IN SHORT
- Active growth often looks fuzzy. Dormant growth looks dry and powdery.
- A musty, earthy smell is a sign even when nothing is visible.
- Mould is often mistaken for dirt or soot, but it tends to return after cleaning.
- Patches larger than about one square metre are worth a professional look.
What mould looks like
Mould takes many forms. Active growth often looks fluffy or fuzzy, with fine strands spreading across the surface. Dormant growth tends to look dry and powdery. Common colours include black, green, grey, white and brown, with occasional pink or yellow.
Some dark moulds look greenish-black and slimy, which usually means the material underneath has been wet for a long time.
Mould, dirt or soot?
Mould is easy to mistake for dirt or soot, particularly near windows, air vents and fireplaces. Signs that point to mould: it feels slightly raised, it grows in spreading spots or circles, and it comes back after cleaning if the moisture remains.
Where to look
- Bathrooms: grout lines, behind tiles and around shower screens.
- Kitchens: under sinks and behind dishwashers, where slow leaks go unnoticed.
- Roof spaces: blocked gutters or small roof leaks can go unseen for months.
- External walls: furniture pushed against cold walls can trap condensation behind it.
- Air conditioning: drip trays and ducts, if they aren't maintained.
What to do if you spot it
If you notice a musty, earthy smell, or the patches are larger than about one square metre, it's time to have it looked at. Avoid brushing or scrubbing, which can release spores into the air, and keep fans away from it.
Mould needs moisture, so the moisture needs attention too. Keeping indoor humidity between 30% and 50%, ventilating well and checking your home after heavy rain all help.
WHERE DRYSAFE FITS
Every DrySafe job starts with a visual mould assessment and moisture and humidity readings, and ends with a written works report with before-and-after photos.