Buying Guide
How to Stop Condensation in a Bathroom UK 2026
Updated August 2026
The bathroom is where most household damp starts. A single shower puts more moisture into the air than a whole day of cooking, and if it doesn't leave the room it ends up as black spotting on the sealant, peeling paint and mould on the ceiling. Here is the order to fix it in — extraction first, habits second, products third.
Quick answer
Our top pick: Envirovent SIL100T extractor fan + humidity monitoring
£10 – £80 on Amazon
Run an extractor fan with a 15–20 minute overrun during and after every shower, keep the door shut while it clears, and hold the room between 40–60% RH. If you can't fit a fan, use a small dehumidifier and a moisture absorber, and squeegee the tiles.
Check Price on Amazon →Why bathrooms steam up so badly
Three things combine. First, volume: a hot shower releases roughly 0.5–1 litre of water vapour in ten minutes. Second, room size: a typical UK bathroom is under 10m³, so humidity hits 100% almost instantly. Third, cold surfaces — tiles, mirrors, an uninsulated external wall and a cold ceiling void above.
Moisture always condenses on the coldest surface in the room. That's why the mould appears in the same three places every time: the ceiling above the shower, the silicone at the bottom of the tiles, and the corner on the external wall.
7 fixes that actually stop bathroom condensation
- Fit or upgrade the extractor fan. You want at least 15 litres/second for a bathroom, with an overrun timer or humidity sensor. A fan that stops the instant you flick the light off does maybe half the job.
- Run it for 15–20 minutes after the shower, door closed. This is the single highest-impact habit change and it costs about 1p a day.
- Squeegee the tiles and screen. Thirty seconds removes several hundred millilitres of water that would otherwise evaporate back into the room.
- Shower cooler and shorter. Dropping the temperature a couple of degrees measurably cuts the amount of vapour produced.
- Keep the room gently warm. A bathroom that never drops below about 16°C has warmer surfaces, so less moisture condenses in the first place.
- Hang towels somewhere ventilated. Wet towels left on a rail in a closed bathroom re-release all that water into the room over the following hours.
- Monitor humidity. A £5 hygrometer tells you whether the fan is actually clearing the room. Target under 60% RH within half an hour of a shower.
Getting condensation on the windows elsewhere in the house too? See the full window condensation guide →
Products that fix bathroom condensation
Envirovent SIL100T Silent 100mm Extractor Fan with Timer
Noise is why people switch fans off. This one is quiet enough that the overrun timer never annoys anyone, which is exactly why it works.
Pros
- Genuinely quiet — people actually leave it running
- Adjustable overrun timer
- Strong extraction for a 100mm unit
- Long service life
Cons
- Needs an electrician if there's no existing fan
- Dearer than basic fans
Who it's for: The permanent fix in any bathroom you own
Check Price on Amazon UK →XIIW 100mm Extractor Fan with Humidity Sensor and Timer
If the problem is behavioural rather than mechanical, a humidity sensor solves it. It reacts to the steam whether anyone thought about it or not.
Pros
- Starts itself when humidity rises
- No reliance on anyone remembering
- Timer plus sensor in one unit
Cons
- Sensor threshold needs tuning
- Louder than the Envirovent
Who it's for: Shared houses and families where nobody uses the fan switch
Check Price on Amazon UK →Devola 100mm Standard Bathroom Extractor Fan
A working cheap fan beats a broken good one. If yours has died, this gets extraction back for under £30.
Pros
- Cheap direct replacement
- Simple fit into an existing 100mm duct
- Decent airflow for the price
Cons
- Noisier
- No overrun on the basic version
Who it's for: Swapping out a dead fan on a budget
Check Price on Amazon UK →DOOMAY Mini Hygrometer
Buy one before you spend anything else. It turns 'the bathroom feels damp' into a number you can act on.
Pros
- Shows whether the fan is doing its job
- Tiny and stick-anywhere
- Cheap enough for every room
Cons
- Basic accuracy
- No logging
Who it's for: Checking humidity drops back under 60% after a shower
Check Price on Amazon UK →UniBond AERO 360 Moisture Absorber
A supporting act, not a solution. Useful between showers in a small en-suite, but it won't replace extraction.
Pros
- No electricity or fitting needed
- Silent
- Good for windowless en-suites
Cons
- Can't cope with shower steam alone
- Ongoing refill cost
Who it's for: Topping up ventilation in a small or rented bathroom
Check Price on Amazon UK →If you rent or can't fit an extractor fan
- Open the window fully for 10 minutes after every shower, even in winter — short and wide beats permanently ajar.
- Keep the bathroom door shut while the room clears so moisture doesn't spread into bedrooms.
- Squeegee the screen, tiles and any wet surfaces before you leave.
- Run a small dehumidifier in the room for an hour after showering, or in the hallway outside.
- Place a moisture absorber tub on the windowsill and replace the tabs every 8–10 weeks.
- Report a broken or missing extractor fan to your landlord in writing — ventilation is their responsibility.
Landlord not acting? Know your rights on damp and mould →
Removing the mould that's already there
- Open the window and wear gloves and a mask — disturbing mould releases spores.
- Use a proper fungicidal mould remover, not household bleach. Bleach lightens the stain but leaves the roots in porous sealant.
- Leave it on for the full dwell time stated on the bottle before wiping.
- Black silicone that stays stained after treatment needs cutting out and replacing — the mould is inside it.
- Repaint ceilings with an anti-mould emulsion once the surface is fully dry.
- Fix the ventilation at the same time, or it returns within a couple of months.
Buying advice
Extraction first, everything else second
Tip
The overrun timer is the whole trick
Warning
Don't seal the bathroom up
Frequently asked questions
Bundle
Bathroom Damp Control Kit — Under £80
- Envirovent SIL100T extractor fan£55Amazon →
- DOOMAY mini hygrometer£6Amazon →
- UniBond AERO 360 moisture absorber£10Amazon →