Part of Ward Property Services UK LtdA single hot shower can release well over a litre of water vapour into the air in a few minutes. If that vapour is not extracted, it migrates into landings, bedrooms and wardrobes and condenses on the first cold surface it meets. Bathrooms are therefore the biggest single moisture source in most homes, and bathroom ventilation is the highest-value improvement you can make.
The problem is rarely the absence of a fan — it is the performance of the fan that is there. Long or crushed ducting, missing backdraught shutters, a fan wired to run only with the light and an overrun of two minutes, or a unit rated for a cloakroom fitted in a family bathroom. We test actual airflow and specify accordingly.
Common signs
- ✓ The mirror staying misted for a long time after showering
- ✓ Black mould on ceiling, grout and silicone sealant
- ✓ Peeling paint on the bathroom ceiling and door
- ✓ Water droplets on walls and windowsills after a shower
- ✓ Damp landing carpet outside the bathroom door
Likely causes
- • Underpowered or failing extract fan
- • Flexible ducting that is kinked, sagging or uninsulated
- • No fan overrun, or the fan switched off at the isolator
- • Bathroom door sealed too tightly with no air replacement path
- • Cold external wall and single-glazed window creating dew points