Bathroom Extractor Fan Costs UK — What to Charge to Fit One in 2026

Why Bathrooms Need Mechanical Extraction

A bathroom is the wettest room in the house, and a shower or bath dumps a large volume of warm, moist air into a small space. Without somewhere to go, that moisture condenses on the coldest surfaces — windows, tiles, ceilings and the wall behind the WC — and over time you get streaming condensation, black mould and damp. Mechanical extraction pulls that moist air out before it can settle.

It is also a legal requirement. Under Building Regulations Part F (ventilation), a bathroom or shower room with no openable window must have mechanical extract ventilation, and even rooms with a window are expected to have it in new builds and most refurbishments. A bathroom without working extraction is a recurring callback waiting to happen, so it pays to install one properly the first time.

Fan Types and What They Cost

The fan you specify makes a big difference to both the price and how well the job performs. There are three broad categories you'll quote, plus a set of control options that sit on top of any of them.

Axial Fans (Wall or Ceiling Mounted)

The standard, lowest-cost option. An axial fan sits in the wall or ceiling and pushes air a short distance straight out through the wall behind it or up into a short duct. They're cheap, quick to fit and ideal where the fan is on an external wall or directly below the loft with a short, straight duct run to the outside.

The catch is that axial fans lose performance rapidly over any length of ducting or around bends. If the air has to travel more than a metre or two, or turn several corners, an axial fan will struggle to shift its rated airflow. For a typical wall-mounted job on an external wall, supply and fit lands around £120–£250 depending on the fan and access.

Inline and Centrifugal Fans (Mounted in the Loft)

Where the bathroom is internal, or the duct run to the outside is long or has several bends, you need a fan that can develop more pressure. An inline fan sits in the loft along the duct run, with a grille in the bathroom ceiling connected by flexible or rigid ducting up to the unit and then out through a tile vent, soffit or gable wall. A centrifugal fan uses a different impeller design to push air against the resistance of a long duct.

The practical difference: axial fans are for short, direct runs; inline and centrifugal fans are for everything longer or more awkward. Mounting the fan in the loft also makes the bathroom quieter, since the motor noise is away from the room. Expect supply and fit for an inline or centrifugal install with ducting to be in the region of £200–£500, with the upper end reflecting longer runs, awkward loft access and higher-spec units.

Control Options: Timer, Humidistat and PIR

Any of the above can be specified with different control methods, and customers often don't know the difference — so it's a useful upsell to explain:

• Timer: the fan runs while the light is on and overruns for a set period (typically 5–20 minutes) after the light is switched off. The cheapest controlled option and the most common.
• Humidistat: the fan triggers automatically when humidity rises above a set threshold, so it runs after a shower even if nobody touched the light. Best for genuine condensation problems and around £15–£40 more on the unit.
• PIR (motion sensor): the fan starts when someone enters the room. Useful where the fan is wired independently of the lighting circuit.

A humidistat-and-timer fan is the sensible default recommendation for a customer fighting mould — it costs a little more but actually deals with the problem rather than just clearing the air while the light happens to be on.

Minimum Extract Rate — Part F

Specifying a fan that is too weak is the most common reason an extractor fails to cure condensation. Building Regulations Part F sets a minimum intermittent extract rate for a bathroom of around 15 litres per second (a utility room is 30 l/s and a kitchen 30–60 l/s). Most decent 100mm (4 inch) axial bathroom fans are rated to meet this in free air — but remember the rated figure is measured with no ducting attached.

Once you add a long or bendy duct run, the real-world airflow drops, sometimes well below 15 l/s. This is exactly why an internal bathroom with a long duct needs an inline or centrifugal fan rated comfortably above the minimum, not a budget axial unit that only just hits 15 l/s on paper. Quote the right fan for the duct run and you avoid the callback.

The Electrics — Zones, Isolation and Part P

A bathroom is a special location under BS 7671, divided into zones based on proximity to the bath or shower. The fan and its wiring must be suitable for the zone they sit in — IP-rated where required — and the installation must include a means of isolation so the fan can be safely worked on. A common arrangement is a fused spur or a triple-pole fan isolator switch outside the bathroom, with the fan supplied from the lighting circuit (and, for timer models, a permanent live plus a switched live).

Electrical work in a bathroom is notifiable under Building Regulations Part P in England and Wales. A registered electrician can self-certify the work through a competent person scheme; an installer who is not registered would need to notify building control. This is a key reason a fan fitted by a qualified electrician costs more than one a general builder bodges in — and why, on a new install or any job adding a new circuit or isolation, you should price an electrician's time properly rather than absorbing it.

Ducting — Vent to Outside, Not the Loft

The single most common defect in DIY and cheap fan installs is ducting that vents into the loft rather than to the outside. Dumping warm, moist bathroom air into a cold roof space causes condensation on the timbers and insulation, leading to damp, rot and mould in the loft — a problem worse than the one the fan was meant to solve. The duct must terminate outside, through a wall vent, soffit vent, tile vent or gable grille.

Use insulated ducting for any run through a cold loft. Uninsulated duct in a cold space lets the warm extract air condense inside the duct itself; that water runs back down and drips out of the bathroom grille, leaving the customer convinced the fan is leaking. Insulated duct, kept as short and straight as practical with gentle bends, also preserves airflow so the fan actually achieves its rated extract rate. Skimping on ducting is a false economy you'll pay for in callbacks.

Like-for-Like Swap vs New Install

The biggest swing in price is whether you're reusing existing infrastructure or building it from scratch.

• Like-for-like replacement: the cabling, isolation and ducting already exist and you're swapping a failed fan for a new one in the same position. This is largely labour — typically £80–£180 in labour, plus the fan — and can be done in well under an hour for an accessible unit.
• New install with new ducting and cabling: no existing provision, so you're running a new spur or lighting feed, fitting an isolator, cutting and fitting the fan position, running insulated duct through the loft and forming the external vent, then making good. This is most of a day's work, often a two-trade job (electrician plus making-good), and prices accordingly.

Be clear in your quote which of these you're pricing. A customer who's been quoted "£100 to fit a fan" by someone assuming a like-for-like swap will baulk at your new-install price unless you spell out the extra cabling, ducting and making good they're actually paying for.

What Affects the Quote

Beyond fan type and swap-versus-new, the main factors that move the price are:

• Access: a fan on an accessible external wall is quick; a ceiling fan needing loft work, or a flat with no loft and a long internal duct, takes far longer.
• Duct length and routing: long runs and multiple bends mean more material, more time, and a higher-spec fan to overcome the resistance.
• Whether an electrician is needed: a notifiable Part P job adds qualified labour and certification; a like-for-like swap on an existing circuit may not.
• Fan quality: a budget axial fan is a few pounds; a quiet, low-energy humidistat inline unit from a quality brand can be £80–£150+ on the supply alone.
• Making good: a new install through a tiled wall or a finished ceiling needs patching, filling and sometimes decorating — easy to forget when quoting, and easy to lose money on if you don't.

Quick Reference: Bathroom Extractor Fan Prices UK 2026