Water entering through concrete cracks

Two things are true and they need separating. The crack is a crack, with whatever significance its direction, location and behaviour give it. And the crack is a path, delivering water from wherever it is arriving to wherever it is appearing.

Treating them as one problem is how homeowners end up paying to seal a crack while the reason water arrives at it remains untouched.

What it is

Water needs three things to appear through a crack: a source, a path, and pressure or gravity to move it. The crack is only the path, and it is usually the least expensive of the three to alter — and the least effective place to intervene.

The source is almost always outside: roof water discharging beside the wall, ground sloping towards the house, a saturated backfill zone, or surface water with nowhere else to go.

The timing tells you a great deal. Water that appears during rain suggests a direct surface path. Water that appears a day or two later suggests groundwater rising. Water that appears regardless of weather suggests a plumbing source.

What seeing this cannot establish

• A leaking crack does not establish that the crack is structurally significant, and a structurally significant crack does not necessarily leak.
• Where water appears inside is not where it entered. Water travels along paths you cannot see.
• The volume appearing inside does not indicate the size of the source.
• Whether the crack is full thickness cannot be determined from one face.

What this can be associated with

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

• Roof water discharging beside the wall, which is the most common and most fixable association
• Ground sloping towards the building rather than away
• Saturated backfill against the wall raising hydrostatic pressure
• A blocked or failed perimeter drain, where one exists
• Surface water from a driveway, patio or neighbouring property directed towards the wall
• A plumbing or irrigation leak, which is the case that shows no correlation with rainfall

What you can safely check yourself

• Note the timing relative to rain: during, hours after, days after, or unrelated. This single observation narrows the source more than anything else.
• Photograph the crack wet, and photograph where the water first appears rather than where it collects.
• Look for efflorescence — white mineral deposit — which marks a persistent water path even when dry.
• Go outside during rain and watch. Photograph where downspouts discharge, where water pools, and which way the ground falls.
• Check gutters and downspouts for blockage and for discharge close to the wall.
• Note whether the appearance correlates with irrigation rather than rain, which points at a different source.

When professional evaluation matters more

• The crack is horizontal, or the wall is bowed — that is a structural question first and a water question second
• Water volume is substantial, or appears in multiple locations
• There is no correlation with rainfall, which raises a plumbing source worth investigating
• Efflorescence or damp extends well beyond the crack itself
• The crack is widening as well as leaking

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.

• The timing pattern relative to rain, written down over several events
• Photographs of the crack wet and of the first point of appearance
• Exterior photographs during rain showing downspouts, pooling and grade
• Any efflorescence, photographed
• Gutter and downspout condition
• Water meter readings if a plumbing source is possible

Questions to ask whoever comes out

• Where do you think the water is arriving from, and what outside needs changing?
• Are you proposing to stop water, to address the crack structurally, or both? Which part of the price is which?
• If the crack moves seasonally, will the material you are using survive that?
• What is the cheapest thing that would make a real difference here, even if it is not your work?
• If this is sealed and water then appears somewhere else, what does that tell us?

Where estimates for this commonly differ in scope

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

• Interior crack injection and exterior drainage correction address the same symptom from opposite ends, at very different prices, and are frequently compared as if they were alternatives when sometimes both are needed.
• Warranties may cover water entry, structural movement, or neither. Establish which.
• Gutter and downspout work is often the cheapest effective intervention and is almost never in a waterproofing estimate.

Who tends to do this work

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

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