UK cost guide
How much does it cost to replace a bathroom extractor in the UK?
Replacing a bathroom extractor fan is quoted per job by an electrician or ventilation installer. The price depends on the fan type, the duct route, whether an external grille is needed and whether the wiring is in place. Get a written quote that names the fan model and its extract rate.
Bathroom fans are the highest-value single fix in the damp-and-mould cluster. Getting one right often ends a ceiling-mould problem for far less than remedial works that would otherwise return every winter for years.
Last updated Reviewed by Vincent Pamenter
Cost breakdown — UK 2026
Ask for an itemised written quote for your property. Confirm VAT, access, structural repairs and hazardous-material handling before agreeing to work.
What sets the price
Like-for-like axial fan replacement
- Price basis (UK 2026)
- Written quote required
- What moves the price
- Same location, existing duct, existing wiring.
Humidistat / timer axial replacement
- Price basis (UK 2026)
- Written quote required
- What moves the price
- Fan model, humidistat vs basic timer, sealing.
Centrifugal fan (long duct runs)
- Price basis (UK 2026)
- Written quote required
- What moves the price
- Higher static pressure; better for 3m+ ducts.
New duct route + external grille
- Price basis (UK 2026)
- Written quote required
- What moves the price
- Length and route of duct, plastering, external drilling.
Inline / loft-mounted fan
- Price basis (UK 2026)
- Written quote required
- What moves the price
- Loft access, ducting, isolator switch.
Electrician-only labour (BYO fan)
- Price basis (UK 2026)
- Written quote required
- What moves the price
- Time on site, minimum call-out.
Continuous low-rate fan (dMEV)
- Price basis (UK 2026)
- Written quote required
- What moves the price
- Runs 24/7 at low rate with boost; excellent for chronic condensation.
Stop The Mould does not publish price ranges it has not verified. Every figure on this page is either free at the point of visit or our own published pricing; everything else needs a written, itemised quote for your property.
What drives the price up or down
The three cost levers are: fan spec, duct route, and whether the electrician is doing anything beyond the swap.
Pushes price up
Ceiling fan on an internal wall
The duct has to run several metres to an external wall or through the loft — labour goes up.
Pushes price up
Plastering after fitting
If the new fan doesn’t match the old cutout, the ceiling will need patching and painting.
Brings price down
External-wall bathroom
A short 100 mm duct straight through the wall to an external grille is the cheapest, best-performing setup.
Pushes price up
Continuous ventilation (dMEV) upgrade
Slightly higher spec fan and controls than a boost-only fan, but transformative in chronically damp bathrooms.
Pushes price up
Compliance/certification
A Part P notification for the electrical work adds a small admin cost via the electrician.
Brings price down
Existing isolator switch
If there’s already an isolator switch in ceiling void or airing cupboard, the electrician spends less time.
Brings price down
Bundle with lighting or shower work
Adding the fan to an existing electrician visit is usually cheaper than a standalone trip.
Cheaper-first alternatives
Before upgrading anything, check whether the old fan simply isn’t running. Blocked grilles, disconnected humidistats and burnt-out motors are ‘fixes’ that cost nothing.
Fan hums but doesn’t clear steam
Often a blocked external grille or a kinked flexible duct. A length of duct and a cleanup can fix it.
Fan never comes on
Check the isolator switch and the wiring to the light circuit — sometimes just a blown fuse.
Fan runs but bathroom stays humid
Longer run time or a cheap humidistat retrofit is often enough before a full replacement.
Regional variation, multiple quotes, and red flags
Prices vary by region, by trade and by how far a surveyor or contractor has to travel. Rather than relying on a national average, get two or three written quotes for your property and compare what each one actually includes.
A fair bathroom-fan quote should specify the make and model of the fan, the extract rate in l/s, whether the fan is humidistat-controlled, the duct diameter and length, and the electrical work involved.
Red flag
No extract rate (l/s) quoted
Building Regulations Part F specifies bathroom extract rates. A quote without them can’t demonstrate compliance.
Red flag
Recirculating (non-ducted) fan proposed
Recirculating fans do not remove moisture from the home. In a damp bathroom, they are close to useless.
Red flag
Flexible duct running uphill
Flexi ducts sag and trap condensate. Rigid or semi-rigid ductwork is standard for a durable install.
Red flag
No isolator switch mentioned
Legal fan installs typically include an accessible isolator. Its absence suggests a shortcut.
Red flag
‘Same-day install with quote by phone’
A proper quote requires seeing the ceiling void or wall route. Phone quotes are anchors, not commitments.
How to pick the right bathroom fan
For most UK bathrooms with an external wall, a 100 mm humidistat-controlled axial fan is the right tool at the right price. It responds to humidity, runs long enough after showers to clear the moisture, and doesn’t require behavioural change from occupants.
For internal bathrooms, long duct runs or apartments where the extract must reach a shared duct, a centrifugal or in-line fan handles the higher static pressure without stalling.
For homes with chronic condensation across multiple rooms, consider a dMEV (continuous low-rate) fan or a whole-house PIV unit — see our /cost/condensation-fix-cost guide for that decision tree.
Before you spend anything
If your ceiling mould is fresh and the fan is old, replacing the fan is almost always the right first spend. Send us a photo of the bathroom, the fan and the external grille and we’ll tell you what the fan is doing wrong before any electrician arrives.
This is general information, not medical advice. If you're worried about your health, contact your GP or NHS 111.
This is general information, not legal advice. For advice on your specific situation, contact Shelter, Citizens Advice, or a solicitor.
Cost FAQs
Can I fit a bathroom fan myself?
The fan swap itself can be a DIY job in some cases, but the electrical connection in a bathroom (Zones 1 and 2) is notifiable work. Most homeowners use a Part-P registered electrician.
How long should a bathroom fan run after a shower?
A humidistat fan should run until relative humidity drops below its threshold — typically 15–30 minutes after use. A timer fan should be set to 15–20 minutes overrun.
What size fan do I need?
Match or exceed that spec.
Do I really need a humidistat?
For rented properties and busy family homes, yes — the fan runs itself and doesn’t depend on tenants remembering. For a single occupant with a habit, a timer is enough.
Will a new fan alone fix ceiling mould?
In most condensation-pattern bathroom cases, yes. The mould itself still needs cleaning; the fan stops it returning.
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