Bring your dated readings and photographs to any inspection — they shorten the conversation considerably
Homeowner guide · 15 minutes, then a few minutes each season
How to tell whether a foundation crack is actually moving.
Almost every foundation has a crack. What matters is whether it is changing, and memory is a poor instrument for that.
Safety first
Monitoring is for tracking a condition over time, not for deciding whether a wall is safe. A wall that is bowed, displaced or visibly changing needs assessment now rather than observation.
Before you start
What you need.
- A pencil
- A crack gauge, calipers or a steel rule with fine graduations
- A camera or phone
- A notebook or a note on your phone
Step by step
8 steps.
- 01
Clean the surface. Brush away dust and loose material around the crack so your marks sit on sound masonry and stay legible for months.
- 02
Mark each end. Draw a short pencil line across the crack at each end and write the date beside it. If the crack later extends past your mark, that is unambiguous evidence of growth.
- 03
Establish a measuring point. Choose one spot along the crack, ideally the widest, and mark a line on each side perpendicular to it. Always measure at this same point, otherwise you are comparing different places rather than different times.
- 04
Record the width. Measure the gap at your marked point with a crack gauge or calipers and write it down with the date. A gauge taped over the crack gives the easiest repeatable reading.
- 05
Photograph with a scale. Take a photograph with a ruler or tape measure in frame beside the crack, and a second wider shot showing where on the wall it sits. Photographs without a scale are much harder to compare later.
- 06
Note the conditions. Record the date, the season and anything relevant: recent heavy rain, a spring thaw, a very dry spell. Some cracks open and close seasonally, and that pattern is itself informative.
- 07
Repeat each season. Take a new reading roughly every three months, and after any unusually wet period. Keep every reading rather than only the latest, because the trend is the finding.
- 08
Watch for the signals that change the answer. If the crack widens measurably, extends past your end marks, develops displacement so one side sits proud of the other, or starts passing water, stop monitoring and get it evaluated.
After the check
What to do with the result.
A stable, dry crack with no displacement across a year is a very different finding from a growing one
Horizontal cracks and bowing walls are not candidates for watchful waiting
Keep the record even after a repair, so you can tell whether the repair held
Common questions
How to Monitor a Foundation Crack
How much crack movement is too much?
There is no single number that applies to every wall, because it depends on the material, the pattern and whether displacement is developing. What is clear is that measurable growth over a year, extension past your marks, or one side moving out of plane relative to the other are all reasons to have it evaluated rather than to keep watching.
Is it normal for a crack to open and close with the seasons?
Some seasonal movement is common as soil moisture and temperature change through the year. That pattern, returning to roughly the same width each cycle, is different from a crack that grows and stays grown. Keeping readings across a full year is what lets you tell them apart.
Should I fill the crack while monitoring it?
Filling it removes your ability to measure and can hide continuing movement. If water is coming through and needs addressing sooner, note that the repair also ends the monitoring, and ask the contractor to record the width and pattern before sealing it.
Request local service
Want someone to look at what you found?
Describe the result and we will inspect the property.