Horizontal cracks in a foundation wall

Yes, and this is the one page in this library that exists mainly to point you away from us and towards someone who can see your house.

A horizontal crack in a foundation wall is not automatically an emergency and it is not automatically a catastrophe. But it can be associated with lateral pressure from the soil outside the wall, and lateral pressure is a load question. Load questions are answered by licensed engineers, not by websites and not by whoever is quickest to send a quote.

What it is

A horizontal crack runs parallel to the floor, across the face of the wall rather than up and down it. In a block wall it often follows a mortar course; in poured concrete it can run across the middle third of the wall height.

The reason direction matters so much here is what it implies about the direction of force. A vertical crack in a wall is frequently associated with shrinkage or with settlement below. A horizontal crack is more often associated with pressure pushing on the wall from outside, which the wall is resisting in bending.

Any accompanying inward bow, lean, or displacement of the wall along the crack line is the observation that matters most. A wall can crack horizontally and remain in plane; a wall that has moved inward along the crack is a different situation.

What seeing this cannot establish

• This page cannot tell you whether your wall is safe. Nobody can, from a description or a photograph. Wall thickness, reinforcement, backfill height, soil type, drainage and what the wall is carrying all bear on it and none of them are visible in an image.
• The absence of an obvious bow does not establish that the wall is fine, and the presence of a horizontal crack does not establish that it is failing.
• A crack that has been there for decades and a crack that appeared this spring can look identical. Age is not readable from the crack.

What this can be associated with

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

• Lateral pressure from saturated backfill, which can be associated with poor exterior drainage or downspouts discharging beside the wall
• Frost action in backfill against an uninsulated wall in a freezing climate
• Heavy equipment, fill, or vehicle load placed close to the wall above the backfill
• Expansive soil against the wall, which can increase pressure as it takes on moisture
• Backfill placed and compacted against the wall before the structure above was able to brace it

What you can safely check yourself

• Stand at one end of the wall and sight along its face at eye level. A bow is far easier to see along the wall than square on to it. Photograph what you see.
• Hold a long straightedge or a taut string line vertically against the wall from floor to ceiling, and photograph any gap behind it at the crack line.
• Photograph the full wall, then the crack, then the ends of the crack where it meets a corner or an opening.
• Look outside directly behind the crack. Note downspout discharge points, grade sloping towards the house, planting beds that hold water, and anything heavy parked near the wall.
• Note whether the crack is wet, whether it has ever leaked, and whether there is efflorescence — a white mineral deposit — along it.
• Do not excavate against the wall to have a look. Removing the soil that is currently there changes the loading on a wall you already have questions about.

When professional evaluation matters more

• Always, for this condition. A horizontal crack in a foundation wall is the clearest case in this library for a licensed structural or geotechnical engineer to look at it before any repair is priced.
• With more urgency if the wall is visibly bowed, leaning, or displaced along the crack
• With more urgency if the crack has widened, lengthened, or the bow has increased since you first noticed it
• With more urgency if the crack appeared suddenly, or after excavation, heavy rain, or equipment working near the house

When replacement enters the conversation

• This is not a repair-or-replace decision a homeowner should be making from a web page. It is an engineering assessment, and the assessment determines the options.

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 sighting along the wall face to show whether it is in plane
• A vertical straightedge or string line photograph at the crack
• The date you first noticed it, and any dated photographs you already have
• Photographs of the exterior grade, downspouts and any load close to the wall
• Notes on any recent excavation, landscaping, drainage change or unusually wet season

Questions to ask whoever comes out

• Before this: have you had an engineer look at it? If not, that is the call to make first.
• To an engineer — is the wall stable as it stands, and what is your basis for that?
• To an engineer — does the exterior drainage need addressing as part of any solution?
• To a contractor working from an engineer's report — which parts of your scope come from that report, and which are your own additions?
• To a contractor — what happens if the recommended work is done but the drainage is not?

Where estimates for this commonly differ in scope

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

• Repair proposals for horizontal wall cracks vary enormously in what they actually address — some treat the crack, some reinforce the wall, some address the pressure causing it, some do all three. Without an engineer's assessment there is no basis for comparing them.
• A proposal that treats the crack cosmetically and a proposal that reduces the load on the wall are not the same product at different prices.
• Sealing a wall crack can stop water and change nothing about the pressure. Both can be legitimate goals; they should not be confused with each other.

Who tends to do this work

• A licensed structural or geotechnical engineer
• A waterproofing contractor
• A drainage contractor or landscaper who does grading

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