Basement cracks appear in two locations: the floor slab and the interior wall face. Both need attention before freeze-thaw cycles or water pressure make them worse. Laval Concrete routes and seals floor cracks with flexible material, and injects interior wall cracks with polyurethane that bonds and moves with the concrete. Structural cracks get referred to our foundation repair team. Free assessment, written quote.
The basement floor slab and the foundation wall face crack for different reasons and respond to different repairs. Floor cracks typically stem from shrinkage during curing or settlement of the base underneath. Wall cracks usually telegraph through from the exterior, where water or soil pressure is working on the outside of the foundation. Understanding which you have determines the fix.
Floor cracks are routed open with a concrete saw to create a clean channel, then filled with a flexible sealant that accommodates seasonal movement without re-opening. Interior wall cracks receive polyurethane injection through small ports drilled along the crack line. The material flows into the crack, bonds to both sides, and flexes as the concrete moves. Both methods stop water from entering at that point.
When a crack shows signs of structural movement, we identify it and recommend foundation assessment rather than a basement-only patch. If water is the issue, we pair crack repair with basement waterproofing to address the source. The goal is a lasting fix, not a temporary seal.
Recent work
The repair sequence
How Laval Concrete Seals Basement Cracks
Inspect and document each crack
We photograph, measure, and classify every visible crack in the slab and along the interior wall surface. This tells us whether each is shrinkage, settlement, or water-driven, and guides the repair method.
Route floor cracks to clean profile
Floor cracks are cut open with a concrete saw to a V or square profile, vacuumed clean of dust and debris, and left dry and ready for sealant application.
Seal or inject based on location
Floor cracks receive flexible sealant pushed full-depth into the routed channel and finished flush. Wall cracks get polyurethane injected through ports drilled along the crack, bonding the concrete on both sides.
Why Basement Cracks Come Back Without Root Cause Work
Sealing a crack stops the leak at that moment, but if the cause is still active, the crack will return. A floor crack above an old plumbing trench will re-open as the base continues to settle. An interior wall crack weeping water will keep weeping if the exterior drainage is poor or the foundation is under soil pressure.
Our repair includes identifying what caused each crack. Sometimes that means a follow-up visit to rebuild the base under the slab. Sometimes it means improving exterior drainage or installing a new basement slab with proper support. Sometimes it means engaging the foundation repair side for structural work. The quote tells you what the lasting fix is, not just what the crack repair costs.
Floor vs. wall cracks, sealing methods, injection, and when a crack signals a bigger problem.
Yes. Slab cracks get routed to a clean profile and sealed with a flexible material that handles small seasonal movement. Wall cracks on the inside face get polyurethane injected through ports along the crack. The repair matches the crack.
Not always. Some are dry hairlines that are cosmetic for now but worth sealing before water finds them. Others are already wet and need the cause addressed, drainage, an exterior crack, or a structural issue, alongside the crack repair itself.
Yes. Horizontal cracks usually mean soil pressure is pushing the wall and the right answer is structural; we refer those to foundation crack repair on the engineered side rather than injecting from inside.
It will stop the leak at that specific crack. If the basement is wet in multiple places, the root issue is usually drainage rather than the cracks themselves; the right answer is also interior waterproofing to address the cause.
Most basement crack visits are a few hours to a full day, depending on how many cracks and whether they are slab or wall. The slab repairs cure within hours; injected wall cracks cure overnight. The timeline is on the quote.
Homeowner reviews
What Laval Homeowners Say About Basement Crack Repairs
Slab crack above an old plumbing trench got routed and sealed properly, and they said up front the base under it was the real cause. Honest call, the crack stayed sealed.
Q. B.
Laval
★★★★★
Three slab cracks and one interior wall crack all in one visit. They classified each, repaired each the right way, and the basement is dry through the season.
X. K.
Montreal
★★★★★
They flagged my horizontal wall crack as structural and referred it up rather than just injecting. Could have charged me and walked away. Glad they did the right thing.
Z. E.
Longueuil
★★★★★
Routed slab cracks instead of just smearing sealer on top like the last guy did. The repair has held through two springs of melt. Real method, real results.
F. V.
Terrebonne
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Describe the cracks you see in your basement, whether they are in the floor or walls, dry or wet, and we will visit free to assess them and provide a written repair quote.
