Keep your bathroom free of condensation and damp with the right choice of extractor fan. Learn about types, features to look for, and costs in our complete bathroom extractor fan buying guide.

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A bathroom extractor fan is one of the least glamorous purchases you'll make for your home, and one of the most important.

Without one, steam and moisture have nowhere to go except into your walls, ceilings, and grout, where they turn into condensation, mould, and expensive repair bills.

This guide covers everything you need to choose the right fan: the different types available, how to size one correctly, what UK building regulations require, and what installation costs to expect.

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Why bathrooms need extractor fans

Every time someone showers or runs a hot bath, the room fills with warm, moisture-laden air.

Left unchecked, that moisture settles on cold surfaces (tiles, ceilings, window frames) as condensation, which is the single biggest cause of bathroom mould.

A properly sized extractor fan pulls that moist air out before it has the chance to condense, which:

• Reduces odours and improves overall air quality

• Prevents condensation building up on walls and ceilings

• Protects paintwork, plaster, and grout from long-term damp damage

• Helps meet UK ventilation regulations for bathrooms without a window

Types of bathroom extractor fan

There are three main types of extractor fan used in UK bathrooms. Which one you need mostly comes down to how far the fan needs to push air before it reaches the outside.

Axial fans

Axial fans are the most common choice for UK bathrooms. They're compact, straightforward to install, and budget-friendly, making them well suited to smaller bathrooms with a short duct run of up to around 2-3m that vents directly through a wall or window.

Centrifugal fans

Centrifugal fans are more powerful and better suited to larger or poorly ventilated spaces. They're the better choice if your bathroom has a longer duct run (more than around 1.5m from an external wall) or needs to vent through the ceiling rather than a wall.

That extra power does mean centrifugal fans tend to run a little noisier than axial models.

Inline fans

Inline fans are less common and are typically installed out of sight in the loft space, connected to the bathroom via ducting.

They're the preferred option for long duct runs where the bathroom is a considerable distance from an external wall.

Their higher extraction rate and more involved installation make them the more expensive option of the three, but positioning the motor away from the room itself also makes them noticeably quieter in use.

Not sure which type suits your setup, or want help with installation costs? A qualified electrician can assess your bathroom and duct run properly, and any new wiring will need to meet Part P requirements regardless of which fan you choose.

How to size an extractor fan for your bathroom

Getting the extraction rate right matters more than most people expect. A fan that's too weak simply won't shift the moisture; running an oversized fan longer than necessary just wastes electricity.

To work out roughly what you need:

1. Calculate your bathroom's volume in cubic metres: length x width x height

2. As a rough guide, aim for an extraction rate of around 85m³/h for a small space such as an ensuite or shower room, rising to around 230m³/h for a larger family bathroom

UK Building Regulations Approved Document F set the legal minimum extraction rates, and these are worth knowing even as a homeowner, since any installer you hire will need to meet them:

• Intermittent fans (the most common type, switched on with the light or a humidity sensor): minimum 15 litres per second

• Continuous fans (running constantly at low speed, boosting when needed): minimum 8 litres per second

A fan that only just meets the legal minimum will pass an inspection, but many homeowners find a slightly higher-rated fan clears steam faster and copes better in bathrooms with a bath, shower, and no window.

What else to look for when choosing a fan

Beyond extraction rate, a handful of other features make a real difference to how much you'll actually enjoy (or forget about) your extractor fan.

Noise levels

As a general rule, axial fans run quieter than centrifugal fans.

It's possible to find super-quiet models rated as low as 16 dB, which is worth considering for an ensuite next to a bedroom, though anything under 30 dB is generally considered quiet enough for most households.

Energy efficiency

Modern, eco-friendly fans are usually labelled as such and are easy to spot. Otherwise, look for:

• Lower power consumption: most fans range from around 5W to 35W

• Timer controls: to limit how long the fan runs after use

• Humidity sensors: a humidistat measures air moisture and switches the fan on automatically when it's needed

Size and style

A 4-inch (100mm) extractor fan is normally enough for a standard-sized bathroom up to around 9m², while a 6-inch (150mm) fan suits larger or more frequently used bathrooms.

Style-wise, fans have moved well beyond plain white: chrome, matte black, and even gold finishes are now widely available if you want the fan to blend into your bathroom design rather than stand out.

Controls: manual, sensor, or timer

Fans can be switched manually via a pull cord, wired to come on with the light switch, triggered automatically by a humidity sensor, or set to run on a timer after use.

Many modern fans combine two or more of these, for example a light-switch trigger plus a run-on timer, which suits most households without any extra thought needed day to day.

Safety and IP rating

The IPX rating measures how resistant a fan is to water and moisture ingress, which matters more in a bathroom than almost anywhere else in the house.

• Extractor fans for bathrooms must have a minimum rating of IPX4 (splashproof), suitable for general bathroom use around showers and baths

• Fans installed inside or directly above a shower or bath (Zone 0) need a higher rating of IP67

• Fans in Zones 1 and 2 (the wider splash zone around the bath or shower) need at least IPX4

Bathroom circuits also require RCD protection, and any new wiring counts as notifiable electrical work under Part P, so it needs to be carried out or certified by a registered electrician.

On Checkatrade, you'll only find trades who meet our high standards and pass up to 12 checks.

Where to position your extractor fan

Positioning has a bigger impact on performance than most people realise.

Get it right and the fan does its job quietly in the background; get it wrong and you'll still find condensation on the mirror no matter how powerful the fan is.

• Fit the fan as close as possible to the source of steam, ideally in the space between the shower or bath and the door

• Mount it as high as practical, no more than 400mm below the ceiling, since warm, moist air rises

• Avoid unnecessary bends in the ducting: each 90-degree bend increases the risk of condensation building up inside the duct and dripping back into the fan

• Use insulated ducting for any run through a cold loft space, and make sure the duct slopes slightly downward towards the outside to help any condensation drain away rather than pooling

How to install an extractor fan through a wall

Looking to install an extractor fan through a wall? Follow this expert guide to learn how to complete this job to a professional standard.

Learn more

How much does a bathroom extractor fan cost?

Costs vary depending on the fan itself, whether you're replacing an existing unit or installing one from scratch, and how much rewiring or new ducting is involved.

As a general guide, replacing an existing fan is a simpler job than a brand-new installation, since the wiring, ducting, and external vent are usually already in place. Installing a fan where there wasn't one before costs more, largely because of the new ductwork and external grille required.

For a full breakdown of unit prices, installation labour, and what affects the total cost, see our dedicated cost guide.

Running costs are generally low. Modern, energy-efficient fans are inexpensive to operate, and leaving a fan on longer than necessary doesn't improve ventilation. A model with a humidity sensor or run-on timer is the more efficient choice long-term.

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Finding a tradesperson to install your extractor fan

Hiring a qualified electrician is strongly recommended for bathroom extractor fan installation, and for anything beyond a straightforward like-for-like swap, it's effectively essential.

Bathrooms are classed as "special locations" under UK electrical safety rules because of the proximity of water and electrics, so a registered electrician will:

• Ensure the installation is wired safely and correctly, including RCD protection

• Know the current building regulations for bathroom ventilation and IP ratings

• Certify the work where required under Part P, which matters if you come to sell the property

• Confirm ducting and positioning will actually achieve the extraction rate you're paying for

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Keeping your extractor fan running well

A fan that's never cleaned gradually loses performance, even if it seems to be running fine. Dust and grime build up on the blades and housing, which can make the fan louder, less effective, and shorten its working life.

• Wipe down the visible cover and grille every month or so to stop dust building up

• Give the blades, housing, and ducting a deeper clean every 3-6 months

• Watch for signs it needs attention: increased noise, lingering dampness after use, or visible dirt on the blades

If cleaning doesn't solve a noisy or underperforming fan, the issue is more likely to be a blocked duct, a fault with the wiring, or a unit that was undersized for the room in the first place.

Any of these are worth getting checked by an electrician rather than living with.

Checklist before you get an extractor fan installed

Extractor fan checklist

• Measure your bathroom to calculate the right extraction rate

• Check your duct run length and route

• Choose axial, centrifugal, or inline based on that run

• Confirm the correct IP rating for your bathroom zone

• Decide on manual, sensor, or timer controls

• Book a registered electrician for installation

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