Part F ventilation rates explained

Approved Document F (2021 edition) sets minimum extract rates for homes in England: 15 litres a second for a bathroom, 30 for a kitchen with a cooker hood or 60 without, 30 for a utility room and 6 for a WC, with whole-home rates based on the number of bedrooms.

What are the intermittent extract rates?

Kitchen 30 l/s with a cooker hood or 60 l/s elsewhere; utility 30 l/s; bathroom 15 l/s; WC 6 l/s.

What are the whole-home rates?

For continuous systems the whole-dwelling rate rises with bedrooms: 19 l/s for one bedroom, 25 for two, 31 for three, 37 for four and 43 for five, and supply should be at least 0.3 l/s per square metre of floor where that is higher.

Does airflow need testing?

Yes. Mechanical ventilation in new dwellings must be tested with a calibrated flow device and the results recorded on a commissioning sheet for building control.

What about trickle vents?

Natural or extract-only ventilation relies on background ventilators in habitable rooms; whole-home MVHR should not have them.

Do these rates apply in Wales, Scotland and Northern Ireland?

No. Each nation has its own guidance, so rates and paperwork can differ. We design to the rules where the job is.

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Sources

• BEAMA guidance on Part F for dwellings in England
• Welsh Government: building regulations approved documents

Related services

Airflow testing and commissioning

Calibrated flow-hood testing and commissioning sheets for fans, MEV and MVHR.

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Ventilation for new builds, extensions and lofts

Part F designs, MVHR or extract installs and the commissioning paperwork building control needs.

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