Epoxy is a rigid, structural resin. We seal the surface of the crack, then inject epoxy under pressure through a series of ports so it fills the crack from the inside out and bonds to the surrounding concrete. Once cured, the crack is effectively welded shut and regains much of the wall’s original rigidity at that point. Epoxy is the right choice for dry, stable cracks where restoring strength matters more than flexibility.
Polyurethane expands as it cures and stays flexible afterward, so it follows the crack even if the wall moves slightly with the seasons. It’s the standard choice for actively leaking cracks, since it expands into voids water is already using as a path through the wall and cures even in damp conditions. It won’t restore structural rigidity the way epoxy does, so we don’t use it where load-bearing strength is the priority.
We start by cleaning the crack and installing a series of injection ports directly over it, spaced according to the crack’s length and width. A surface seal goes over the crack between the ports, then the epoxy or polyurethane is injected under controlled low pressure, starting from the bottom port and working up so the material fully fills the crack rather than pooling. Once cured, the ports and surface seal are ground flush, leaving a clean, sealed line rather than a visible patch.
Epoxy, for a rigid, structural seal.
Polyurethane, for flexible, water-tolerant sealing.
Polyurethane, since it flexes rather than cracking again alongside it.
Crack injection typically runs $300 to $1,200 per crack, with the range driven mainly by crack length, accessibility, and whether it’s a simple straight crack or one with multiple branches that each need their own injection ports. A crack behind finished drywall or in a hard-to-reach corner takes more labour than an open, accessible basement wall. We do not make blanket guarantees on this site – any workmanship warranty on a specific injection job is set out in your written quote once the scope is confirmed.
An epoxy or polyurethane injection is a permanent repair to that specific crack, but it’s still worth watching the surrounding wall for a season or two, particularly through spring thaw when hydrostatic pressure is highest. If grading or downspouts direct water toward the foundation near the repair, correcting that will reduce the chance of a new, separate crack forming nearby. The injected crack itself shouldn’t reopen or need re-treatment once it’s fully cured.
The choice isn’t cosmetic. Epoxy creates a rigid, structural bond that’s appropriate for a stable, dry crack where restoring strength to the wall matters. Polyurethane stays flexible after curing and expands to fill voids, which makes it the better choice for a crack that’s actively leaking or one that may still see minor seasonal movement. We check whether the crack is dry or damp, moving or stable, and how wide it is before choosing, rather than defaulting to one product for every job. We also check whether a crack has any active efflorescence, the white mineral deposit left behind as water evaporates through concrete, since it’s a useful sign of how long moisture has been moving through that specific crack.
The crack face is cleaned and sealed with injection ports set along its length.
Resin is injected from the bottom port up so it fully fills the crack.
Ports are removed once cured and the seal is checked before we call the job done.
Tell us what you're seeing and where it is on the property.
We inspect the affected area, confirm the cause, and check whether it's still active.
A specific scope of work and price in writing before we schedule anything.
Work is carried out to the agreed scope, then we review it with you and confirm it matches the quote.
Polyurethane tolerates minor ongoing movement better than epoxy. A crack tied to active structural movement needs that movement addressed first, or the injection can fail.
Initial cure is typically a few hours; both products reach full cure within about 24 hours, after which the wall can be finished or painted.
Epoxy restores a meaningful amount of the wall's original rigidity at the injected crack. Polyurethane seals the crack against water but is not chosen for structural strength.
Typically $300-$1,200 per crack for a straightforward poured-concrete injection, depending on crack length and accessibility. Your written quote will confirm the exact price.
The ports and surface seal are ground flush once cured, leaving a thin line rather than a raised patch. It's rarely invisible, but it's not a rough repair either.
Interior injection can generally be done year-round since it's not weather-dependent the way exterior excavation is.