How to Remove Mildew Smell from Your Home
Mildew odour — that distinctive musty, damp smell — is one of the hardest smells to eliminate from a Toronto home. It's caused by mould and mildew growth, and masking it with air freshener doesn't work. You need to find the source and treat it. Here's how.
Find the Source First
Mildew odour means mould is growing somewhere. Common sources in Toronto homes:
- Bathroom: Behind caulk, in grout, on the ceiling above the shower, or in the exhaust fan housing
- Basement: Behind drywall, on exposed concrete, on stored cardboard or fabric
- Under sinks: On the cabinet floor from a slow drip
- Washing machine: Especially front-loaders — the door gasket and drum
- Refrigerator drip pan: The pan beneath the fridge that most people never check
- Crawl spaces and attic: Mould here spreads odour throughout the HVAC system
- Carpets: After any flooding or persistent humidity
Follow your nose — the smell is strongest at the source. If you can't find it, check every under-sink cabinet and look for any staining on walls or ceilings.
Treating Mould on Hard Surfaces
Once you find visible mould:
- Non-porous surfaces (tile, grout, glass, metal): Spray with undiluted white vinegar, let sit 1 hour, scrub and rinse. For severe growth: spray with 3% hydrogen peroxide (let sit 10 minutes) or a 1:10 bleach-to-water solution. Rinse thoroughly.
- Painted drywall with surface mould: Use a 1:10 bleach solution and ventilate well. If the mould has penetrated the drywall, the section needs to be cut out and replaced — surface treatment won't address embedded growth.
- Caulk: If mould has grown into the caulk, the caulk must be removed and replaced — no surface treatment kills mould that's inside the caulk bead.
Eliminating Residual Odour (After Source Is Treated)
Once the mould is gone, residual odour molecules remain in fabrics, carpets, and air. Treatments:
- Baking soda: Place open boxes in affected areas — absorbs odour molecules over days
- White vinegar: Place small bowls around the room — the vinegar neutralizes airborne mould-related odours as it evaporates
- Activated charcoal bags: More effective than baking soda and reusable — available at hardware stores
- HEPA air purifier: Runs the air through a filter that captures mould spores — the most thorough solution for pervasive odour
- Fresh air: On a dry Toronto day, open all windows and use fans to exchange the air
Preventing Mildew Smell
- Run bathroom exhaust fan during and 20 minutes after every shower
- Fix drips and leaks immediately — moisture within 24–48 hours starts mould growth
- Keep basement humidity below 50% — use a dehumidifier from May through October in Toronto
- Leave washing machine door open between uses
- Never store damp towels or clothing in a closed space
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