How do concrete contractors in NB handle large crack repairs in foundations?

For large cracks in NB foundation walls, professional contractors use one of two primary methods depending on whether the crack is actively leaking and whether structural movement is involved: epoxy injection for structural cracks that are dry and stable, and polyurethane foam injection for actively leaking cracks. Understanding which method applies to your situation is the first step.

Epoxy injection fills the crack with two-part epoxy resin that, when cured, creates a bond stronger than the surrounding concrete. It is the appropriate choice for cracks that are dry (not actively transmitting water), stable (not still moving), and where the goal is to restore structural continuity to the wall. The contractor drills ports into the crack at regular intervals (typically 8 to 12 inches apart), installs injection ports (small plastic fittings), seals the crack face between ports with epoxy paste, then injects low-viscosity epoxy from the lowest port upward. The epoxy flows into the crack under gentle pressure and cures to full strength in 24 to 72 hours. Cost in NB: approximately $500 to $1,000 per crack for a typical 6 to 8 foot vertical crack in a residential foundation.

Polyurethane foam injection uses a flexible, water-reactive foam that expands when it contacts moisture within the crack. It is the go-to method for actively leaking cracks — the foam reacts with the water, expands to fill the crack, and stops the leak. Unlike epoxy, polyurethane remains somewhat flexible after curing, which allows it to accommodate minor future movement without re-cracking. It does not restore structural strength the way epoxy does, but for a non-structural crack that is leaking, it is highly effective. Cost is similar to epoxy injection: $500 to $1,500 depending on crack length and access.

Before choosing the repair method, the contractor must assess the crack type. Vertical cracks in poured concrete foundations — very common in NB — are typically caused by concrete shrinkage during curing and are usually non-structural. Horizontal cracks are a different story entirely and may indicate lateral soil pressure or frost heave forces pushing against the wall — these require structural assessment and possibly wall reinforcement (carbon fibre straps, wall anchors, or underpinning) before any crack filling makes sense.

For NB homes specifically, spring is when foundation cracks become most active — snowmelt and spring rain saturate the soil and increase hydrostatic pressure. This is when leaks announce themselves most dramatically. But the right time to repair is after things dry out in May or June, when contractors can properly diagnose the crack and apply products under dry conditions.

Never attempt injection repair as a DIY project on a structural crack or a crack showing signs of wall movement. Get a professional assessment — the wrong repair approach wastes money and may mask a worsening problem. New Brunswick Concrete can connect you with foundation repair specialists throughout NB.