Quick answer
Foundation movement monitoring is the practice of measuring a house at set intervals, with crack gauges, floor-level readings or survey targets, to learn whether the structure is moving, in which direction, and whether the movement is changing.
One look at a crack shows where it is. Repeat measurements show whether it is active. That difference, active or not, is what monitoring is for.
Quick facts
The key facts about Foundation Movement Monitoring, with sources:
- Simple tool
- Two-plate crack gauge fixed across a crack; a crosshair reads against a graduated scale 1
- Bigger tool
- Survey targets read by a total station and compared with benchmarks 1
- Homeowner record
- Dated photos from the same spot, plus floor elevation notes 3
- Reads
- Direction and amount of movement over time, not a verdict 1
- Seasons matter
- Seasonal movement opens and closes some cracks regularly 4
- Who interprets
- A licensed structural engineer, with soil and water information 3
Key takeaways
- A crack seen once is a snapshot. A crack measured over months is a trend.
- The National Park Service advises watching cracks over time to see whether they are active, because the answer changes how they are repaired 2.
- Seasonal movement can open and close some cracks every year, so a short record can mislead 4.
- A crack monitor records movement. It does not say why the movement happens or what to do about it.
- Share dated readings with a licensed structural engineer. The readings are most useful in their hands.
What monitoring is, and what it is not
Monitoring means taking the same measurement the same way at regular times.
The measurement may be the width and slip of a crack, the height of floors against a fixed reference, or the position of survey points on a wall. The point is repetition.
Two readings tell you little. A series tells you the direction and rhythm of movement.
STRUCTURE magazine describes the basic gauge. It uses two plates fixed on either side of a separation, one with a clear crosshair and the other with graduations.
If the sides shift, the crosshair moves against the scale 1. Larger projects add optical targets read by a total station and compared with benchmark locations in three directions 1.
Monitoring is not a diagnosis. It cannot name a cause. It supplies evidence to someone who can. For the wider picture, see settlement vs. heave.
General information, not a diagnosis of your house
General information, not a diagnosis of your house. A reading on a gauge does not tell you whether a crack is safe or unsafe. A licensed professional who sees the building can.
Types of monitoring: tools, what they show and who uses them
| Method | What it records | Who typically uses it |
|---|---|---|
| Dated photographs from a fixed spot | Visible change in a crack or gap over time | Homeowners 3 |
| Two-plate crack gauge | Movement across one crack, read against a scale 1 | Homeowners and engineers |
| Elevation readings of floors | High and low points of the floor, repeated | Engineers; homeowners can keep a log |
| Optical survey targets | Position of targets on a wall, read from a fixed station and compared with benchmarks 1 | Engineers and surveyors on larger jobs |
| Vibration monitors | Vibration at a building during nearby work 1 | Engineers on construction projects |
Four wall sketches showing a horizontal crack, a vertical crack, a diagonal crack and a stair-step crack in block, each with a short note on what the pattern can be consistent with.
Illustrative, not to scale, not a design. It shows horizontal, vertical, diagonal and stair-step sketches. A pattern is a clue, not a diagnosis.
How a crack gauge works, step by step
- Two plates are fixed on either side of the crack so they overlap 1.
- One plate carries a scale of graduations. The other is clear and carries a crosshair 1.
- A starting reading is taken and written down with the date.
- If the two sides shift, the crosshair moves against the scale. Its ends show the movement 1.
- Later readings are compared with the first and with each other.
- The record goes to an engineer, who judges what it means with soil and site facts.
Follow the maker’s instructions when fixing any gauge. Product instructions differ by type and surface.
Example: what a simple monitoring log looks like
The monitoring log below is a format example, not a real house. The entries are blank on purpose: no measurement shown here is a norm or a limit.
| Date | Reading (units you choose) | Weather and water notes | Photo taken |
|---|---|---|---|
| Day 1 | Starting reading | Dry week, gutters clear | Yes |
| Month 1 | Reading | Heavy rain recently | Yes |
| Month 3 | Reading | Dry spell | Yes |
| Month 6 | Reading | Wet season | Yes |
| Month 12 | Reading | Back to the same season as day 1 | Yes |
Comparing month 12 with day 1 shows a year’s net change. Comparing the months in between shows whether the crack follows the seasons. Bring the full table to the engineer.
Where monitoring is placed
Gauges go on cracks that you or a professional want to track. These are often cracks near door and window corners, where walls meet, or along a foundation wall.
Choose a spot you can reach safely, and avoid places where people or pets will bump the gauge. STRUCTURE magazine notes that optical targets are kept out of pedestrians’ reach for this reason 1.
Floor-level readings go where the floor changes height. Pick fixed points such as door thresholds and write down where each reading was taken. An elevation log gives a structure for the record.
Do not fix gauges inside crawl spaces with standing water, gas or electrical hazards, and do not climb ladders to reach high cracks. Ask a professional for those.
Why monitoring is worth doing
What a record gives you
- It separates cracks that are changing from ones that are not 2.
- It gives an engineer a time series instead of a single look.
- It may reveal a seasonal rhythm that points to soil moisture.
- It is a record for a seller, buyer, insurer or second opinion. See foundation repair documentation.
What it will not give you
- It does not state a cause.
- It does not say whether a crack is safe.
- It can be thrown off by a loose gauge, a bumped plate or inconsistent reading habits.
Limits of monitoring
- A short record can mislead. Seasonal movement opens and closes some cracks regularly 4.
- A gauge measures one crack in one place. A house can move elsewhere.
- A gauge shows relative movement across the crack, not whether the whole house is rising or sinking. That needs elevation readings.
- No reading is a universal “safe” or “unsafe” number. None is given here and none should be invented.
- Monitoring cannot protect a house on its own. It only informs decisions.
What drives the cost of monitoring
We print no prices. A homeowner’s basic record needs a camera, a notebook and, if wanted, a gauge. The cost drivers for professional monitoring are the number of points, the length of the program, the tools used, how often readings are taken, and who takes them.
STRUCTURE magazine notes that the reading frequency is increased if a monitored structure is particularly vulnerable or if movement trends appear 1. More frequent readings cost more.
For cost factors tied to your inputs, see the cost guide.
How to start a monitoring record at home
- Pick the cracks. Choose the ones that worry you most, and number them.
- Photograph each one. Include a ruler or coin for scale, the date, and the same framing every time 3.
- Mark the spot you stood. Use tape on the floor or a note so the angle repeats.
- Add a gauge if you want a number. Fix it as the maker directs and write down the starting reading.
- Read on a schedule. Pick a day each month and add notes on weather, irrigation and leaks.
- Keep a floor log. Use the elevation log tool for heights at fixed points.
- Share the record with an engineer or inspector. Use the inspection checklist for what else to note.
Do not paint, caulk or patch over a crack you are monitoring
Filling or covering a crack hides the very change you want to see. Take the reading first and ask a professional before sealing.
Keeping the record useful
- Read at the same time of day and in the same conditions where you can.
- Replace a gauge that has been knocked, and note the date and the change in the log.
- Keep a note of any event that could matter: a plumbing leak, a large storm, nearby digging, a new load, or a tree removed.
- Back up photos and keep them with the dates.
- Keep gutters and downspouts working and note what the weather was doing. See seasonal soil moisture changes.
Risks of monitoring badly, or instead of acting
The first risk is false comfort. A stable reading over a few dry weeks does not prove a crack is finished, because movement may track the seasons 4. The second is false alarm: a loose gauge can look like movement.
The bigger risk is delay. Monitoring is a way to gather information, not a reason to wait when signs point to trouble. HUD’s guide says repair should not be undertaken until the principal cause of cracking is determined, which calls for investigation, not for waiting 3.
Never assume a specific crack is harmless, and never assume every crack needs underpinning. Both claims need a professional’s view.
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 not wait for a full year of readings if any of these apply.
Standards, codes and monitoring
No residential code tells a homeowner how to monitor a crack. Monitoring on larger projects follows plans set by the engineer of record.
STRUCTURE magazine’s case study describes a monitoring program with limits set for a project, and says that when limits are exceeded the engineer of record and the building department are typically notified 1. Those limits are project-specific and are not guidance for a house.
For a home, the relevant rules are professional: ask your state licensing board about engineer licensing. Do not treat a gauge supplier’s printed scale as a safety standard.
Scope of the source
The STRUCTURE article describes monitoring around building rehabilitation in a dense city. Its limits and frequency are specific to that project and are not a rule for homes.
Monitoring compared with related steps
| Step | What it does | What it needs |
|---|---|---|
| Monitoring | Records movement over time | Repeat readings |
| Foundation inspection | A professional looks at the building at one point in time | A visit |
| Crack-identification tool | Helps you describe a crack in words | Photos and notes |
| Geotechnical investigation | Tests the soil | Borings and lab work |
Myths about monitoring
- Myth A crack that has not moved in a month is stable.
- Reality Seasonal movement can follow a longer rhythm 4.
- Myth A gauge tells you whether a crack is dangerous.
- Reality It reports movement only. Safety needs a professional’s judgement.
- Myth A sealed crack is a fixed crack.
- Reality Sealing hides movement. The National Park Service says active cracks need a flexible sealant, not a rigid fill 2.
- Myth Monitoring replaces an engineer.
- Reality It feeds an engineer’s work. It does not replace it.
- Myth More readings are always better.
- Reality Consistent readings on a schedule beat many careless ones.
Why climate shapes the reading schedule
In regions with swelling clay, cracks can follow wet and dry cycles.
Colorado SP-11 describes volume change from soil moisture, with damage from swell and from shrinkage in semi-arid cycles 5, and Virginia Energy notes hazards worsen after prolonged drought followed by saturating rain 6.
In cold regions, frost can add a winter pattern 6. A full year of readings is a sensible span in these places, because it covers each season.
When to monitor and when to call
Use the guide to match what you see with an action.
- If A small crack that has been there a while, no other signs
- Then Photograph, date and monitor through a full year
- If A crack that you notice changing, or a new one
- Then Keep readings and ask an inspector or engineer to look
- If Sticking doors with new cracks, or separation at corners
- Then Ask a licensed structural engineer
- If A wall that is displaced or bowing
- Then Call a licensed structural engineer promptly
Bring your record to the first visit
A dated log saves an engineer time. See the engineer-or-contractor tool to choose who to call first.
Questions about Foundation Movement Monitoring
What is foundation movement monitoring?
It is measuring a house at set times, with crack gauges, floor-level readings or survey targets, to see whether it is moving and how. Repeat readings show direction and trend. A single look shows only where a crack is today 12.
How does a crack monitor work?
A common type uses two plates fixed on either side of a crack. One has graduations, and the other is clear with a crosshair. If the crack sides shift, the crosshair moves against the scale 1. You write down the reading and compare it with later ones.
How long should I monitor a crack?
Long enough to cover the seasons. Seasonal movement opens and closes some cracks regularly 4, so a few weeks can mislead. A year is common in climates with wet and dry seasons. Call an engineer sooner if the crack changes quickly or other signs appear.
Can I monitor a crack with just a camera?
Yes, as a start. Photograph the crack with a coin or ruler for scale and the date, from the same spot each time. The record is less exact than a gauge but is easy to keep and useful to an engineer 3.
What does it mean if a monitored crack is moving?
It means the crack is active, and the cause deserves investigation. The National Park Service notes that active cracks need different treatment from inactive ones 2. The reading does not say why it moves. A licensed structural engineer can assess.
What if the crack does not change?
Then it may be stable over the period you watched, but that is not a promise. Movement can follow the seasons or return after a leak or storm 4. Keep reading through a full year and add notes about weather and water.
Should I seal a crack I am monitoring?
Read it first and ask a professional before sealing. Filling or painting over a crack hides what you want to see. The National Park Service says active cracks should be sealed with a flexible sealant, while inactive cracks may be pointed 2.
Is there a crack width that means danger?
No universal number applies to every house, and none is given here. Movement history, displacement, water, construction details and site conditions all affect how a crack is read. Treat widening or changing cracks, and any safety doubt, as reasons to ask an engineer.
Who should read my monitoring results?
A licensed structural engineer. HUD guidance says a structural engineer or a soils engineer who specializes in foundation work should be consulted when foundations settle 3. Bring your dated photos, readings and notes about weather and water.
Does monitoring help with insurance or a sale?
A dated record can support a conversation with an insurer, buyer or second-opinion engineer, but it does not guarantee any outcome. Coverage depends on policy wording, exclusions, cause and state law. Keep the record with your other house documents.
Sources
- STRUCTURE magazine, Monitoring the Health of a Building during and after Rehabilitation (Pilla, Vaccaro and Wilde, Dec. 2015), retrieved .
- National Park Service, Common Problems with Brick Masonry (updated June 29, 2018), retrieved .
- U.S. Department of Housing and Urban Development, The Rehab Guide, Volume I: Foundations (prepared by Steven Winter Associates), retrieved .
- HUD User, Residential Inspection (rehabilitation inspection guide), chapters 2 and 4 (file rehabinspect_2.pdf), retrieved .
- Colorado Geological Survey, Special Publication 11: Home Construction on Shrinking and Swelling Soils (Holtz and Hart for the American Society of Civil Engineers, 1978), retrieved .
- Virginia Energy, Geology and Mineral Resources: Expansive Soils, 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, agency and engineering-magazine sources loaded on 2026-10-14.
The STRUCTURE article concerns monitoring in a rehabilitation project, so only its description of gauges and survey methods is used. No crack-width threshold or price is given. This page has not been reviewed by a named licensed engineer.
Suggest a correction. We fix errors and say what changed.