Cracks in basement walls start small and get worse. Water enters through the opening, freezes, expands, and the crack widens. What looked minor in fall becomes a leak by spring. Laval Concrete inspects the crack, determines if it is active or stable, then injects or seals it to stop water and movement. Every assessment is free and every quote is written.
A foundation crack that is dry and stable today can become a weeping crack after one freeze-thaw cycle. The slab and wall move slightly as the ground shifts and the concrete cures, creating hairline separations. Most are harmless until water finds them.
We measure and photograph each crack, determine whether it runs vertically or horizontally, and assess whether it is actively moving or stable. Vertical hairlines that are dry get sealed at the surface. Cracks that are weeping or actively widening get polyurethane injected through ports drilled into the wall, creating a flexible bond that moves with the concrete.
We measure, photograph, and classify each crack as vertical or horizontal, active or stable, dry or weeping. This determines whether the repair is a surface seal or a full-depth injection.
Route and prepare the surface
The crack is routed to a clean profile where needed, dust and loose material are removed, and injection ports are spaced along the crack so the material reaches the full depth.
Inject polyurethane or epoxy
Polyurethane is used for active or weeping cracks because it flexes and expands on contact with water. Epoxy is used when a rigid, permanent bond is the goal. The material is injected through the ports under pressure.
Cure and finish
After the material sets, ports are trimmed, the wall is cleaned, and the repair is inspected. We often recommend pairing with foundation work or basement crack sealing for complete protection.
Not all cracks are the same
When Horizontal Cracks Mean Structural Work
Vertical hairline cracks are common and routine. Horizontal cracks across a wall, stair-step patterns in block, or cracks that change width seasonally suggest the wall is under pressure or moving. These are structural issues, not cosmetic ones.
When we see those patterns, we flag them immediately and refer to underpinning or structural foundation repair rather than just injecting over the problem. We will not seal a crack that is a symptom of a bigger issue.
Hairlines, horizontals, polyurethane injection, and when to call for structural help.
Most do, even hairline ones, because once water gets in and the freeze-thaw cycle takes over, a cosmetic crack becomes a leak. Sealing or injecting it early is much cheaper than fixing it after it has opened up.
Polyurethane is flexible, expands on contact with water, and is our default for active or weeping cracks. Epoxy is rigid and structural, used when bonding the two sides of the crack permanently is the goal. We choose based on the crack.
Yes, most cracks are injected from the inside through ports drilled into the wall, which avoids excavation. Exterior repair is reserved for cases where outside conditions are causing the crack or where pairing with waterproofing is the right call.
Usually yes. Horizontal cracks suggest the wall is being pushed by soil pressure or water; that is a structural issue and gets referred up to foundation repair. Vertical hairlines are usually just shrinkage and routine to fix.
A typical injection takes a few hours and the crack is sealed by the end of the visit. Larger or multiple cracks may take a day. The timeline is in the written quote so you know up front.
Hairline crack started weeping last spring. Injected from inside in one visit, sealed up properly, and it has stayed dry through the next season. Cheap and done.
H. W.
Laval
★★★★★
They flagged one of my cracks as horizontal and recommended a structural look instead of just injecting. Could have charged me, didn't. That kind of honesty is rare.
I. R.
Longueuil
★★★★★
Three vertical cracks injected in one visit. No mess, no fuss, no return leaks. Quote was firm, work was clean, ports trimmed off so you barely see them.
P. N.
Montreal
★★★★★
Classified each crack on the wall and only repaired the ones that needed it. The rest were stable shrinkage and didn't need a thing. Saved real money.
V. L.
Terrebonne
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Describe the cracks you see, where they are located, their size, and whether they leak. We will inspect the wall at no charge and provide a written quote for any repair work needed.
