What is the minimum extract rate for a bathroom under Part F?

For a continuous mechanical extract system the minimum high rate for a bathroom is 8 l/s. For an intermittent extractor fan the minimum is 15 l/s. Both figures come from Approved Document F Volume 1, the 2021 edition.

What is the kitchen extract rate under Part F?

A continuous extract system needs a minimum high rate of 13 l/s in a kitchen. An intermittent extractor fan needs 30 l/s if it is a cooker hood extracting outside, or 60 l/s otherwise.

Is the whole-dwelling rate based on people or bedrooms?

Approved Document F sets it by the number of bedrooms, using an assumed occupancy, and then takes the greater of that figure and 0.3 l/s per square metre of floor area. The bedroom method assumes two people in the main bedroom and one in each other bedroom.

What ventilation rate changes come in 2027?

From 24 March 2027 the Future Homes Standard sets the whole-dwelling supply rate at 6 l/s per bedroom, regardless of assumed occupancy, and requires background ventilators with a minimum equivalent area of 5,000 square millimetres in each habitable room.

Can I use a cooker hood with MVHR?

Yes, but a recirculating cooker hood is the better match. It filters grease and cooking smells through a charcoal filter and returns the air to the room, while the MVHR provides the kitchen extract Part F requires. Never duct a greasy cooker hood into the MVHR system, because grease fouls the ducts and heat exchanger. A separate externally ducted hood is possible but needs its own sealed vent so it does not disturb the MVHR.

Do I still need a kitchen extractor fan with MVHR?

No. The MVHR system provides the continuous kitchen extract that Approved Document F requires, so a separate wall or window extractor fan is not needed. Many people still fit a recirculating cooker hood over the hob to deal with grease and smells at source, but that is for comfort, not to meet the regulations.

Can I have a tumble dryer in a home with MVHR?

Yes, but use a condenser or heat pump tumble dryer, which is self contained and needs no vent to outside. Avoid a vented tumble dryer, because it punches a hole in the airtight envelope and dumps warm moist air that the MVHR then has to deal with. A heat pump dryer is the usual choice in an airtight home.

Approved Document F Explained: UK Home Ventilation Rules

Part F ventilation rates, in full

Approved Document F sets two kinds of minimum rate: extract rates that clear moisture from wet rooms, and a whole-dwelling rate for the fresh air supplied across the home. This page gives the exact figures from the 2021 edition for England, both the intermittent and continuous extract rates, and shows how to work out the whole-dwelling rate for any size of home.

By VentRight Editorial · Last updated 2026-07-08 · Impartial · Sourced

Part F continuous extract rates. Labelled: Kitchen, Utility room, Bathroom, WC. — Part F continuous extract rates — labels

kitchenKitchen — 13 litres per second minimum continuous extract high rate.

utilityUtility room — 8 litres per second.

bathroomBathroom — 8 litres per second.

wcWC — 6 litres per second.

What are the continuous extract rates under Part F?

For a continuous mechanical extract system, such as MEV or MVHR, Approved Document F sets minimum high extract rates of 13 l/s in a kitchen, 8 l/s in a utility room, 8 l/s in a bathroom, and 6 l/s in a WC. The system runs continuously at a low background rate and boosts to these high rates when a room needs more extraction.

On top of the high rates, the total continuous extract across the whole home at its background rate must be at least the whole-dwelling ventilation rate from Table 1.3. In other words, the wet-room extract and the whole-house supply are checked together, so a compliant system both clears moisture at source and moves enough total air through the home.

Sources: GOV.UK

What are the intermittent extract rates under Part F?

For intermittent extractor fans, the type switched on when a room is in use, the minimum rates are higher: 30 l/s in a kitchen with a cooker hood that extracts outside, 60 l/s in a kitchen without one, 30 l/s in a utility room, 15 l/s in a bathroom, and 6 l/s in a WC. The rates are higher because the fan only runs some of the time.

A recirculating cooker hood, one that filters and returns air to the room rather than ducting it outside, does not count as ventilation under Part F. If the kitchen extract does not vent outside, the 60 l/s figure applies. For a WC, purge ventilation such as an opening window can be used as an alternative to a fan.

Sources: GOV.UK

How do you calculate the whole-dwelling ventilation rate?

Work out both methods and take the greater. Method one is 0.3 litres per second for every square metre of internal floor area, adding all storeys together. Method two reads the rate from the bedroom table. For example, a four-bedroom home of 120 square metres gives 0.3 times 120, which is 36 l/s, by floor area, and 37 l/s by bedrooms. The whole-dwelling rate is the greater, so 37 l/s.

The floor-area method tends to govern in large open-plan homes, while the bedroom method tends to govern in compact homes with many bedrooms. Because Approved Document F requires the greater of the two, you cannot simply pick the smaller figure. Our ventilation rate calculator does this both ways for your home and shows which one applies.

Sources: GOV.UK

What is the whole-dwelling rate for each number of bedrooms?

From Table 1.3 of Approved Document F, the minimum whole-dwelling ventilation rate is 19 l/s for a one-bedroom home, 25 l/s for two bedrooms, 31 l/s for three, 37 l/s for four, and 43 l/s for five. Add 6 l/s for each bedroom beyond five. A home with only one habitable room uses 13 l/s. Remember this is compared against the floor-area figure, and the greater applies.

The bedroom method assumes an occupancy of two people in the main bedroom and one in each additional bedroom, which is why the rate steps up by 6 l/s per bedroom. It is a proxy for how many people the home is likely to hold, since more people means more moisture and carbon dioxide to remove.

Sources: GOV.UK

How do the ventilation rates change under the Future Homes Standard?

From 24 March 2027 the Future Homes Standard changes the whole-dwelling supply rate to a flat 6 litres per second per bedroom, regardless of assumed occupancy, which simplifies the calculation. It also requires background ventilators with a minimum equivalent area of 5,000 square millimetres in each habitable room. These figures come from the 2026 edition of Approved Document F.

The current 2021 rules stay in force for work until the changeover, with a transitional period for homes already under way. If you are designing now for completion close to the deadline, it is worth checking which edition your project will fall under. See our Future Homes Standard guide for the full picture.

Sources: GOV.UK

Questions

What is the minimum extract rate for a bathroom under Part F?: For a continuous mechanical extract system the minimum high rate for a bathroom is 8 l/s. For an intermittent extractor fan the minimum is 15 l/s. Both figures come from Approved Document F Volume 1, the 2021 edition.
What is the kitchen extract rate under Part F?: A continuous extract system needs a minimum high rate of 13 l/s in a kitchen. An intermittent extractor fan needs 30 l/s if it is a cooker hood extracting outside, or 60 l/s otherwise.
Is the whole-dwelling rate based on people or bedrooms?: Approved Document F sets it by the number of bedrooms, using an assumed occupancy, and then takes the greater of that figure and 0.3 l/s per square metre of floor area. The bedroom method assumes two people in the main bedroom and one in each other bedroom.
What ventilation rate changes come in 2027?: From 24 March 2027 the Future Homes Standard sets the whole-dwelling supply rate at 6 l/s per bedroom, regardless of assumed occupancy, and requires background ventilators with a minimum equivalent area of 5,000 square millimetres in each habitable room.
Can I use a cooker hood with MVHR?: Yes, but a recirculating cooker hood is the better match. It filters grease and cooking smells through a charcoal filter and returns the air to the room, while the MVHR provides the kitchen extract Part F requires. Never duct a greasy cooker hood into the MVHR system, because grease fouls the ducts and heat exchanger. A separate externally ducted hood is possible but needs its own sealed vent so it does not disturb the MVHR.
Do I still need a kitchen extractor fan with MVHR?: No. The MVHR system provides the continuous kitchen extract that Approved Document F requires, so a separate wall or window extractor fan is not needed. Many people still fit a recirculating cooker hood over the hob to deal with grease and smells at source, but that is for comfort, not to meet the regulations.; Source: GOV.UK
Can I have a tumble dryer in a home with MVHR?: Yes, but use a condenser or heat pump tumble dryer, which is self contained and needs no vent to outside. Avoid a vented tumble dryer, because it punches a hole in the airtight envelope and dumps warm moist air that the MVHR then has to deal with. A heat pump dryer is the usual choice in an airtight home.