A crack in your foundation, wall, or slab is unsettling to find — but it isn't automatically an emergency. Texas clay soil shifts seasonally, and small, stable cracks are common in homes of every age. The real question isn't "is there a crack," it's "is this crack telling me something is actively moving."
This guide walks through how to tell cosmetic cracks from structural ones, what repair actually involves, and when to stop monitoring and start calling someone.
Cosmetic vs. structural: how to tell the difference
Most cracks fall clearly into one category once you know what to look for. Here's the quick comparison:
Low concern
- Hairline width, under 1/16 inch
- Vertical, straight crack in drywall
- Not growing over weeks/months
- No accompanying door/window sticking
Higher concern
- Wider than 1/4 inch, or growing
- Diagonal or stair-step pattern
- Visible in the foundation/slab itself
- Paired with sticking doors or sloping floors
Diagonal cracks are a particularly useful early signal — they typically radiate from a corner of a window or door frame at roughly 45 degrees, which is the pattern foundations make as they settle unevenly underneath the structure above.
If a crack is wide enough to fit a credit card edge into, growing month over month, or showing up alongside doors that no longer close right, that's no longer a "monitor it" situation — get it looked at.
How crack injection repair actually works
For cracks that don't indicate ongoing structural movement, injection repair is the standard fix — it's faster, less invasive, and significantly cheaper than pier-based foundation work.
Epoxy injection
Epoxy is used on cracks that are structurally stable but need to be sealed and strengthened. It's rigid once cured, which actually bonds the two sides of the crack back together — appropriate when the crack isn't expected to keep moving.
Polyurethane injection
Polyurethane stays flexible after curing, which makes it the better choice for cracks that may experience minor ongoing movement, or where water intrusion is the primary concern rather than structural bonding. It expands to fill voids and is commonly used for cracks that leak during heavy rain.
This depends on whether the crack is actively leaking, how wide it is, and whether it's still moving. That's exactly what a proper inspection is for — not something to guess at from a tube at the hardware store.
What crack repair costs in Austin
| Repair type | Typical cost range |
|---|---|
| Single hairline crack, epoxy injection | $300 – $700 |
| Multiple cracks, epoxy injection | $700 – $1,800 |
| Polyurethane injection (leak-focused) | $400 – $1,200 |
| Crack found to be structural (requires piers) | See slab or pier & beam repair pricing |
If an inspection finds the crack is a symptom of ongoing foundation movement rather than an isolated, stable crack, the recommendation shifts to pier-based repair — covered in our slab foundation repair guide.
Can I fix a foundation crack myself?
DIY crack-filler kits exist, and for genuinely cosmetic, non-moving hairline cracks, they're not unreasonable. The risk is misdiagnosis — sealing over a crack that's actually an early sign of structural movement just hides the symptom while the underlying cause keeps going. A free inspection costs you nothing and removes the guesswork before you decide.
Not sure which kind of crack you have?
Get a free inspection and a written diagnosis — no pressure, no obligation.
How long does crack repair take?
Most injection repairs are completed in a single visit, often in under two hours per crack. There's no curing downtime that keeps you out of the house — epoxy and polyurethane both cure fully within 24 hours.