Foundation & basement crack repair

Foundation crack repair in Durham Region

Most basement cracks are harmless. Some let water in, and a few point to a structural problem. Here's how to tell them apart, what the fixes cost around Durham, and how to get one looked at.

Get matched with a contractor How it works

Durham Crack Repair is a free referral service, not a contractor. Here's how we work.

What kind of crack do you have?

Crack	What it usually means	Typical fix
Thin vertical or slightly diagonal, poured concrete	Shrinkage as the concrete cured. Very common and not structural.	Leave and monitor if dry. Inject if it leaks or gets damp.
Crack that leaks after rain or snowmelt	Water pressure in the soil is pushing through the crack.	Polyurethane injection from inside, or exterior excavation and membrane if injection isn't possible.
Diagonal from a window corner	Stress concentrates at corners. Usually shrinkage or minor settlement.	Injection. Check the window well drains properly.
Horizontal, partway up the wall	Lateral soil pressure (often frost or saturated clay) pushing the wall in.	Structural assessment first. May need wall bracing, anchors or excavation.
Stair-step along block mortar joints	Differential settlement or soil pressure on a block foundation.	Structural assessment. Repair depends on cause.
Wider than 6 mm, or one side offset	Movement beyond normal shrinkage.	Structural assessment before any sealing.

Get it checked soon if: the crack is horizontal or stair-stepped, the wall bows, doors or windows upstairs start sticking, or the crack has visibly grown in weeks or months. Sealing over a moving crack hides the problem without fixing it.

The main repair options

1. Interior crack injection (most common)

The contractor seals the face of the crack, sets ports along it, and pumps in polyurethane (flexible foam that expands to block water, used for leaks) or epoxy (rigid and bonds the concrete back together, used where strength matters). It takes a few hours, with no digging and no disruption outside. More on crack injection →

2. Exterior excavation and membrane

The contractor digs down to the footing along the crack, cleans and seals the wall from outside, applies a waterproofing membrane, and backfills. It's used when the inside can't be reached (a finished wall they can't open), for block walls, or when injection has already failed. It's more expensive and needs utility locates before digging.

3. Structural repair

For horizontal cracks, bowing walls or settlement: wall anchors, steel or carbon-fibre bracing, or in serious cases underpinning. This usually starts with a structural engineer's report and often needs a building permit.

What foundation crack repair costs around Durham

Typical 2026 prices for the Toronto–Durham area. They're ranges drawn from published local price guides, not quotes. Your price depends on crack length, wall height, access and whether the basement is finished.

Repair	Typical cost (CAD)
Interior injection, dry or damp crack	$500 – $1,500 per crack
Interior injection, actively leaking crack	$1,200 – $2,800 per crack
Exterior excavation to seal one crack (6–8 ft deep)	$3,500 – $8,500 per crack
Exterior waterproofing, full wall section	$8,000 – $25,000+
Tie-rod hole sealing	$75 – $150 each

Additional cracks fixed on the same visit usually cost less than the first. Opening and restoring drywall in a finished basement adds to the price.

Questions to ask any contractor

Will you inject with polyurethane or epoxy, and why for my crack?
Is the quote per crack or per foot, and does it include drywall removal and restoration?
What's the warranty, is it in writing, and does it transfer if I sell?
Are you insured and covered by WSIB?
If it leaks again, what happens?

Crack repair across Durham Region

We connect homeowners in Pickering, Ajax, Whitby (including Brooklin), Oshawa and Clarington (Bowmanville, Courtice and Newcastle) with a local foundation contractor who works in their town. Older homes near the downtowns of Oshawa, Whitby and Bowmanville often have block or early poured foundations, where cracks and leaks are more common. Newer subdivisions see shrinkage cracks and leaks at tie-rod holes within the first years.

Get matched with a contractor

Common questions

Should I worry about a hairline crack in my basement wall?

A thin, vertical crack that's dry and isn't getting wider is usually shrinkage from when the concrete cured. It's cosmetic. Mark the ends with a pencil and the date, and check again in a few months. If it grows, gets damp or leaks, have it looked at.

What kind of crack is serious?

Horizontal cracks partway up the wall, stair-step cracks in block foundations, cracks wider than about 6 mm (1/4"), cracks where one side sits higher than the other, or any wall that bows inward. These can mean soil pressure or settlement, and they need an assessment, often by a structural engineer, before anything is sealed.

Can I fix a foundation crack myself?

DIY kits can seal a dry cosmetic crack. For a crack that leaks, most homeowners hire a pro: injection has to fill the crack through the full wall thickness, and a failed patch makes the proper repair harder and pricier.

Does crack repair need a building permit in Durham?

Injecting a crack from inside generally doesn't need a permit. Structural repairs, underpinning and footing work usually do. Check with your town's building department (Pickering, Ajax, Whitby, Oshawa or Clarington) or ask the contractor to confirm.

Is foundation crack repair covered by home insurance?

Usually not. Most policies exclude cracks from settlement, shrinkage or wear. Damage from a sudden event may be covered. Call your insurer before the repair and keep photos of the crack and any water damage.

How long does a crack repair last?

A properly done interior injection is meant to be permanent, and many contractors warranty it for the life of the home or a long fixed term. Ask whether the warranty transfers if you sell.

Tell us what you're seeing

Free, no obligation. We pass your details to one local foundation contractor who calls you back to book an assessment and give you a written quote.