Updated 2 November 2026 · By Diego Gómez

How to get rid of mould on walls (and stop it coming back)

Step-by-step guide to removing black mould from walls, ceilings and window frames in a UK home, and the three things that stop it returning.

Black mould in corners, behind wardrobes and around window frames is one of the most common problems in British homes, especially in winter. Cleaning it is the easy part; stopping it coming back means lowering the humidity.

1. Clean it safely

  • Open the window and wear rubber gloves and a mask.
  • For small patches on painted walls or tiles, use a mould spray or diluted bleach (about 1 part bleach to 4 parts water). Never mix bleach with other cleaners.
  • Wipe, don't brush: brushing spreads the spores.
  • Dry the area completely afterwards.

If the mould covers more than about a square metre, keeps coming back after cleaning, or is linked to a leak or rising damp, it needs a professional or your landlord. See our guide for renters.

2. Find out how damp your home is

A cheap hygrometer tells you the relative humidity. Above 60% for long periods, mould grows. Check first thing in the morning, when it's highest.

3. Lower the humidity

  • Ventilate briefly but fully: open windows wide for 10 minutes a day rather than leaving one on the latch all day.
  • Use extractor fans when cooking and showering, and keep doors closed.
  • Don't dry laundry in the living room. One wash load can release a couple of litres of water into the air. Use a small room with a dehumidifier.
  • Use a dehumidifier sized for your home: see what size you need.
  • Keep rooms evenly warm. Cold walls attract condensation; switching heating off completely in some rooms often makes mould worse.

Recommended

Best for most homes

Pro Breeze OmniDry 12L

  • 12 L/day
  • up to 15 m²
  • 2 L

The best-selling dehumidifier on Amazon UK right now: 12 litres a day, automatic humidity sensor, laundry mode and a drain hose option.

Check price
For cold rooms

EcoAir DD2 Simple (desiccant)

  • 9 L/day
  • 1 °C
  • 3 L

A light desiccant dehumidifier that keeps working in cold, unheated rooms down to 1 °C, where compressor models struggle.

Check price
Measure first

ThermoPro TP49 hygrometer (4-pack)

  • temperature and humidity
  • 4
  • AAA

Cheap digital hygrometers with a comfort-level face.

Check price

Affiliate links: if you buy, Amazon pays us a small commission at no extra cost to you. More info

FAQs

Is black mould dangerous?

Mould can irritate the lungs and worsen asthma and allergies, especially for children, older people and anyone with breathing problems. The NHS advises dealing with damp and mould rather than living with it.

Does bleach kill mould?

On hard, non-porous surfaces it removes the visible staining and surface mould. On porous surfaces like plasterboard, mould can grow back from within, which is why reducing humidity matters more than the cleaning product.

Related guides