Basement Waterproofing · Waterproofing Solution

Foundation Crack Injection: Permanent Crack Repair

A leaking crack in a poured concrete wall can be sealed from the inside for good — without excavation — by filling the crack through its full depth with polyurethane or epoxy that bonds to the concrete.

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Quick answer: Foundation crack injection permanently seals a leaking crack in a poured concrete wall by filling it, front to back, with a polyurethane or epoxy resin that bonds to the concrete and flexes with it. It is done entirely from inside the basement with no excavation, and it is the right fix when a single defined crack — not general seepage — is letting water in.

How foundation crack injection works

A poured concrete foundation almost always develops cracks. Concrete shrinks as it cures, and settlement, seasonal soil movement, and pressure add more over the years. Many of those cracks are harmless. The ones that matter are the cracks that carry water — a hairline that weeps after every rain, or an open vertical crack that runs a stream down the wall during a storm.

Crack injection fills that crack through its entire depth, not just the visible surface. We install ports along the crack, seal the face, and inject resin under pressure so it travels all the way through the wall to the soil side. The resin cures into the crack and becomes a permanent part of the wall. Done right, the crack is sealed for good, from front to back, with nothing dug up outside.

Polyurethane vs. epoxy: choosing the right resin

Polyurethane (flexible)

Expands and stays flexible, following the crack and tolerating minor future movement and moisture. The go-to for actively leaking cracks where stopping water is the goal.

Epoxy (structural)

Rigid and extremely strong, it bonds the concrete back together and restores structural continuity across the crack. Used where the crack has a structural component, not just a water one.

The right call

The choice depends on whether the crack is primarily a leak or also a structural concern. We diagnose that first — the resin is only as good as the read on the crack.

When crack injection is — and is not — the right fix

Injection is the ideal, surgical fix when the water is coming through a defined crack in a poured concrete wall. If you can trace a wet streak to a single line in the concrete, that is a crack injection candidate. It solves the problem at the exact point of entry, permanently, without tearing up your yard.

It is the wrong fix in a few important cases, and an honest contractor will say so:

Injection is for poured concrete, not for block walls, whose hollow cores fill and leak differently — those need a different approach.
If water is entering everywhere along the base of the walls or up through the floor, that is hydrostatic pressure and needs an interior drain system, not a crack fill.
If a crack is part of a bowing or moving wall, sealing the leak without addressing the structural movement is treating the symptom. The wall has to be stabilized first.

This is the core of how RDC works: diagnose the cause, not the symptom, and right-size the fix. Injecting a crack that is really a pressure problem is a common way homeowners pay for a repair that does not last.

How RDC performs a foundation crack injection

Confirm it is really the crack

We verify the water is entering through this crack and not arriving from the cove joint or floor. We also check whether the crack is structural or purely a leak, which decides the resin.

Prep and port the crack

The face of the crack is cleaned and injection ports are set at intervals along its length so the resin can be delivered through the full depth of the wall.

Seal the surface

We cap the face of the crack so the injected resin builds pressure and travels backward through the concrete instead of leaking out the front.

Inject under pressure

Resin is pumped in from the bottom port upward until it fills the crack front to back. For an active leak, flexible polyurethane expands to fill every void; for a structural repair, epoxy welds the concrete back together.

Cure and finish

Once cured, the ports are removed and the wall is cleaned up. The crack is sealed permanently with no exterior excavation and no landscaping to repair.

What to expect afterward

Crack injection is one of the faster, less invasive waterproofing repairs — a single crack is often handled in a matter of hours, entirely inside. Because polyurethane stays flexible, it tolerates the small seasonal movements a foundation makes without re-opening. There is essentially no ongoing maintenance on the injection itself. What we do watch is new cracks: if a wall keeps producing them, the real story may be soil pressure or movement, and we will point that out rather than just selling you injection after injection.

Why homeowners trust RDC

RDC Restoration has repaired New Jersey foundations for more than 27 years, earning over 1,000 five-star reviews as an IICRC-certified, NORMI- and AHERA-credentialed, BBB A-rated company serving the entire state from Berkeley Heights and Piscataway. We also handle water damage and mold, so we understand what a leaking crack does over time and we fix it before it becomes a mold problem. Every crack repair starts with a free inspection, an honest read on whether injection is the right fix, and a warrantied price in writing.

Common questions

Foundation Crack Injection: Permanent Crack Repair — FAQs

Is foundation crack injection a permanent fix?

Yes, when the crack is genuinely a leak rather than a symptom of ongoing structural movement. The resin fills the crack through the full depth of the wall and bonds to the concrete, so the sealed crack does not leak again. Flexible polyurethane even tolerates the small seasonal movements a foundation makes. The one caveat is that if the wall keeps moving, new cracks can form elsewhere, which is why we diagnose the cause first.

Do you have to dig up my yard to fix a foundation crack?

No. Crack injection is done entirely from inside the basement. We inject resin through the crack from the interior until it fills all the way to the soil side of the wall. There is no excavation, no torn-up landscaping, and no exterior drainage to restore, which is what makes it so much less invasive than digging down to the footing outside.

Should I use epoxy or polyurethane for my crack?

It depends on the job. Polyurethane is flexible and expands to chase an active leak, so it is the usual choice when stopping water is the goal. Epoxy is rigid and structural, welding the concrete back together where the crack has a load-bearing concern. We determine which your crack needs during the inspection rather than defaulting to one product.

Can you inject cracks in a block or cinder-block wall?

Standard crack injection is designed for poured concrete walls. Hollow block walls hold and release water differently through their cores, so they usually call for a different solution such as an interior drainage system or wall-channel approach. We will tell you which wall type you have and the right method for it at the free inspection.

How do I know if my crack is structural or just leaking?

Leaking cracks are typically thin and vertical and produce water without the wall moving. Structural cracks may be wider, stair-stepped, horizontal, or accompanied by a wall that is bowing or shifting. A structural crack needs the movement addressed before or along with sealing. We assess this on site so you are not just sealing a symptom.

How much does foundation crack injection cost?

A single straightforward crack is one of the more affordable waterproofing repairs, but the price depends on the crack's length, depth, and whether a structural epoxy repair is involved. We give a firm written price after a free inspection and never quote sight-unseen, because misdiagnosing the crack is the costly mistake.