Glossary · Health & indoor air
Mould
Also called: moulds · black mould
Fungi that grow on damp surfaces indoors; they can damage materials and affect health, and moisture is always the root cause.
What it means
Mould needs moisture, so it appears where there are leaks, condensation or high relative humidity: basements, bathrooms, window frames, attics and cold walls behind furniture. A musty smell can be a sign even when you can't see it. Small areas can usually be cleaned by homeowners; large or recurring growth needs a professional and a fix for the moisture source.
Why it matters in an audit
Auditors look for mould and moisture because sealing or insulating over a damp area can make it worse, so moisture problems are fixed first.
Typical numbers
Reference values with their sources. Your energy advisor’s report gives the figure for your own house.
| What | Value | Source |
|---|---|---|
| Size categories (Health Canada) | Small: up to 3 patches, each under 1 m²; medium: more than 3 patches or patches of 1–3 m²; extensive: a patch over 3 m² (consider a professional) | canada.ca ↗ |
| Humidity to discourage mould (Health Canada) | 30%–50% | canada.ca ↗ |
In Canada
Health Canada says small and medium areas can generally be cleaned yourself, and to get professional help for extensive or recurring mould.