Can a Foundation Crack Be Repaired From the Inside?
Updated October 2026
Yes, in many cases. A leaking or dry crack in a sound poured concrete wall is commonly injected from the inside of the basement, with resin filled through the full depth of the wall. Inside injection fits an isolated crack in a wall that is not moving. It does not fit a bowing wall, a repeating pattern of cracks, block walls, or water pushing against the outside of the wall; those need reinforcement, exterior work or drainage. A free written quote starts with a visit and measurements, so you see which kind you have.
Homeowners often picture a foundation crack repair as a big dig around the house. For many cracks it is nothing like that. A crack in a poured concrete wall that is not moving is commonly fixed from inside the basement. The question is whether yours is that kind of crack.
What an inside repair is
The repair is injection. Resin goes into the crack and fills it to full depth, front to back, not just across the inside face. That is the difference from a surface smear of hydraulic cement or caulk, which plugs the face while the crack behind it stays full of water and opens again with freeze-thaw. Epoxy and polyurethane suit different cracks: epoxy glues a dry, dormant crack back together, and polyurethane foams to seal a damp or leaking one and flexes with the wall through the seasons.
When inside injection is the right fix
Inside injection is the right fix for an isolated crack in a sound poured wall. A leaking but stable crack in a poured wall is usually a polyurethane job. A dry structural crack that is not moving is usually an epoxy job. It is the smaller job for the smaller problem, and it needs no digging outside.
When it is not enough
Injection fills a crack. It does not hold a wall against a force that is still pushing on it. Inside work alone falls short when:
- the wall is bowing inward, which is a job for reinforcement such as carbon fibre straps, as bowing basement wall signs explains;
- cracks repeat in a pattern around the foundation;
- a crack keeps opening over the seasons, which points to pressure from the soil outside;
- the crack leaks in several places or along a whole wall, which is a water problem, and the fix is water management rather than more filler;
- the wall is concrete block, where a leak tracks through the cores and joints instead of one clean line.
In those cases, injecting only the crack buys a season before it comes back. If you are not sure which side of that line your crack sits on, a crack that keeps getting wider shows how to measure and track it, and the foundation crack types guide shows what each direction means.
Inside or outside: how the call is made
The method follows the crack and the water, not a preference. Interior work is the smaller, less disruptive route and goes in during any season. Work from outside needs ground you can dig and unfrozen soil, and it treats the wall at the source. Interior and exterior waterproofing compares the two.
What it costs
We publish no price, because the type of fix drives the number, not a flat rate. What drives a foundation crack repair’s price lists the factors.
Get a straight answer
Foundation repair starts with a free written quote. We measure the crack, tell you plainly whether it is a crack problem or a wall problem, and put the quote in writing, with a lifetime warranty on labour.
Can a foundation crack be repaired from the inside?
Often, yes. A crack in a poured concrete wall that is not moving is commonly injected from the inside, with resin filled front to back through the thickness of the wall. Epoxy suits a dry, dormant crack and polyurethane suits a leaking one.
Does an inside repair stop water getting to the wall?
It seals the crack so water cannot come through it. It does not keep the outside of the wall dry. When water is pressing along a long run of wall, the real fix is water management, not more filler.
When is an inside repair not enough?
When the wall is bowing, when cracks repeat in a pattern around the foundation, when a crack keeps opening over the seasons, or when the real issue is water sitting against the outside of the wall. Those cases need reinforcement, exterior waterproofing or drainage.
Can a block foundation be repaired from the inside?
Injection is built for poured concrete walls. In a hollow block wall a leak tracks through the cores and joints rather than one clean crack, so the fix is usually different. A look in the basement confirms what you have.
How do I find out which repair my crack needs?
Our free written quote starts with a visit and measurements: width, direction, movement over time and offset. The quote names what the crack is doing and why, in plain words.