IN SHORT
- A musty, earthy smell is often the first sign, before anything is visible.
- Black, green, white, grey and brown are the most common colours indoors.
- Colour can't confirm the type. Only laboratory analysis can.
- Whatever the type, moisture is what lets it grow.
How to spot mould
Often your nose notices mould before your eyes do. A musty, earthy smell, a bit like damp soil or old timber, is one of the first signs. When it is visible, mould can look fuzzy, or appear as flat, discoloured patches. Unlike dirt or dust, it usually spreads outward in rough circles.
The most common colours in Australian homes are black, green, white, grey and brown. Pink, orange and yellow growth turns up too.
Why Australian homes are prone to mould
Our climate and the way many homes are built both play a part. Humid summers, wet years like the recent La Niña seasons and subfloors that hold damp air all give mould the moisture it needs. Places we often see it include:
- Behind and around bathroom tiles
- Under kitchen and laundry sinks
- Roof spaces and poorly ventilated subfloors
- Behind furniture pushed against cold external walls
The most common types
Several groups of mould (genera) are regularly found indoors:
- Aspergillus: very common, often powdery once mature, in shades of green, black or brown.
- Penicillium: blue-green to white and fuzzy, often on water-damaged materials and behind wallpaper.
- Cladosporium: dark green to black with a velvety texture, common on window frames and painted surfaces.
- Stachybotrys: greenish-black and slimy, usually where materials such as plasterboard have stayed wet for a long time.
- Chaetomium: brown to black with a strong musty smell, also linked to materials that have been wet for an extended period.
Colour can't confirm the type. A black patch could be Cladosporium or Stachybotrys, and the two look very different under a microscope. When the exact type matters, a qualified professional takes a sample for laboratory analysis.
What to do if you find mould
Start with the moisture. Whatever type of mould it is, it needs water to grow, so a patch tells you something in your home is staying damp. Until that changes, mould can keep coming back.
Avoid scrubbing or dry brushing the area, which can release spores into the air, and keep fans pointed away from it. If the patch is larger than about one square metre, keeps returning or sits on a porous material such as plasterboard, have it assessed.
WHERE DRYSAFE FITS
Our assessment is visual, with moisture and humidity readings, so you know what you're dealing with before any work starts. Identifying a species takes a laboratory.