Can I repair my own foundation crack in New Brunswick?

Whether you can repair a foundation crack yourself depends entirely on the type, cause, and severity of the crack. Some foundation cracks are simple cosmetic issues with low-risk DIY solutions; others are symptoms of active structural movement that require professional engineering assessment before any repair is attempted.

First, understand what type of crack you have:

Hairline cracks (under 1 mm wide) in poured concrete foundations are extremely common and are typically caused by normal concrete shrinkage during curing. They are usually vertical or diagonal in the upper portion of the wall, stable (not growing), and do not leak. If the crack has been stable for years and has no water infiltration, this is the lowest-risk DIY repair: clean the crack, allow it to dry, and fill with a concrete crack filler or polyurethane injection kit available at NB building supply stores. Monitor it — if it continues to grow, something is causing movement.

Horizontal cracks in a foundation wall are a serious warning sign. Horizontal cracking indicates the wall is bending inward under lateral soil pressure — a structural problem. This is not a DIY repair under any circumstances. A structural engineer must assess the wall before any repair is attempted. The cause — poor drainage, high water table, frost pressure, excessive surcharge — must be addressed or the repair is futile.

Stair-step cracks in masonry (block or stone foundations) indicate differential settlement — the foundation is sinking unevenly. In NB's frost-active soils, this can happen if a footing was originally installed above the frost line. Settlement cracks require professional assessment.

Actively leaking cracks — where water is seeping or running through — indicate hydrostatic pressure from groundwater. Hydraulic cement can be used for a quick DIY patch to stop active water flow (it sets in minutes), but it does not address the water source. The long-term fix requires exterior waterproofing, drainage improvement, or an interior drainage system — all professional work.

DIY repair is reasonable for: stable, hairline, dry cracks in poured foundations that have not changed in size for at least one full NB frost cycle. Polyurethane injection kits from hardware stores work well for this application.

Always call a professional for: horizontal cracks, stair-step cracks, cracks wider than 5 mm, cracks that are growing, any crack accompanied by water infiltration, or any crack in a foundation wall where you are unsure of the cause.

Before any foundation repair, document the crack with photos and a pencil line marking the ends — monitoring crack growth over time tells you whether the problem is stable or active. New Brunswick Concrete can match you with contractors who specialize in foundation assessment and repair across New Brunswick.