01Reading a crack
Thin, hairline shrinkage cracks that stay the same width are typical in slabs, driveways and patios. Cracks wider than about a quarter inch, cracks where one side sits higher than the other, and cracks that keep growing season after season suggest the ground is moving.
A simple way to track a crack is to mark its ends with a pencil and date, and measure its width every few months. Photos taken from the same spot also help a contractor judge whether it is active.
02Repair approaches
Structural cracks in foundation walls or beams can be injected with epoxy to bond the concrete back together. Polyurethane injection flexes and is often used to stop water seeping through cracks. Flatwork such as driveways and sidewalks is usually routed and filled with a flexible sealant to keep water out of the subgrade.
Sunken sidewalks and patio sections are sometimes lifted with polyurethane foam or slurry injection rather than being torn out. Ask whether lifting is realistic for your slab and how long the repair is expected to last.
03When cracks mean more
If cracks in the slab line up with sticking doors or brick cracks, the issue is probably foundation movement, not just concrete. In that case look at commercial foundation repair for business properties or slab work for homes, and treat the crack repair as a finishing step.
04Types of cracks
Shrinkage cracks are thin and common. Cracks with one side higher, cracks that widen, or diagonal cracks from corners deserve attention. Garage slabs and driveways crack often without involving the house foundation.
Epoxy or polyurethane injection seals some cracks; it does not lift a sinking foundation.
Crack types
Reading a crack before you seal it
| Crack | Usually means | Typical response |
|---|---|---|
| Hairline, vertical | Normal shrinkage | Seal and watch |
| Stair-step in brick | Movement under a corner | Inspection first |
| Wider at one end | One side is sinking | Elevation check, then repair |
| Horizontal in a wall | Pressure from soil | Structural review |
Around Tyler
How this looks in East Texas homes
- Hairline cracks in a garage slab
- Thin shrinkage cracks are common in East Texas slabs and are often cosmetic. Sealing keeps water and insects out.
- A crack that keeps widening
- A crack that grows or shows one side higher than the other suggests movement; an elevation survey should come before patching.
- Cracks in a driveway
- Tree roots and clay movement crack driveways; sealing or replacing sections is common.
Avoid these
Common mistakes
Patching before finding the cause. A patch over a moving crack will crack again.
Using rigid filler on a moving crack. Flexible sealant handles seasonal movement better.
Before you hire
Questions to ask
- Is this crack structural? Ask how they decide.
- What material will you use? Epoxy or polyurethane, and why.
- Will you measure elevation? A survey shows whether the slab is moving.
Step by step
How the job usually goes
- 1
Look at the pattern
The tech notes crack width, length and whether one side is higher, and checks nearby doors and floors for movement.
- 2
Measure
Elevation readings tell cosmetic cracks apart from cracks caused by movement.
- 3
Clean and seal
Cosmetic cracks are cleaned and filled with epoxy or flexible polyurethane, depending on whether movement is expected.
- 4
Check drainage
Water running to the crack is redirected so it doesn't keep soaking the soil.
- 5
Follow-up
Mark the crack ends with a pencil and date, and check them after a few months to see whether the crack has grown.
Photos
