Mould vs mildew — what's the actual difference?
Mildew is a type of mould. Both are fungi, both grow in damp conditions, and both leave the same musty smell. The differences are practical: mildew is the flat, powdery white or grey film that sits on the surface of a damp wall or fabric. Mould is the thicker, fuzzier, often dark green or black growth that pushes its roots into the material underneath.
How to tell them apart at a glance
| Mildew | Mould | |
|---|---|---|
| Look | Flat, powdery, white/grey/yellowish | Fuzzy or slimy, often green, black, or dark brown |
| Surface | Sits on top of the material | Grows into the material |
| Common locations | Bathroom tiles, shower curtains, leather | Walls, ceilings, behind furniture, wardrobes |
| How easily it wipes off | Usually wipes away with a damp cloth | Leaves staining and roots even after cleaning |
| Health impact | Mild irritation, sneezing | Can cause more serious respiratory issues over time |
Why mildew appears first
Mildew is the early warning. It grows fast on flat damp surfaces — a shower screen, a window sill, a tile grout line — and it tells you the conditions are right for full mould to follow. Most household mould has been mildew first. Catching it at the mildew stage is the difference between a five-minute wipe and a real cleaning project.
How to treat mildew
- Wipe it off with a damp cloth. White vinegar diluted one-to-four with water works as well as commercial sprays for surface mildew.
- Dry the area thoroughly. A microfibre cloth and an open window for an hour will do it.
- Fix the moisture source. Air the room daily, install a vent, run the bathroom fan longer, or add a passive moisture absorber to the nearest closed space.
How to treat mould (and when to call someone)
For small patches of surface mould on hard surfaces (less than about A4 size), the same vinegar solution and a stiff brush will handle it. Wear gloves and open a window. For mould on porous surfaces — plaster, plasterboard, carpet — or for any area larger than A4, call a professional mould remediation service. The roots embed too deep for surface cleaning.
How to stop either one from coming back
Mildew and mould both come back when the underlying humidity stays the same. Permanent prevention is not in the cleaning product — it is in the moisture control. Ventilate, declutter so air can move, and add a passive absorber to any closed cupboard, wardrobe or stored space that does not dry out on its own.
