Foundation Crack Repair · Cambridge
Foundation Crack Injection & Repair in Cambridge
Low-pressure polyurethane injection for leaking poured-concrete cracks — plus honest advice when your wall is stone or block and injection isn't the answer.
A leaking foundation crack is the most common wet-basement call we get from Preston and Hespeler, and there's a reason it's local: both areas sit on dense clay till. When that clay saturates in spring melt or a summer downpour, it swells and pushes against the foundation. Poured walls respond by opening hairline shrinkage cracks — usually vertical, often starting at a window corner or where the wall steps — and hydrostatic pressure drives water through them. One wet spring is often all it takes for a dry crack you've ignored for years to start running.
How crack injection works
We inject expanding polyurethane resin into the crack under low pressure from the inside face. The resin travels the full thickness of the wall — right out to the soil — filling the void and curing into a flexible, watertight seal that moves with the seasonal freeze-thaw cycle instead of shattering like rigid patches do. There is no excavation, no landscaping damage, and most single-crack repairs are done in under two hours. Typical cost is $400–$1,000 per crack, which makes injection by far the cheapest permanent fix in waterproofing when it's the right one.
When injection is NOT the right fix
Cambridge has a lot of foundations that should never be injected. Galt's rubble-stone and fieldstone walls leak through deteriorated lime mortar over broad areas — resin has nothing to seal. Concrete block walls carry water inside their hollow cores, so sealing one face just moves the exit point. Horizontal cracks with inward bowing are structural and need engineering, not resin. Part of our assessment is telling you which of these you have, even when the honest answer is a bigger job than you hoped — or a smaller one.
What's included
- Crack mapping and moisture-source confirmation
- Low-pressure polyurethane injection, full wall depth
- Surface port removal and tidy finish
- Assessment of grading, downspouts and window wells feeding the crack
- Written warranty on every injected crack
Frequently asked questions
How much does foundation crack injection cost in Cambridge?
Most single-crack polyurethane injections run $400–$1,000 depending on crack length, width, and access. Multiple cracks injected on the same visit cost less per crack. See our 2026 cost guide for full ranges.
Why did my foundation crack in the first place?
In Preston and Hespeler the usual culprit is clay soil: it swells when saturated and shrinks in drought, cycling pressure on the wall. Normal concrete shrinkage in the first years after pouring, and Cambridge's hard freeze-thaw winters, account for most of the rest.
Is polyurethane or epoxy injection better?
Polyurethane for waterproofing — it expands to fill the full crack depth and stays flexible through seasonal movement. Epoxy is for structural bonding when an engineer specifies it. Most leaking Cambridge basement cracks call for polyurethane.
Can you inject a crack in a stone foundation?
No — and be wary of anyone who says yes. Rubble and fieldstone walls seep through mortar joints across a wide area, so they need repointing and interior drainage, not injection. We'll tell you honestly which situation you have.
Will the crack come back?
The injected crack itself is sealed through the full wall thickness and warrantied. If the underlying cause is ongoing movement or drainage failure, we identify that during assessment so you're fixing the disease, not one symptom.
Serving Cambridge and surrounding areas. Contact us for a free, no-obligation quote specific to your project.