Foundation Repair · Service

Foundation cracks: document first, buy later

A crack is evidence that something happened. It is not evidence of what is happening now. The cheapest useful thing you can do this week costs nothing and takes ten minutes.

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In short

What is foundation crack repair?

Foundation crack repair covers two different objectives that are often sold as one: sealing a crack so water stops coming through it, and addressing whatever movement produced it. Sealing is a legitimate, comparatively inexpensive job. Movement is a structural question that a sealant does not answer. The honest first step for most homeowners is neither — it is to document the crack properly and find out whether anything is still moving.

The job

How foundation crack repair actually works

Photograph and date it before you do anything

Shoot from a repeatable position with something of known size in the frame. Mark each end with a pencil line and write the date on the wall beside it. This takes minutes and creates the only record anyone will ever have of what the crack looked like before it was touched.

Watch for: Doing this after a contractor has already patched or ground the surface. Preparation destroys the evidence, and the pre-repair condition is what any later assessment or claim needs.
Monitor over time rather than judging on one look

A crack monitor fixed across the crack, or repeated photographs against your pencil marks, tells you over months what one inspection cannot tell you in an hour: whether the movement is finished.

Watch for: A monitoring period with no end date. Set the review point when you start, or it becomes doing nothing indefinitely.
Look outside at the same wall

Most water-related cracking has a visible external cause: a downspout emptying at the foundation, ground sloping back toward the house, a blocked gutter, a bed mounded up against the wall. All cheap to correct and worth correcting anyway.

Watch for: Sealing the inside face while the outside keeps delivering water to the same spot. The seal gets tested by the conditions that made the crack a problem in the first place.
Separate the water objective from the movement objective

If the goal is to stop water coming through, that is a sealing job. If the goal is to address why the crack formed, no product injected into the crack does that.

Watch for: A quote that presents sealing as a structural repair. The two get bundled because the second is much easier to sell once you are worried.
Understand what each injection material is for

Epoxy is rigid and bonds the two faces, so it is used where the intent is to restore continuity across a crack in sound concrete that is not moving. Polyurethane is flexible and expands, so it is used to stop water passing through, including in damp conditions. Neither addresses soil movement.

Watch for: A rigid material used on a crack that is still moving. Bonding a joint that is still being worked relocates the next crack alongside the repair.
Prepare properly, because preparation is the whole job

Surface preparation, port placement along the crack, sealing the face so material stays inside, and injecting at a controlled rate from one end to the other is what makes an injection reach the full depth rather than sit in the first inch.

Watch for: A fast surface smear presented as injection. It looks finished and it is a cosmetic repair, which you will discover during the next sustained rain.
Decide about the cause, separately and unhurriedly

With a monitoring record in hand, an independent assessment can say whether anything further is warranted — and is equally free to say that nothing is.

Watch for: Making the structural decision on the day the crack is sealed, alongside the person holding the caulk gun. Both decisions rarely have to happen in the same week.

Money

What does foundation crack repair cost?

Documenting and monitoring a crack costs close to nothing. Professional injection of a single crack is typically a modest job at the low end of foundation work. Structural investigation and any underpinning that follows are in an entirely different order of magnitude, which is why the sequence matters.

See the full foundation crack repair cost guide — by material, size and region →

Straight answer

When foundation crack repair is the wrong call

Everyone else ranking for this is paid when you say yes. Here's when you shouldn't.

You have not established whether the crack is still moving. Sealing an active crack is repairing something that is still happening. A short documented monitoring period costs almost nothing and changes what you should buy.
You are being sold underpinning on the strength of a crack alone. A support scheme should trace to an elevation survey, not to a photograph of a wall.
The crack is in the floor surface rather than the structure. Slabs shrink and craze as they cure. That is a surface question, not a foundation one.
The crack is horizontal in a basement wall. That pattern belongs to the lateral-pressure conversation, and sealing it treats the leak while leaving the loading unaddressed.
Your objective is a dry basement generally, not this one crack. If water comes in at several points, or through the floor-wall joint, you are in basement waterproofing territory and a single injection will disappoint you.
You are about to sell and want it out of sight. A freshly patched crack in an otherwise unremarkable basement reads to buyers and inspectors as something concealed. A documented monitoring record reads considerably better.

Your options

Types of foundation crack repair

Document and monitor

The cheapest and most informative first step, and the one nobody sells you.

Polyurethane injection

Flexible, expanding, aimed at stopping water passing through.

Epoxy injection

Rigid and bonding, used on sound concrete where movement is not ongoing.

Independent assessment of the cause

Someone with no product to inject telling you whether anything further is warranted.

Documented crack patterns

What various patterns tend to indicate, described without a proposal attached.

Compare foundation repair options side by side →

Straight answer

Can I do this myself?

One thing is worth stating before anything else: no article, photograph or width measurement can tell you whether a particular crack in your house is structurally significant. Anyone — including a website — who says otherwise without measuring your building is guessing. What follows is about documenting and sealing, not diagnosing.

Reasonable to DIY

Documenting the crack: dated photographs from a fixed position, with a ruler or a coin in frame for scale, repeated on a schedule
Marking the ends of the crack with a pencil line and the date, so any extension becomes obvious rather than remembered
Fitting a simple crack monitor across the crack and reading it periodically — an inexpensive item that turns an argument into a record
Checking the outside of that wall: where downspouts discharge, whether the ground slopes toward the house, whether the gutters work
Extending downspouts and correcting obvious ponding against the foundation, which helps regardless of what the crack turns out to be
Sealing a non-moving crack in a non-structural application — a garage slab surface, a step, a path

Call a licensed pro

Injection of a crack in a foundation wall or slab, where the preparation, the port spacing and the injection pressure decide whether the repair holds
Any crack where the two faces have moved out of plane, or where the opening is not consistent along its length
Cracking that arrived alongside other symptoms — sticking doors, a changed floor, cracking in more than one room, or that measurably changed while you monitored it
Any crack in a post-tension slab, where drilling near unknown tendon positions is genuinely dangerous
Deciding whether the underlying movement needs addressing at all — an independent engineer's question, not a sealant vendor's
Horizontal cracking in a basement wall, which is a lateral-pressure question covered at bowing wall repair

Before you sign

What to check when hiring for foundation crack repair

Are you quoting me a water repair or a structural repair?

The question that prevents the most common mistake in this whole category. Make the answer explicit and make it appear on the quote.
Which material are you using, and why that one for this crack?

A reasoned answer references whether water is passing through and whether movement has been established. An answer that references only what is on the van does not.
Have you established whether this crack is currently moving, and how?

If nobody has monitored it, nobody knows — and both of you should be honest about that before choosing a rigid material.
How will you inject it, and how do you know it filled the full depth?

Distinguishes injection from a surface fill. Ask about port spacing, face sealing and how completion is judged.
Is my slab or wall post-tensioned, and have you checked before drilling anything?

Drilling near unknown tendon positions is the one genuinely hazardous mistake available in this otherwise low-risk job.
What outside conditions do you think contributed, and what would you do about them?

A contractor who looks at your downspouts before your basement wall is thinking about the cause. One who never goes outside is selling a product.
What exactly does your warranty on this crack cover?

These often cover water passing through that specific repaired crack and nothing else — not a new crack beside it, not the wall, not the finishes. Ask whether the warranty is yours or the manufacturer's.

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Local pros

Foundation Crack Repair near you

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Related work

Often done at the same time

Foundation Inspection

Getting an opinion from someone with nothing to sell

Bowing Wall Repair

Where horizontal cracking belongs

Slab Foundation Repair

Cracking in a slab-on-grade house

Basement Waterproofing

When water is coming in at more than one place

All foundation repair services →

FAQ

Foundation Crack Repair — questions people ask

Still have a question? Talk to our team →

Is my foundation crack serious?

Nobody can answer that from a description or a photograph, and you should be sceptical of anyone who tries — including us. What can be said is what warrants a professional look: a crack that has changed during a period of monitoring, one that is wider at one end than the other, one where the faces have moved out of plane, or one that arrived alongside doors sticking and floors changing. Document yours, then get an opinion from someone with nothing to sell.

Should I use a DIY injection kit from a hardware store or Amazon?

For a non-structural application that is not moving — a garage floor, a step, a path — sealing it yourself is reasonable and the products work. For a foundation wall or slab, the material is rarely the limiting factor: preparation, port spacing and controlled injection decide whether it fills the full depth. And a kit answers the sealing question while leaving the movement question untouched.

What is the difference between epoxy and polyurethane injection?

Epoxy cures rigid and bonds strongly, so it is chosen where the aim is to restore continuity across a crack in sound concrete that is not moving. Polyurethane is flexible and expands as it reacts, so it is chosen where the aim is to block water, and it tolerates damp conditions better. Neither is stronger in a useful sense for your decision, and neither resists soil movement — treat any claim otherwise carefully.

How long should I monitor a crack before deciding?

Long enough to cross the conditions that would make it move — in most climates a wet period and a dry one, not a couple of weeks. Mark the ends or fit a monitor, take readings on a schedule you will actually keep, and set the review date at the start.

Will sealing a crack stop my foundation moving?

No. Injection fills a void in concrete. It does not change what the soil beneath or behind the foundation is doing, it adds no support, and it does not reduce lateral pressure. If ongoing movement produced the crack, sealing addresses the water and leaves the cause where it was.

A contractor gave me a free inspection and quoted piers because of one crack. Is that normal?

It is common, which is not the same as being right. The visit is free because it is a sales channel, and a crack is the most reliable thing in a house to build a proposal around. That does not make the diagnosis wrong — it makes it unverified. Ask what measurements support the pier count.