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    Ontario home illustrating water protection from roof leaks through foundation and drainage — Waterproof Ontario.

    Why is water coming in where the wall meets the floor?

    The cove joint is where hydrostatic pressure shows up when perimeter drainage cannot relieve it.

    Water at the joint where a basement wall meets the floor usually means pressure under the slab is pushing water through the cove, the cold joint that was never waterproofed as a seal. Failed or clogged weeping tile, a high water table, and poor exterior drainage are the usual causes. A wall crack can leak nearby, but a wet seam all along the floor is a drainage problem, not a paint problem.

    Where the water shows up

    What you seeLikely cause
    Seam wet after rain or thawPerimeter drain or grading cannot relieve pressure
    One corner onlyA low spot, downspout, or window well feeding that wall
    Floor damp, walls dryWater rising at the cove or through the slab, not a wall crack
    Efflorescence along the seamRepeated wetting and drying at the joint

    What to do now

    Mark the wet length of the joint and whether it follows rain, thaw, or stays damp. Do not caulk the seam and finish over it. That traps water in the wall.

    When to call a contractor

    Call when the seam wets more than once, when you smell must, or before you install flooring. Interior drainage is often the practical fix when the outside cannot be dug; exterior work is the fix when the drain itself has failed and access exists.

    Start with the provincial guide water in the basement, then the Ontario cost hub.

    Local basement waterproofing guides

    Can I seal the wall-floor joint from the inside?

    A surface seal at the cove usually fails under pressure. Interior drainage collects water at that joint and sends it to a sump. Exterior repair replaces the drain and membrane when the lot allows a dig.

    Does a wet cove joint mean the foundation is failing?

    Not by itself. It means water pressure at the cold joint. Bowing, horizontal cracks, or displacement are the structural signs that need a foundation assessment, not only waterproofing.

    Resources & guides

    Practical articles on moisture, foundations, and keeping water out of Ontario homes.

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