When damp isn't a dehumidifier problem
A dehumidifier lowers humidity in the air. It doesn't stop water getting into a building.
Signs to look into the cause first
- Wet or damp patches on walls or ceilings, especially after rain.
- Peeling paint or plaster, or a tide mark.
- Mould that returns soon after cleaning.
- Damp after a leak, or near plumbing.
These can point to a leak, rising or penetrating damp, or a failed gutter or roof, which need to be fixed at the source. A dehumidifier can still help with condensation and drying laundry, but it won't solve those.
Condensation
If the damp is mostly condensation on windows and cold walls, a dehumidifier plus ventilation and heating can help. Our sizer is aimed at this case.
If you rent
Social landlords in England have had to follow Awaab's Law since late October 2025, which sets time limits for investigating and fixing hazards such as damp and mould. A government consultation on extending similar rules to the private rented sector closes on 18 December 2026. Check gov.uk for the latest, as this may change. Your local council or Shelter can advise on your rights.
Sources: gov.uk guidance on Awaab's Law and the private rented sector consultation. This is general information, not legal or building advice.