Is a foundation crack serious? How to tell, and the cost
A vertical hairline crack is usually shrinkage. A horizontal crack or bowing wall means real damage. An engineer's visit runs $400 to $1,500.
Updated · By 
Ben Sikes
How do you know if a foundation crack is serious?
Look at the direction and the shape. A thin vertical crack in a concrete wall is usually shrinkage, which is rarely serious. A horizontal crack, a crack that is wide at one end and tapers to nothing, or a wall that looks pushed in means the foundation may be moving. For anything but the first kind, book a structural engineer the day you get the report, at $400 to $1,500 a visit.
Key takeaways
- Vertical hairline cracks are common and usually harmless. Horizontal cracks and bowing walls are the ones to worry about.
- Your home inspector describes the crack but isn't required to judge whether the structure is sound. An engineer does that.
- Ask the seller to cover the engineer's evaluation and the repair it specifies, not a round number for "the foundation."
What do the different foundation cracks mean?
The International Association of Certified Home Inspectors (InterNACHI) trains inspectors to read cracks by pattern. Here is each one in its manual's own words:
| What you see | What InterNACHI says | Who should look at it |
|---|---|---|
| Thin vertical crack in the middle of a wall | "Shrinkage cracking is rarely serious," though it is "often mistaken for settlement cracks" | Your inspector, plus an engineer if it's wider at one end |
| Diagonal crack stepping along mortar joints, wider at one end | Settlement cracks "taper, starting large at one end and then diminishing to a hairline crack at the other" | Structural engineer |
| Horizontal crack across a brick or block wall | "Potentially serious, as it indicates that the vertical supporting member -- the foundation wall -- that is carrying a portion of the structure above is bent or broken" | Structural engineer |
| Wall section pushed in or out of line | Settlement can cause "the subsequent buckling or displacement of the foundation wall above" | Structural engineer |
InterNACHI also notes that "vertical cracks in foundation walls are relatively common, and typically result from shrinkage." Its caution is worth keeping in mind: "all cracks are structural but not all of them are structurally alarming." Width alone won't tell you which one you have.
Why won't your home inspector say if it's serious?
It isn't their job. The American Society of Home Inspectors (ASHI) Standard of Practice says inspectors are not required to "offer an opinion about the adequacy of structural systems and components" or "provide engineering or architectural services or analysis."
That's why the report names the crack, maybe recommends further evaluation, and stops. A structural engineer's written opinion is what turns "crack noted" into a scope a repair company can bid on. How to read a home inspection report explains the rest of the report's wording.
How much does foundation crack repair cost?
It depends on what the engineer finds, so the honest answer is a range per repair method.
| Repair | Cost | What it covers |
|---|---|---|
| Structural engineer evaluation | $400 to $1,500 per visit | On-site look and a written opinion on cause and severity (Today's Homeowner) |
| Epoxy or polyurethane injection | $200 to $1,000 | Sealing a stable crack (Fixr) |
| Carbon fiber straps | $4,000 to $12,000 | Stabilizing a bowing wall, the cheaper option (Bob Vila) |
| Steel bracing | $4,000 to $12,000 | Stabilizing a bowing wall, the pricier option (Bob Vila) |
| Piering or underpinning | $10,000 to $40,000 | A sinking foundation, including excavation and temporary jacking (Fixr) |
The spread is wide because these are different jobs. A single injected crack and a house that needs piers have almost nothing in common. Get quotes against the scope your engineer writes, not against this table.
How much does horizontal foundation crack repair cost?
Plan on the wall-movement repairs, not injection. InterNACHI reads a horizontal crack as a wall that is bent or broken, and sealing the crack does nothing about whatever bent it.
Say the engineer confirms a bowing block wall and recommends carbon fiber straps. Your number is the evaluation plus the repair: $400 to $1,500 plus $4,000 to $12,000, or $4,400 to $13,500. If the engineer finds the footing itself is sinking, piering at $10,000 to $40,000 replaces the straps in that math.
How much does concrete foundation crack repair cost?
A narrow vertical crack in a poured concrete wall is usually sealed with injection, at $200 to $1,000. Epoxy is for a dry, stable crack, and polyurethane is for one that leaks.
That price covers sealing, not diagnosis. If the engineer finds the concrete wall is shifting rather than just cracked, you're back to straps, bracing, or piering from the table above.
How do you get a number before your inspection window closes?
Call a structural engineer first, since every repair quote depends on their scope. Then send that scope to two or three foundation repair companies. How to get repair estimates during the inspection period covers the fastest ways to get contractors out.
The rest of your report still needs prices too. Kept prices every line of an inspection report for $79, usually under 4 hours, and marks a structural finding like this one for a professional quote instead of guessing.
What should you ask the seller for?
Ask for the engineer's evaluation first, then the repair it specifies. A line like "east basement wall, horizontal crack: structural engineer evaluation, then repair per the engineer's scope" gives the seller something to act on. "Fix the foundation" does not.
Once you have the engineer's number, decide whether you want the seller to do the work, give a credit, or cut the price. Repairs vs. credit vs. price reduction walks through that choice, and the repair request letter template has the wording. Your contract sets the deadline for the request and any extension, so confirm the dates with your agent.
Should you walk away over a foundation crack?
Not over a vertical hairline crack. A confirmed horizontal crack or active settlement is different, because the repair can run from $4,000 to $40,000 depending on the method. See when to walk away after a home inspection for how to weigh a finding like that.
Is a hairline crack in the foundation normal?
A vertical hairline crack in poured concrete usually is. InterNACHI calls shrinkage cracks relatively common and rarely serious. If it's wider at one end, runs horizontally, or lets water in, have an engineer look.
If your window is closing and you need real numbers for the rest of the report while you wait on the engineer, upload your inspection report to Kept: $79 per memo, usually under 4 hours.
Sources
Cost figures are modeled from public wage and materials data unless a line says observed. Kept is accountable for the numbers on this page, and corrections go to support@usekept.com. How we price.