Finding a crack in your foundation is scary, especially at 11 at night with a flashlight. Most of them don't deserve that much worry. A few really do, and telling the difference is what matters.
Good foundation crack repair has two parts: seal the crack, then figure out why it showed up. We measure first, because sealing a crack on a moving wall is money you'll spend twice.
The short answer
Foundation crack repair seals a crack with epoxy or polyurethane injection and stops whatever caused it. Hairline cracks under 1/16 inch usually just need watching. Cracks wider than 1/4 inch, horizontal cracks and cracks with one side higher need a professional look, since the wall may be moving.
Which cracks need foundation crack repair (and which don't)
Width, direction and offset tell you whether a crack needs repair. Here's the chart we use when we're standing at the wall with a gauge. If you want more detail and pictures, our guide on which foundation cracks are normal goes through each one.
| The crack | What we'd do |
|---|---|
| Hairline, vertical, under 1/16 inch | Monitor it. It's usually concrete shrinkage. |
| Vertical, 1/16 to 1/4 inch | Seal it, especially if it leaks. |
| Wider than 1/4 inch | Call us. It could be movement. |
| Horizontal | Call us now. Soil may be pushing the wall in. |
| Stair-step in block or brick | Call us. One part of the house may be settling. |
| One side higher than the other | Call us now. That's movement, not shrinkage. |
How we fix foundation cracks
We match the repair to the crack. Injection takes care of the crack itself, and reinforcement or piers deal with whatever caused it.
Epoxy injection for structural cracks
Epoxy bonds concrete back together and can end up stronger than the wall around it. We use it on stable cracks, usually vertical ones that aren't actively leaking. If the wall's still moving, epoxy won't help, since a new crack will just form beside it.
Polyurethane injection for leaking cracks
Polyurethane expands as it cures, so it chases water through the full thickness of the wall and stays flexible afterward. It's our first choice for sealing foundation cracks that leak after rain. It doesn't add strength, and we'll tell you that up front.
Carbon fiber straps or wall anchors when the wall is moving
If a wall is starting to bow, carbon fiber straps bond to the concrete and hold it in place. Wall anchors do the same job for walls that have moved further, tying them to plates buried in the yard.
Piers when the crack comes from settling
Stair-step cracks and offset cracks often mean part of the house is sinking. No resin will stop that. You've got to support the foundation on deeper soil, which is what our foundation piers are for.
- We measure the crack and photograph it.
- Injection ports go along the crack.
- Resin goes in at the bottom port and works its way up.
- Ports come off and the surface is sealed.
Horizontal foundation crack repair
Horizontal foundation crack repair starts with the wall, not the crack. A horizontal crack usually means the soil outside is pushing the wall inward, so sealing it alone would hide the warning sign.
We measure how far the wall has bowed, usually with a plumb line. Then we anchor or reinforce it, and only after that do we seal the crack. If you're seeing this, read about why basement walls lean in, because the same forces are at work.
Our foundation wall crack repair process
Our foundation wall crack repair process takes five steps, and most jobs are done in a day. Concrete foundation crack repair isn't complicated work, but preparation decides if it holds.
- Measure and photograph. We record the width and length, then check whether the wall has moved.
- Clean. Loose material, paint and old patches come off so the sealant can bond.
- Install ports. Small ports go along the crack, and the surface gets sealed over.
- Inject. Resin goes in at the lowest port and moves up until it comes out the next one.
- Verify. After it cures, we pull the ports and record the final measurement for you.
Fixing foundation cracks in winter works fine indoors, but the wall has to be above the resin's minimum temperature. We'll check that before we start.
How to repair a cracked foundation yourself (and when not to)
You can repair a cracked foundation yourself if the crack is thin, dry and not moving. Hardware stores sell injection kits and sealants that do a fair job on those. Fill and seal it, then keep an eye on it with the date marked.
Don't try to fix foundation crack problems yourself if the crack is wider than 1/4 inch, runs horizontally, has water pushing through or sits with one side higher. Those aren't patch jobs. Cracked foundation repair at that stage has to deal with the wall, and a tube of sealant from the store only hides the evidence.
What it usually runs
Crack injection usually runs $250–$800 per crack. Reinforcing a moving wall runs $4,000–$12,000. Those are typical ranges, and your exact price depends on what we find at the inspection. Here's more on what most repairs actually run.
Length and access move the number most. A 4-foot crack behind a finished wall takes more work than an 8-foot crack in an open basement. A free inspection gets you a written number for your wall.
Foundation crack repair questions
How long does crack injection last?
A good injection on a stable crack usually lasts as long as the wall. The resin itself rarely fails. What fails is a repair on a wall that's still moving, because the movement opens a new crack beside the old one. That's why we check for movement first.
Will the crack come back after repair?
Not if the wall has stopped moving. If soil or water keeps pushing, a sealed crack can reopen or a new one can appear nearby. We'll measure the crack and the wall, then tell you if sealing is enough or if the cause needs fixing too.
How can I tell if a crack is still moving?
Mark both ends with a pencil, write the date and measure the width. Check it every month for six months. If it gets longer or wider, it's moving. A crack monitor from a hardware store costs little and reads smaller changes than a tape measure can.
Are foundation cracks covered by insurance?
Usually not. Most homeowners policies exclude settling and normal wear. There can be exceptions when a covered event, like a burst pipe, caused the damage. Read your policy or call your agent, and take dated photos before anything gets repaired so you've got a record.
Do I need an engineer for a cracked foundation?
Not for most cracks. You'll want one for major movement, a home sale dispute or when your city asks for stamped plans. Start with a free foundation inspection, and we'll tell you honestly if your situation calls for an engineer's report.
How do you repair foundation cracks?
We clean the crack, set ports along it and seal the surface, then inject resin from the bottom up. Epoxy bonds stable structural cracks and polyurethane stops leaks. If the wall is moving, we add carbon fiber, anchors or piers first, so the repair holds.
Is epoxy or polyurethane better for foundation cracks?
It depends on the crack. Epoxy is stronger and bonds the concrete back together, so it suits dry, stable structural cracks. Polyurethane stays flexible and foams to fill gaps, so it suits leaking cracks. Neither one will hold back a wall that's still moving.
Can a foundation crack be repaired from the inside?
Yes, and that's how most are done. Injection pushes resin through the full thickness of the wall from the inside, so nobody has to dig up your yard. Exterior work only makes sense for a few cases, like a badly crumbling wall or membrane repairs.
Run into a term you don't know? This may help: foundation repair glossary.