Vertical cracks in a foundation wall

Vertical cracking in a poured foundation wall is common, and a large share of it is associated with the same drying shrinkage that produces fine cracks in flatwork. That does not make it uninteresting — a vertical crack is frequently the route water takes into a basement, and that is worth dealing with even when the wall itself is not in question.

The useful work here is separating three different questions that a vertical crack raises at once: is the wall moving, is water getting in, and is the crack changing.

What it is

A vertical crack runs up and down the wall, roughly perpendicular to the floor. In poured walls it frequently starts at the top of the wall or at a form tie and runs down, often narrowing as it goes. It very commonly appears near an opening — a window, a beam pocket, a service penetration — because those interrupt the wall's continuity.

The taper is worth noticing. A crack that is widest at the top and narrows to nothing lower down behaves differently from one of even width, and differently again from one widest at the bottom.

In a block wall, cracking tends to follow the mortar joints in a stepped path rather than running as one clean vertical line, which is a different pattern with a different reading.

What seeing this cannot establish

• A vertical crack does not establish that the foundation is settling, and its absence does not establish that it is not.
• Width in a wall crack is less informative than whether the two faces have moved out of plane with each other. A crack you can see through matters differently from a crack where one side has stepped forward.
• Whether the crack is full thickness through the wall is not visible from inside, and it determines whether water can travel through it.
• A crack that leaks is not necessarily a crack that is moving, and a crack that is moving is not necessarily one that leaks. They are separate findings.

What this can be associated with

Candidate explanations, not findings. Nobody can establish which applies to your concrete without seeing it.

• Drying shrinkage in a poured wall, which is the most common association for a fine, tapering vertical crack
• Stress concentration beside an opening or a penetration, where the wall has less continuous section
• Settlement of the footing below one part of the wall, which can be associated with a crack that widens towards the bottom
• Soil moisture change against the wall over seasons, which can open and close a crack cyclically
• Backfill settlement drawing the wall outward slightly at one point

What you can safely check yourself

• Note where the crack is widest — top, bottom, or even. Photograph the crack at top, middle and bottom with something for scale.
• Run a finger across the crack in several places to check whether one face has moved forward of the other. Out-of-plane movement is a more significant observation than width.
• Look for efflorescence — a white powdery mineral deposit — along or beside the crack. It indicates water has moved through, even if the crack is dry today.
• Note whether the crack ever weeps after heavy rain or snowmelt, and photograph it wet if it does.
• Check outside directly behind the crack: where roof water lands, which way the grade falls, and whether anything holds water against the wall.
• Mark the crack ends in pencil with a date. Length change over a year is more useful than any single-day measurement.

When this is frequently cosmetic

• A fine vertical crack in a poured wall, tapering to nothing, dry, with both faces in plane and no change over time
• A crack beside an opening that has been present since the house was young and has not altered

When professional evaluation matters more

• One face of the crack has moved out of plane with the other
• The crack is wider at the bottom than the top, which can be associated with footing movement rather than shrinkage
• The crack is actively leaking, or efflorescence shows a persistent water path
• The crack has widened or lengthened between dated observations
• Cracking appears in a stepped pattern through block courses, or in several places along the same wall
• Doors, windows, or floors above the wall have changed behaviour

Evidence worth having before you ask for estimates

Every item here is something you can produce without tools or risk, and every one of them makes an estimate more accurate.

• Photographs at top, middle and bottom with scale, dated
• A note of the widest point and whether the faces are in plane
• Any efflorescence, photographed
• Exterior photographs showing downspouts, grade direction and anything retaining water
• Dated pencil marks at the crack ends for length monitoring

Questions to ask whoever comes out

• Do you read this as shrinkage, settlement, or water, and what makes you say so?
• Are you proposing to stop water, to restore the wall, or both? Which parts of the price are which?
• If you inject the crack, what happens if the wall keeps moving seasonally?
• Does anything need doing outside — drainage, grade, downspouts — for this repair to hold?
• Would you want an engineer to see this first, and if not, why not?

Where estimates for this commonly differ in scope

These are the places two prices for apparently the same work stop being comparable.

• Crack injection to stop water and structural repair to restore a wall are different scopes at very different prices. An estimate should say which it is.
• Interior water management and exterior drainage correction address the same symptom from opposite directions. Comparing one of each without noticing is a common way to pick badly.
• Some proposals include a warranty against water entry and some against structural movement. Those are not the same promise.

Who tends to do this work

• A waterproofing contractor
• A licensed structural or geotechnical engineer
• A concrete repair specialist

ConcreteOwner does not inspect, certify or approve contractors. This describes which trade usually holds this work, not a recommendation of anybody in particular.