Ceiling Extractor Fans: Loft Ducting, Inline Fans, Rates and Zones

Updated October 2026 · Meteor Electrical guides · 9 min read

A ceiling extractor fan is often the most effective way to clear steam, because warm, moist air rises straight to the ceiling. The fan itself is the easy part; the ducting through the loft is what decides whether it works well and stays dry. This guide covers ceiling-mounted fans for bathrooms and kitchens, loft ducting, inline fans, extraction rates, zones and fire-rated ceilings.

For an overview of fan types and controls, see our guide to the types of bathroom extractor fan.

What is a ceiling extractor fan?

A ceiling extractor fan is mounted flush with the ceiling, with a duct running from the back of the fan through the loft or ceiling void to outside. There are three common set-ups:

• Ceiling-mounted fan: the motor sits in the ceiling behind the grille. Axial fans suit short ducts, while mixed-flow and centrifugal fans cope better with longer runs.
• Inline fan: the fan sits in the duct in the loft, with only a grille in the ceiling. It is quieter in the room and more powerful.
• Fan with light: a ceiling fan with a built-in light, and sometimes a heater, combining two or three jobs in one fitting.

Fans such as the Airflow iCON eco 15 100mm extractor fan can be fitted in a wall or ceiling. Check the maker’s instructions to confirm ceiling mounting before you buy.

How do you duct a ceiling extractor fan through the loft?

Loft ducting is where most ceiling fan problems start. A cold loft cools the warm, wet air in the duct, and the moisture condenses. Without the right duct and layout, that water runs back to the fan and drips from the grille.

1. Plan the shortest route. Pick the nearest suitable soffit, roof or gable position, and keep bends to a minimum. Every metre and bend reduces airflow.
2. Use insulated duct across the loft. Insulated duct keeps the air warmer, so much less condensation forms. Rigid duct has the least resistance; if you use flexible duct, pull it taut and avoid sags.
3. Fit a condensation trap. Fit it near the fan on any vertical section, so water that forms in the duct is caught before it can drain back into the fan.
4. Give the duct a fall to the outside. Lay the horizontal run with a slight fall away from the fan, so any condensate drains out of the vent rather than back into the room.
5. Terminate outside. Connect to a soffit vent, roof vent or wall grille. Never leave the duct discharging into the loft.
6. Seal and support every joint. Use clips and duct tape or connectors, and support the duct so it cannot sag between joists.

For the ducting itself, see our 100mm PVC ducting (6m), and for wall terminations a 100mm gravity shutter. Grilles, shutters and more are in our fan accessories range.

When should you fit an inline fan in the loft?

An inline fan sits in the duct in the loft, with a grille in the ceiling. Inline fans are usually mixed-flow or centrifugal inside, so they build enough pressure for longer runs, and because the motor is away from the room they are often the quietest option.

Choose an inline fan when:

• the duct run to outside is long or has several bends;
• the room is an en-suite next to a bedroom, where noise matters;
• the grille is directly above a shower or in a wet room;
• you want to extract from more than one grille, where the fan is designed for it.

Fit the fan where it can be reached for cleaning and replacement, and fit the isolator in an accessible position outside the bathroom zones. Options include the Airflow Aventa AV100T 100mm in-line fan with timer, the Airline 100 inline extract fan with timer and the XIMX 125mm inline mixed-flow fan. A timer fan normally needs 3 core and earth from the isolator; see our guide to 3 core and earth vs twin and earth.

What extraction rate does a ceiling fan need?

In England, Approved Document F sets minimum intermittent extraction rates for each room. The figures below are a guide only: Wales, Scotland, Northern Ireland and Ireland each have their own guidance, and the rules for new and existing homes can differ, so always check what applies to your job.

These rates apply to the fan as installed, not to the figure on the box. Long ducts, bends and grilles all reduce real airflow, which is why a fan that looks powerful on paper can underperform in a loft. See Approved Document F on gov.uk and our guide to choosing a powerful bathroom extractor fan for more detail.

Ceiling extractor fans for kitchens

A kitchen ceiling fan has to move more air than a bathroom fan, because cooking produces steam, heat, grease and smells. Without a cooker hood, Approved Document F asks for 60 l/s, so a larger fan and duct (often 125mm or 150mm) is common.

• Site the fan away from the hob’s direct heat, but close enough to capture steam.
• Choose a fan suitable for kitchen use, and clean or replace any grease filters regularly.
• Keep the duct as short as possible, with the same condensation precautions as a bathroom.

The Airflow iCON 30 extractor fan with auto-iris shutter is in our kitchen extractor fans range.

Bathroom zones and IP ratings for ceiling fans

BS 7671 Section 701, and I.S. 10101 in Ireland, divide a bathroom into zones based on how close they are to water. Zone 3 no longer exists; anywhere beyond zone 2 is simply outside the zones.

Many bathroom ceilings are about 2.4m high, which is above the 2.25m zone height, so a ceiling fan is often outside the zones unless the shower head is fixed higher. Measure before you choose. Where the fan is in zone 1, it must be IPX4 or better and rated for that position, and fans directly above the shower are often 12V SELV models, with the transformer fitted outside the zones. The Xpelair Simply Silent 100mm SELV bathroom fan with timer is one example.

For more on ratings, see our IP rating guide and our guide to the types of bathroom extractor fan, which explains SELV in more detail.

Fitting a fan in a fire-rated ceiling

Some ceilings are part of the building’s fire protection, for example in flats, loft conversions, and rooms above an integral garage. Cutting a hole for a fan and duct weakens that protection, so the opening must be restored to the same fire rating.

• Use a fan or ceiling kit tested for fire-rated ceilings, or an intumescent fire sleeve or damper as the fan maker or specifier recommends.
• Do not enlarge the hole beyond what the fan needs, and seal around it with suitable fire-rated sealant.
• If you are unsure whether a ceiling is fire-rated, check with building control or the building’s fire strategy.

The same principle applies to downlights in bathroom ceilings. See our guide to fire-rated vs standard bathroom downlights.

Which features are worth having?

Beyond the fan type, these features make the biggest difference day to day:

• Overrun timer: keeps the fan running for a set time after the light goes off. In a room with no openable window, Approved Document F asks for a 15 minute overrun.
• Humidistat: starts and stops the fan automatically as humidity changes. The Airflow iCON humidity and timer module adds this to compatible iCON fans.
• Quiet running: worth paying for in en-suites. Inline fans are often the quietest because the motor is out of the room.
• Trickle (continuous) running: a low background speed that boosts when needed, useful in airtight homes.
• Delayed start: waits a short time before starting, so quick visits at night do not set the fan going.
• Integrated light: a fan and light in one fitting, which can save a second hole in the ceiling.

Video: Simply Silent extractor fan step-by-step installation. Credit: XpelairUK on YouTube.

Ceiling extractor fan checklist

• Find the shortest, straightest duct route to a soffit, roof or wall termination.
• Use insulated duct across the loft, with a condensation trap and a fall to the outside.
• Check the extraction rate the room needs and allow for duct resistance.
• Measure the zone position and choose IPX4 or SELV where needed.
• Check whether the ceiling is fire-rated before cutting.

Getting a ceiling extractor fan right

A ceiling extractor fan works best when the duct is short, insulated and laid to fall to the outside. Choose an inline fan for long runs or quiet rooms, check the extraction rate for a bathroom or kitchen, and confirm the zone, IP rating and fire rating before you cut the ceiling. If in doubt, use a qualified electrician.

Need help choosing? Call our team on 028 8675 1515 (048 from ROI), Monday to Friday, 8am–5pm.

FAQs

Where should the duct from a ceiling extractor fan go?

It must go to outside, through a roof vent, a soffit vent or a grille in a gable wall. Never leave it discharging into the loft, because the warm, wet air will condense on the timbers and insulation. Keep the run as short and straight as possible.

Do I need insulated ducting for a ceiling extractor fan?

Yes, where the duct crosses a cold loft. Insulated duct keeps the air warmer, so far less condensation forms inside it. Add a condensation trap near the fan and lay the duct with a slight fall towards the outside so any water that does form drains away.

Can you put an extractor fan in the ceiling above a shower?

Yes. If the fan is within zone 1, directly above the shower and below 2.25m or the highest fixed shower head, it must be at least IPX4 and rated for zone 1, which often means a 12V SELV fan. Above that height it is outside the zones, but a bathroom-rated fan is still best.

What extraction rate does a kitchen ceiling fan need?

Approved Document F in England asks for 30 l/s from a kitchen where the extract is a cooker hood, or 60 l/s where the fan is somewhere else in the room. A bathroom needs 15 l/s. Rules in Wales, Scotland, Northern Ireland and Ireland differ in places, so check the guidance that applies.

Is an inline fan better than a ceiling extractor fan?

An inline fan is often better for long duct runs, wet rooms and en-suites, because it is more powerful and quieter in the room. A standard ceiling fan is cheaper and easier to reach for maintenance. For short runs with a nearby roof or soffit vent, a standard ceiling fan is usually enough.

Why is water dripping from my ceiling extractor fan?

Dripping usually means warm, moist air is condensing in cold ducting in the loft and running back to the fan. Insulate the duct, fit a condensation trap, remove any dips and give the duct a fall to the outside. Also check that the outside vent has not blown loose or become blocked.

Related guides

• Types of bathroom extractor fan explained
• How to choose a powerful bathroom extractor fan
• Bathroom electrics safety guide
• Fire-rated vs standard bathroom downlights