the fourth 1.
Inside a house, the signs overlap with other kinds of movement: gaps between walls and ceilings, doors that stop closing, cracks above windows, and floors that slope. A crack alone does not say why the ground moved. Our foundation cracks guide covers how crack patterns are read, and why they are clues, not diagnoses.
Why the label helps, and where it stops
What the word gets you
What it does not settle
- It does not prove that your house is subsiding. Ordinary settlement and heave can look similar.
- It does not say whether movement is continuing.
- It does not choose a fix. Any repair depends on loads, soils and an engineer’s design.
What this definition does not cover
- The subsidence definition does not include soil that swells upward. That is foundation heave.
- It does not include a footing that is too small for its load. That is a design or bearing problem, not ground loss.
- It does not predict where the next sinkhole will form. USGS notes that pumping can trigger collapse, and one Florida irrigation well was followed by hundreds of sinkholes over a small area, but local hazard is a matter for geologic study 1.
- It gives no thresholds for “normal” movement. None appear in the sources and none should be invented.
What drives cost when subsidence is suspected
We do not give a price, because repair cost follows the answers to questions nobody can answer without a site visit. Is the ground still dropping? How deep is the unstable layer? How much of the house has moved? Can the work reach stable material?
Investigation can cost money before any repair is chosen: soil borings, lab tests, a survey of floor levels and sometimes a geotechnical report. That work is how a professional learns whether the cause is subsidence, settlement or something else. See geotechnical soil investigation.
For an estimate shaped by your own inputs, use the cost calculator and read the cost guide.
What a homeowner can do first
- Write down what you see. Note cracks, sloping floors and sticking doors, with dates.
- Photograph cracks with a ruler or coin in the frame, and repeat the photo from the same spot over time.
- Ask the neighbors. Subsidence often affects an area, so similar problems nearby are a clue.
- Check the water. Look for leaks, pooling and downspouts that dump at the wall, and fix surface water you can safely control.
- Use the elevation log and inspection checklist to keep a tidy record for a professional.
- Ask a licensed structural engineer to assess the house if movement is significant or changing. A geotechnical engineer may be needed for the ground.
Do not dig, jack or probe near the foundation yourself
If a void or sinkhole is possible, keep people and vehicles back and call a professional. Do not dig next to a foundation, jack a floor, or enter a crawl space with standing water, gas or electrical hazards.
Habits that help once the cause is known
- Keep a dated log of cracks and floor levels. A pattern over months says more than one reading.
- Keep gutters clear and downspouts discharging away from the wall. See downspout drainage.
- Fix plumbing leaks quickly. A leaking line can wash out soil under a slab. See plumbing leaks and foundation damage.
- Report new sinkhole-like depressions in the yard to your local building or emergency office, and keep clear of them.
- Keep records of any engineer’s report. They matter when you sell or insure.
Risks if subsidence goes unchecked
The main risk is that the movement continues. Where the cause is regional, such as long-term pumping, the ground may keep dropping on a timescale a homeowner cannot control 1. Repairs aimed at one house cannot promise the ground stays still.
A second risk is sudden collapse. USGS describes sinkholes among subsidence causes and notes that pumping can trigger collapse 1. A depression that opens or deepens quickly is a safety issue, not a maintenance chore.
A third risk is financial. Standard homeowner’s insurance often has exclusions for earth movement and soil-related damage. Coverage depends on policy wording, cause and state law. Read your policy and ask your insurer. See our insurance guide.
When to call a licensed structural engineer
Call when movement is significant, widening or changing; when walls are displaced or bowing; when new cracks come with sticking doors or windows; when walls separate at corners; or if you doubt the safety of the house. Do I need a structural engineer?
Rules, records and who deals with subsidence
There is no single national rule for subsidence. The model International Residential Code asks for soil information where soils may be compressible or shifting; the Texas state bulletin on expansive soils quotes IRC section R401.4 for that purpose, and says the code offers alternatives to a full geotechnical evaluation 3.
That text is about soil tests during design, not about repairs to a house already moved.
Local rules often cover groundwater use, mining and sinkhole hazard areas. They differ by state and county. Ask your building department and your state geological survey what applies at your address.
The edition and adoption of the IRC vary. Check the code your jurisdiction adopted.
Edition and adoption
The IRC section cited comes from the 2015 edition as quoted in a Texas state bulletin. Your jurisdiction may use another edition or add amendments.
Subsidence compared with its close relatives
| Term | What it means | Scale |
|---|---|---|
| Subsidence | The ground surface lowers 1 | Often wide-area; can be local |
| Foundation settlement | A foundation moves down for any reason | Building-level |
| Soil consolidation | Water leaves loaded soil and it compresses slowly 4 | Under one building or one fill |
| Foundation heave | The ground rises 3 | Local to wide |
| Sinkhole | Ground collapses into a void in soluble rock 1 | Local, can be sudden |
Myths about subsidence
- Myth Subsidence is the same as settlement.
- Reality Settlement is the broader word for a building going down. Subsidence names a loss of ground level, often from something underground 1.
- Myth It only happens in a few dry states.
- Reality USGS counts affected land in 45 states, and notes it is often overlooked in humid areas on soluble rock 1.
- Myth A sinkhole always gives warning.
- Reality Subsidence can be a sudden sinking as well as a gradual settling 1.
- Myth Fixing the house fixes the cause.
- Reality A repair at one house does not change regional causes such as groundwater levels.
- Myth Subsidence is always covered by insurance.
- Reality Coverage depends on the policy and state law. Many policies exclude earth movement.
Regional drivers
Which cause matters depends on where you are. USGS ties most identified subsidence to groundwater use, and lists sinkholes on soluble rock as a hazard in humid areas such as west-central Florida, with the Sacramento–San Joaquin Delta and the Florida Everglades as case studies of drained organic soils 1.
Check your state geological survey for maps of mines, karst and sinkhole risk.
Choosing your next step
Use the guide to match what you see with a sensible first call.
- If One small crack, no other signs
- Then Photograph, date and monitor it
- If Several cracks plus sloping floors in a neighborhood with similar reports
- Then Ask a licensed structural engineer; ask whether a geotechnical review fits
- If A depression or hole opening in the yard
- Then Keep clear and call local authorities and a professional
- If Walls displaced or a rapid change
- Then Call a licensed structural engineer promptly
Engineer before contractor
Ask a licensed engineer to assess before you commit to any repair work. Try the engineer-or-contractor tool.
Questions about Foundation Subsidence
What is foundation subsidence?
Foundation subsidence is a foundation moving down because the ground beneath it has lowered. USGS defines land subsidence as the gradual settling or sudden sinking of the Earth’s surface from movement of underground materials 1. A house on that ground goes down with it.
What is the difference between subsidence and settlement?
Settlement is the general word for a building going down, including soil that compresses under its weight. Subsidence names the ground surface itself dropping, often from an underground cause. In daily use the two overlap, so a professional has to separate them using soil and site records 12.
What causes the ground to subside?
USGS lists aquifer-system compaction, drainage of organic soils, underground mining, hydrocompaction, natural compaction, sinkholes and thawing permafrost. More than 80 percent of the identified subsidence in the U.S. is a consequence of exploiting underground water 1.
How much of the United States has subsided?
USGS reports more than 17,000 square miles in 45 states directly affected, an area about the size of New Hampshire and Vermont combined 1. That number covers land, not houses, and says nothing about any one address.
What are the signs of a subsiding house?
Signs overlap with other movement: cracks in walls or above doors and windows, sloping floors, gaps at trim, and sticking doors. None proves subsidence. Because causes differ, a pattern recorded over time, plus soil and site information, is more useful than any single sign.
Can subsidence happen suddenly?
Yes. USGS describes land subsidence as gradual settling or sudden sinking, and counts sinkholes among its causes 1. A hole or depression that opens or grows quickly is a safety matter. Keep people clear and call local authorities and a professional.
Does subsidence stop on its own?
Sometimes, but not reliably. If the cause is regional, such as falling groundwater levels, movement can continue. The NRCS describes subsidence of organic soils as gradual, usually over several years 2. Only monitoring and a professional can say whether movement at your house has ended.
Does homeowner’s insurance cover subsidence?
It depends on the policy wording, exclusions, endorsements, cause and state law. Many policies exclude earth movement or soil-related damage. Do not assume coverage, and do not assume none. Read your policy and ask your insurer or state insurance department.
Who should check a house for subsidence?
A licensed structural engineer can assess the building. A geotechnical engineer can investigate the ground. HUD guidance on foundation repair says a structural engineer or a soils (geotechnical) engineer who specializes in this work should be consulted 5.
Should I try to fix subsidence myself?
No. Do not dig beside the foundation, jack the house or remove load-bearing parts. Homeowner steps that are safe include photographing and dating cracks, clearing gutters, directing downspouts away from the wall and keeping a log. Repairs need a professional’s design.
Sources
- U.S. Geological Survey Circular 1182, Land Subsidence in the United States (Galloway, Jones and Ingebritsen), retrieved .
- USDA NRCS, Technical Guide Section II, Soils Information: engineering interpretations (definition of subsidence), retrieved .
- Texas Department of Licensing and Regulation, IHB Technical Bulletin 10-01, Foundations on Expansive Soils – Residential (rev. Oct. 16, 2018), retrieved .
- Federal Highway Administration, Ground Modification Methods Reference Manual Volume I (FHWA-NHI-16-027, GEC 013), 2017, retrieved .
- U.S. Department of Housing and Urban Development, The Rehab Guide, Volume I: Foundations (prepared by Steven Winter Associates), retrieved .
Expert review
Written by the HyreFoundation Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Facts were checked against the federal, state and agency sources listed, each loaded on 2026-10-14. USGS Circular 1182 does not discuss damage to buildings, so no building-level claim is attributed to it. This page has not been reviewed by a named licensed engineer.
Suggest a correction. We fix errors and say what changed.