Why do homes get damp and mould?
Every home makes moisture. For example, showers, cooking, boiling the kettle, drying clothes and even breathing all put water into the air. When that moist air has nowhere to go, it settles on the coldest surfaces, such as windows, outside walls and bathroom ceilings.
Over time, that condensation turns into damp and mould. However, the fix is often simple: get the moist air out of the house before it settles, and that is exactly what an extractor fan does.
How extractor fans improve the air in your home
An extractor fan pulls steam, cooking smells and stale air out of the room and sends it outside. As a result, fresh air is drawn in to replace it, so the whole house feels fresher and less stuffy.
In addition, less moisture means less condensation on windows, less peeling paint and far fewer places for mould to grow.
Signs your home needs better ventilation
If you notice any of these, damp and mould are probably not far behind.
Wet windows in the morning
Condensation running down the glass every morning is the first sign that moist air is trapped inside.
Black spots on sealant
Black mould around the bath, shower or window frames usually means the room is not drying out properly.
A musty smell
For example, a damp, musty smell in a bedroom or cupboard often comes before mould you can see.
Peeling paint or wallpaper
Moisture behind paint and wallpaper also makes it bubble, flake and peel, especially on ceilings.
Mirrors that stay steamed up
If the bathroom mirror is still misty long after a shower, then the room has no real way to clear the steam.
Clothes drying indoors
In addition, drying washing indoors adds a lot of moisture, so the rooms around it need good ventilation.
Protect your home and your family
Damp and mould damage paint, plaster, sealant and furniture, and they make a home feel cold and stuffy. Therefore, a quiet, well-placed fan is one of the cheapest ways to protect your home.
A kitchen or bathroom refit is also the ideal time to add one, because the walls and ceilings are already open.
Keep tenants happy and stay compliant
Damp and mould are among the most common tenant complaints. In addition, rented homes must already be fit to live in under the Homes (Fitness for Human Habitation) Act 2018, and serious damp and mould can fail that test.
Awaab's Law is also set to extend to private rentals under the Renters' Rights Act 2025, although no start date has been confirmed yet. So fixing ventilation now puts you ahead. While you are at it, our guide on how often landlords need an EICR covers your electrical safety duties too.
How powerful should an extractor fan be?
Approved Document F, Volume 1: Dwellings sets the minimum extract rate for each wet room in a home. For example, a bathroom fan must be able to move at least 15 litres of air every second.
Bigger rooms with more steam need more airflow; therefore, we drill 100mm holes for bathrooms and toilets and 150mm holes for kitchens and utility rooms.
Extract rates: Approved Document F, Volume 1. Hole sizes: Find Electrician.
Which extractor fan is right for you?
There are three main types, and each one suits a different room.
Intermittent fans
These run when you switch the light on, and then keep going on a timed overrun. As a result, they suit most bathrooms and toilets.
Continuous fans (dMEV)
These run quietly all the time and boost when humidity rises. Therefore, they suit damp-prone flats and rooms without windows.
Inline fans
These sit in the loft or ceiling void, so you only see a small grille. They are also very quiet and powerful.
Quick damp and mould checklist
Before you call anyone, walk round the house and ask yourself these questions:
- First, does every bathroom, shower room and toilet have a working fan or an opening window?
- Does the fan keep running after the light goes off, for example on a timer or humidistat?
- Also, is it ducted to outside, rather than into the loft?
- Is the duct the right size, for example 100mm for bathrooms and 150mm for kitchens?
- In addition, is it quiet enough that nobody switches it off?
- Finally, has the fan been cleaned recently, because dust slows it down?
Damp and mould FAQs
Does an extractor fan improve air quality?
Yes, because it removes steam, cooking smells and stale air at the source. As a result, fresh air is drawn in to replace it.
Will an extractor fan stop damp and mould?
In most kitchens and bathrooms, it makes a big difference, because it removes moisture before it settles. However, damp from leaks or rising damp needs a different fix.
Do I need a fan if I have a window?
A window helps, but few people open one in winter. Therefore, a fan with a timer or humidistat clears the steam every time, whatever the weather.
Does Awaab's Law apply to private landlords?
Not yet. The Renters' Rights Act 2025 allows it to extend to private rentals; however, no start date has been confirmed.
What size hole do you drill for an extractor fan?
For bathrooms, en-suites and toilets we drill 100mm. For kitchens and utility rooms, however, we drill 150mm, since a bigger duct helps reach the higher extract rates.
How long does it take to fit an extractor fan?
It depends on the wall, the duct route and whether a new supply is needed. As a result, we confirm timings on your free quote.
Want fresher air and no more mould?
We fit extractor fans for homeowners and private landlords across London. See our extractor fan installation service, or message us for a free quote.
