Mould is a symptom of moisture, not of dirt
People scrub the patches, the patches come back, and the conclusion is that a stronger product is needed. In reality mould grows where moisture is constant and air does not move. Until the source of moisture is removed, any treatment is temporary cosmetics.
So the order is: find the source, remove it, dry the space, and only then treat the surface. The reverse order produces exactly the result everyone observes.
Where to look for the source
| Place | What to check |
|---|---|
| Bathroom and kitchen | Ventilation, extraction, drying after showers, joints |
| Windows and reveals | Condensation, cold bridging, the handle’s seasonal setting |
| Walls behind furniture | No circulation, a cold wall |
| Pipes and risers | Condensation, drips, hidden leaks |
| Basement and roof | Ground and top floors suffer more often |
| Drying laundry indoors | Litres of water into the air per load |
Test the draw with a sheet of paper at the vent: if it does not hold, the ventilation is not working, and that is the first thing to fix.
What helps without renovation
Regular short bursts of ventilation, a working extractor, furniture pulled away from walls, drying wet areas, drying laundry with a window open or somewhere else. A dehumidifier solves it where the humidity is persistently high.
A warm wall does not produce condensation, so cold corners need insulation as well as airing — but that is a separate job.
Treating the surface
Only after the moisture is gone and the space is dry. Porous materials that absorbed the growth deeply usually have to be removed: wallpaper, some plaster, silicone joints. Work in gloves and a mask with ventilation, never mix products and follow the instructions for whatever you use.
When this is not a household task
A large area, repeated regrowth in the same place, a smell with no visible patches, several rooms affected, or allergies and breathing problems in the household — those call for professionals rather than a third round of scrubbing.
When the problem is solved
The moisture source is found and removed, the ventilation works, the space is dried, affected porous materials are gone, the surface is treated as instructed, and the home now has a routine in which moisture does not build up again.
