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Basement floor heaving in Winnipeg

Basement floor heave is one of the most common foundation problems in Winnipeg. In many homes, the basement slab sits directly on the clay, and when that clay swells, it pushes the floor up, usually most in the middle.

Signs your floor is heaving

• A hump or high point near the middle of the basement floor.
• Long cracks across the slab, sometimes with one side higher than the other.
• Basement doors that stick or no longer close.
• Partition walls pushing up into the floor joists, which can crack drywall and make floors upstairs bulge.

Why it happens

The clay under the slab swells when it takes on moisture, from a leaking pipe, a high water table, poor drainage, or simply seasonal change. Because the walls and footings are anchored differently from the floor, the floor rises while the rest of the house stays put.

How it's usually handled

• Adjusting partition walls. Many basement walls are built to "float" with a gap at the top or bottom so floor movement doesn't push into the house. Fixing or adding that gap is a common first step.
• Fixing the moisture source. Leaking plumbing under the floor or drainage problems can drive the swelling.
• A new floor. For severe heave, contractors may remove the slab and some clay and pour a new floor, sometimes a structural slab supported on piles with a void space underneath so the clay can move without lifting it.

Floor lifting or cracking? Use the form on this page, choose "Basement floor heaving or cracking", and tell us if you're planning to finish the basement. A local contractor will follow up.

Common questions