How Do I Spot Mold Before the Inspector Does?

Mould shows up first in the places a home inspector checks last: behind baseboards, under sink cabinets, around old window frames and in attic insulation. Walk those spots yourself before you pay $400 to $600 for an inspection, since CMHC's own homeowner guidance points to the same moisture-prone areas an inspector will flag.

A musty smell is usually the first sign, arriving well before you can see anything on a wall or ceiling. Follow it. In a Saskatoon house, the likeliest sources are a bathroom fan that vents into the attic instead of outside, a basement that holds humidity through spring runoff, a roof or flashing leak above an exterior wall, and condensation on older single-pane windows during the deep cold of a Saskatoon winter. Any one of those, left unaddressed, gives mould exactly what it needs, which is a steady moisture source and a surface to grow on.

Check the same spots a Canada Mortgage and Housing Corporation moisture guide tells inspectors to check. Pull back baseboards in the basement and look for staining or a powdery white residue on the concrete, which points to water finding its way in rather than condensation on the surface. Open the cabinet under every sink and run a hand along the underside of the counter and the back of the cabinet wall. Look at the drywall directly above and below every window for soft spots or discolouration, and check the attic hatch for frost or dark staining on the underside of the roof deck, both signs that warm, moist household air is escaping upward and condensing where it hits cold sheathing.

If you find something, the fix matters more than the discovery. A small patch of surface mould on drywall is a cleaning and moisture-source problem. Staining that returns after cleaning, or mould behind a wall you can smell but not see, is a moisture problem first and a mould problem second, and painting over it without fixing the source only hides it until the next inspection finds it again. A licensed home inspector will use a moisture meter and a thermal camera to find what a walk-through misses, which is exactly why doing your own check first is useful. It tells you what to ask about, and gives you time to fix a small problem before it becomes a line item a buyer's inspector uses to negotiate the price down.

For a seller, this matters most when the issue sits behind a finish that has already been repaired. A basement that was remediated and refinished five years ago will not show up as a mould concern to an inspector or to an online valuation tool, but the repair itself, and the reason behind it, is exactly the kind of history a hand-reviewed valuation accounts for. Get your hand-reviewed valuation from Joel Dyck.