Cracks in the Foundation Wall: Who Should You Call?
Urgency: Plan aheadUpdated 2026-08-31
Short answer
Thin vertical hairline cracks in poured concrete are usually shrinkage and only matter if they leak. Horizontal cracks, stair-step cracks in block, or any crack wider than roughly 6 mm suggest movement and should be assessed by a structural engineer before a contractor quotes repairs.
Who to call: A foundation or waterproofing contractor for leaking cracks; a structural engineer if the crack is horizontal or wider than about 6 mm.
What to do right now
- 1Photograph the crack next to a ruler or coin so you can compare it later.
- 2Pencil the date at each end of the crack to track whether it is growing.
- 3Check exterior grading and downspouts — most foundation issues start with water sitting against the wall.
- 4Note whether the crack is damp, and whether it changes after heavy rain.
Most likely causes
- Concrete shrinkage
- Normal curing cracks in the first year or two after a pour. Usually harmless.
- Hydrostatic pressure
- Saturated soil pushing on the wall — common in GTA clay soils after wet springs.
- Frost heave
- Freeze-thaw cycling lifting footings and porches.
- Settlement
- Uneven soil bearing, often showing as stair-step cracks in block foundations.
What it typically costs in the GTA
$400–$900 for interior epoxy or polyurethane crack injection. $3,000–$10,000 for exterior excavation and waterproofing of one wall. $500–$1,200 for a structural engineer's assessment letter.
Ranges are typical market pricing for the Greater Toronto Area and vary with access, age of the home, and time of year. Always get the scope in writing before work starts.
Which cracks are actually serious
Direction tells you most of it. Vertical and diagonal hairlines are typically shrinkage or minor settlement. Horizontal cracks — particularly with inward bowing — indicate lateral soil pressure and are the ones to take seriously.
- Hairline vertical, dry: monitor.
- Vertical, leaking: injection and drainage correction.
- Stair-step in block: settlement, get it assessed.
- Horizontal with bowing: structural, engineer first.
Get the engineer before the contractor
For anything that looks structural, an independent engineer's report gives you a scope that contractors bid against — instead of each contractor proposing a different and conveniently expensive solution.
Get the right pro on it
Describe the problem in your own words. We’ll work out which trade you need and connect you with suitable local pros. Free, no obligation.
Frequently asked questions
- Are foundation cracks normal in new homes?
- Small shrinkage cracks are extremely common in the first couple of years and are usually covered under Tarion warranty if they leak.
- Can I seal a foundation crack myself?
- Hydraulic cement patches a dry cosmetic crack. A leaking crack needs proper injection from a contractor to seal the full wall thickness.
- Will a crack fail a home inspection?
- Inspectors flag them and often recommend a specialist review, which can affect negotiations. Documentation of a professional repair helps.