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Basement Mould: Surface Mildew or Water Infiltration?
Tell condensation from leaks, fix the moisture, then deal with the mould.
Basements in Canada are prone to moisture: cold walls, high groundwater, spring thaw. Mould is often the visible sign of a moisture problem.
Surface mildew versus deeper problems
Light spotting on a cold wall or window frame often comes from condensation. Mould behind drywall, along the floor or around cracks usually points to water getting in.
Signs of water infiltration
- White powdery efflorescence on concrete
- Water stains at the base of walls
- Damp carpet or flooring
- Musty smell that doesn't go away
- Cracks with staining
Fixing the moisture source
Check grading, downspouts and eavestroughs first. Persistent leaks may need foundation crack repair, waterproofing or drainage work.
Cleanup and remediation
Health Canada advises that small areas can usually be cleaned by homeowners, while larger areas need professional help. Remediation contractors contain the area, remove affected materials and dry the space.
Common questions
No. Clean or remove it and fix the moisture source.
It helps with humidity but won't stop water coming through walls.
A waterproofing contractor for leaks, and a remediation contractor for large mould areas.