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“The sweating house”
Mould at home: why it appears and how to get rid of it
Mould is a symptom, not the cause. It grows when the humidity at the surface stays above ~80% for days. Cleaning without fixing the cause only delays its return.
Signs
- Black or green spots
- Musty smell
- Cold corners, behind wardrobes, bathrooms
- Comes back weeks after cleaning
behind furniture
Most common causes
Almost always condensation. Sometimes an old leak that keeps the wall damp.
Treatments and observed prices
- Cleaning with diluted bleach (do it yourself)€5–15
- Professional mould cleaningfrom €48
- Anti-mould paint€25–60/tin
Sources: Habitissimo, Zaask, cume.pt, customer reports. Collected on 02.10.2026.
Read next
Mould in the bedroom: why it appears and how to get rid of it- Damp and health: what the evidence says (without scaremongering)
Anti-mould paint: when it helps and when it hides the problem
Written by the humidade.pt team · Reviewed by a civil engineer (to be confirmed) · Updated October 2026