The short answer
Look for patterns, not single cracks. The ASCE Geo-Institute’s homeowner guide says the chance a foundation has moved rises with the number of signs you see, how often they show up, and where they are in the house. A diagonal crack over a bedroom door, a back door that won’t latch and a floor that slopes toward the same corner point the same way. A lone hairline crack in the garage doesn’t.
The Houston-based Foundation Performance Association adds the other half: not all distress is foundation movement. Its paper on lookalikes was written from the experience of engineers in southeast Texas, but the clay-country causes it lists apply in Collin County too.
Signs, what they can mean, and what else causes them
| Sign | Where to look | What it can mean | Could be something else |
|---|---|---|---|
| doors that bind or don't latch | Interior doors, especially toward the middle of the house | The door frame has racked as the slab bent | If the door frees up when you lift the knob, FPA points to a loose or undersized hinge. If it only won’t latch, often a strike plate out of alignment |
| cracks above doors or windows | Drywall at the top corners of openings | Movement concentrating stress at the weakest point of the wall | In a newly built house, wood framing drying out. FPA suggests waiting approximately two years for that shrinkage to settle before repairing |
| diagonal (stair-stepping) cracks in brick | Exterior brick near corners and below windows | One part of the foundation dropping relative to another | A straight vertical crack of even width from top to bottom is usually thermal expansion and contraction of the brick. Cracks above a wide garage door often trace to an undersized or overloaded lintel |
| sloping floors | Hard floors; a marble or a long level shows it | Tilt or a low area in the foundation | A slab that was built out of level, if nothing else in the house shows distress |
| Concrete floor cracks 1/16 inches or wider | Garage floor, under carpet or vinyl | The slab bending over high or low soil | Thin curing cracks. In post-tensioned slabs, FPA says no repair is usually required |
| frieze board separations | The trim board where the wall meets the eaves | The wall dropping away from the roof framing | Wood shrinkage, or roof framing pushing the top of the wall |
| walls separating from ceilings or floors | Interior wall corners, baseboards | Differential movement inside the house | Roof loads bowing a wall outward; FPA lists missing collar ties as one cause |
| Cracked floor tile | Kitchens, baths, entries | Slab movement, when the cracks run across several tiles in a line | flaws in the tile itself, when the cracks stay inside single tiles and the grout is intact |
| racked door and window frames | Windows that won’t lock, doors out of square | Frames pulled out of shape by movement | Poor original installation |
The first four columns come from what the Texas Real Estate Commission, ASCE Texas and the ASCE Geo-Institute tell inspectors and homeowners to look for. The last column is the Foundation Performance Association’s list of phenomena “often mistakenly attributed” to foundation movement.
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A room-by-room checklist
Inside
- Open and close every interior door. Note any that rub at the top corner, swing on their own or won’t latch.
- Look at the corners above doors and windows for cracks running at an angle.
- Check where walls meet the ceiling and the floor for gaps or separated tape.
- Roll a marble on hard floors, or lay a long level, in each main room.
- Look for cracked tile, and whether the cracks line up across tiles.
Outside
- Walk the brick at each corner and under windows for stair-step cracks.
- Look up at the frieze board and the corners of the trim.
- Check for gaps between window frames and the brick.
- Look where the driveway, patio and sidewalks meet the house. Gaps opening there are on the Geo-Institute’s list of exterior signs.
Around and under
- In a dry spell, look for soil pulling away from the slab edge. Houston black clay, the county’s main soil, has high shrink-swell potential and opens wide cracks when dry.
- Find where each downspout empties, and whether water stands near the house after rain.
- Compare water bills month to month. An unexplained jump can mean a leak under the slab.
Don’t dig beside the foundation to look underneath, and have utility lines marked before anyone digs near them.
Why cracks open in summer and close after rain
Collin County clay swells when wet and shrinks when dry. The Texas Department of Licensing and Regulation sums it up as heave when wet, settle when dry. The City of Richardson put it the same way in 2026: dry-to-wet soil fluctuation causes foundation issues over time.
That’s why timing tells you something. The 2026 dry streak at DFW ran 67 days without measurable rain, and cracks that open in a stretch like that and close by winter are the soil cycling. Cracks that keep growing through wet and dry seasons point to movement the soil isn’t undoing on its own. The best time of year guide covers what seasons mean for an inspection.
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Track it yourself before you call
A few weeks of records make any inspection more useful:
- Mark the ends of each crack with a pencil line and the date.
- Photograph each crack with a coin or tape measure beside it, from the same spot each time.
- Keep a door list: which ones stick, which won’t latch, and when it started.
- Re-check monthly, and after a long dry spell or heavy rain.
- Note the house’s year and type if you know them: slab or pier and beam.
If the cracks grow, or new signs join the old ones, that’s the pattern worth an inspection.
Contractor or engineer first?
| Call a foundation contractor first if | Call an independent engineer first if |
|---|---|
| You see several signs together and want to know what a repair would cost | You’re buying the house and want an opinion from someone with no stake in a repair |
| Cracks are growing and doors are getting worse | Two contractors’ plans disagree badly |
| You already expect a repair and want a written plan | An insurance claim or a past repair is in dispute |
A contractor’s visit gives you a plan and a price; the inspection page explains what it includes and how it differs from an engineer’s report. If the signs point to a slab that has moved, the slab repair page explains the fixes, and the cost page shows what they typically run.
Call to schedule an inspection, or send a request. A local foundation contractor who serves your area confirms a time and looks at the house with you.