Before you put a sign on the lawn, it’s worth doing your own walk-through for mold — before a buyer’s inspector does it for you. In BC, sellers are generally expected to disclose known moisture or mold problems on the Property Disclosure Statement, and nothing stalls a deal faster than a surprise during the buyer’s inspection period. A half-hour walk-through with a flashlight can tell you whether you’re dealing with a quick fix or something that needs to be resolved — and disclosed — before you list.
Why this matters more at listing time
Mold found by your own eyes, on your own schedule, is a problem you control. Mold found by a buyer’s inspector, after you’ve already accepted an offer, is a problem that controls you — it can mean a renegotiated price, a delayed closing, or a buyer walking away entirely. Checking ahead of time gives you the choice of fixing it quietly, pricing around it, or disclosing it on your own terms instead of reacting to someone else’s report.
The walk-through: where to look
Mold needs moisture, so it shows up in predictable places. Go room by room with a flashlight and check the following areas specifically.
Windows and window sills
Condensation on older or poorly sealed windows is one of the most common sources of small mold patches. Check the sill, the bottom corners of the frame, and the wall just below the window for black speckling, soft or discoloured paint, and a musty smell. Older single-pane or poorly sealed windows in bedrooms and basements are the usual culprits.
Sink cabinets (kitchen and bathroom)
Open every cabinet under a sink and feel around the supply lines, the drain trap, and the cabinet floor. A slow leak here can go unnoticed for months because the smell is contained and the staining is hidden at the back of the cabinet. Look for swollen particleboard, dark staining, or a musty smell as soon as you open the door.
Bathrooms
Check the grout and caulking around the tub and shower, the ceiling directly above the shower (especially if there’s no exhaust fan or it’s rarely used), and behind the toilet. A weak or missing exhaust fan is one of the most common root causes of recurring bathroom mold, so it’s worth checking whether yours actually vents outside rather than into the attic.
Basements and storage areas
Basements are the highest-risk area in most homes, especially in older construction or homes without proper perimeter drainage. Check the base of foundation walls, around window wells, behind stored boxes or furniture pushed against exterior walls, and inside any storage areas that don’t get much airflow. A musty smell that’s stronger in the basement than anywhere else in the house is a sign something’s there even if you can’t see it yet.
Closets
Closets on exterior walls, especially in bedrooms that don’t get much heat or air circulation, can develop mold on the back wall behind stored items. Pull everything off the floor and away from the back wall and check for discoloration or a musty smell, particularly in closets that share a wall with a bathroom or sit above an unheated garage.
Attics
If you have safe access, check the attic for dark staining on the underside of the roof sheathing, especially near bathroom and kitchen exhaust vents — a common problem is an exhaust fan that was never properly ducted all the way outside. Also check for adequate insulation and any signs of roof leaks around chimneys, vents, or skylights. If you can’t access the attic safely yourself, this is one area worth having a professional check as part of a broader assessment.
What counts as a red flag
Not everything you find is cause for alarm, but a few signs mean it’s worth taking seriously rather than painting over:
- A musty smell in a room with no visible staining — this usually means the mold is behind a wall, under flooring, or in a space you can’t see directly.
- Staining that keeps returning after you’ve cleaned it before.
- Soft, swollen, or crumbling drywall or particleboard.
- Discoloration that follows a water stain, past leak, or flood.
- Any mold near an HVAC return, since that can spread spores through the whole house.
What to do if you find mold
Health Canada’s guidance is that small patches — three or fewer, with a combined area under about 1 square metre, roughly the size of a bathroom vanity — can usually be cleaned by a homeowner if the underlying moisture source is also fixed. If what you’ve found is larger than that, keeps coming back, followed a flood or significant water event, or you simply can’t tell how far it extends, that’s when it makes sense to bring in a professional rather than guess.
Before you list, a professional assessment does two things for you: it tells you exactly what you’re dealing with so you can fix it properly instead of just cosmetically, and it gives you a clean report you can point to if a buyer’s inspector raises a concern later. That’s often worth more than the cost of the inspection itself, especially if it heads off a renegotiation during your subject-removal period.
If you’d like a second set of eyes before you list — or lab confirmation on something you’re not sure about — a pre-listing mold inspection can give you a clear picture and a report in hand before your first showing. Our assessments are discreet, with unmarked service vehicles, and lab results typically come back within 4 business days.