Is Approved Document F the law?

No. The legal requirement is Part F of the Building Regulations, which says buildings must have adequate ventilation. Approved Document F is the government guidance showing one accepted way to meet it. You can comply by other means if you can demonstrate the ventilation is adequate, but following the Approved Document is the usual route.

Which edition of Approved Document F applies?

For England, the 2021 edition applies to work from 15 June 2022. A 2026 edition has been published and applies from 24 March 2027 as part of the Future Homes Standard. Scotland, Wales and Northern Ireland have their own separate ventilation rules.

Does Part F require MVHR?

No. Part F sets the ventilation a home must have but does not mandate any particular system. MVHR is one compliant option, and it is often the most practical choice in very airtight homes, but continuous mechanical extract and other approaches can also comply.

Who checks Part F compliance?

Your building control body, either the local authority or an approved inspector, checks that the ventilation meets Part F. For mechanical systems they will expect to see commissioning records showing the measured air flow rates.

Overview

Approved Document F, in plain English

Approved Document F is the government guidance on how to meet Part F of the Building Regulations, which requires every home to have adequate ventilation. It sets minimum extract rates for kitchens, bathrooms and other wet rooms, a minimum whole-dwelling supply of fresh air, and rules for purge ventilation and commissioning. It is guidance on how to comply, not the law itself, and it applies to new homes and to many alterations.

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 is Approved Document F?

Approved Document F is the government guidance on how to meet Part F of the Building Regulations, which requires adequate ventilation in buildings. Volume 1 covers dwellings and Volume 2 covers other buildings. It is not the law itself; it is the practical guidance that shows one accepted way to comply. The current edition for England is the 2021 edition, in force since 15 June 2022.

Part F is the legal requirement. Approved Document F is the how-to. Following it is the normal route to compliance, but you can meet Part F by other means if you can show the ventilation is adequate. A separate 2026 edition has been published and takes effect on 24 March 2027 under the Future Homes Standard. Scotland, Wales and Northern Ireland set their own ventilation rules rather than using Approved Document F.

Sources: GOV.UK

What extract rates does Part F require?

For continuous mechanical extract systems, 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. These rooms are ventilated at source because they produce the most moisture and pollutants. Intermittent extractor fans have their own, higher minimum rates.

The intermittent rates, for a fan switched on as needed rather than running continuously, are higher: 30 l/s in a kitchen with a cooker hood extracting 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. A continuous system runs at a low background rate at all times and boosts to the high rate when needed, which is why its high-rate figures are lower than an intermittent fan that only runs occasionally.

Sources: GOV.UK

What is the whole-dwelling ventilation rate under Part F?

The whole-dwelling ventilation rate is the fresh air the whole home needs. Under Approved Document F it must meet the greater of two figures: 0.3 litres per second for every square metre of internal floor area, and a rate set by the number of bedrooms. The bedroom figures are 19 l/s for one bedroom, then 25, 31, 37 and 43 l/s for two, three, four and five bedrooms.

You add all the floor areas in the home, including each storey, for the floor-area method. For the bedroom method you read the figure straight from Table 1.3, adding 6 l/s for each bedroom beyond five. A home with only one habitable room uses 13 l/s. Whichever method gives the larger number is the rate the supply air must meet. Our Part F rates page works through an example.

Sources: GOV.UK

Does Part F apply to renovations and extensions?

Yes. Part F applies to new dwellings and to many alterations, not only new builds. Work that affects ventilation, such as an extension, a loft conversion, replacing windows, or making a home more airtight, can bring Part F into play, because cutting draughts without providing controlled ventilation can cause condensation and poor air quality. Your building control body confirms what applies to your project.

A common trap is a fabric upgrade, new windows or insulation, that makes a home much more airtight without any matching change to ventilation. The home ends up under-ventilated, and damp and mould follow. Approved Document F includes specific guidance for work in existing dwellings so that improving efficiency does not create an air quality problem.

How is Part F compliance proved?

Mechanical ventilation systems must be commissioned, which means setting and measuring the actual air flow rates and recording them. The measured results are given to the building control body on a commissioning sheet. Without commissioning there is no evidence that the system delivers the rates Part F requires, and the work may not pass building control.

Commissioning matters because a system can be installed perfectly and still under-perform if it was never balanced, or if ducting is crushed or too long. The commissioning record shows the real, measured flow at each terminal against the rates Approved Document F requires. For a homeowner it is the document that proves the ventilation actually works, not just that a unit was fitted.

Sources: GOV.UK

Questions

Is Approved Document F the law?: No. The legal requirement is Part F of the Building Regulations, which says buildings must have adequate ventilation. Approved Document F is the government guidance showing one accepted way to meet it. You can comply by other means if you can demonstrate the ventilation is adequate, but following the Approved Document is the usual route.
Which edition of Approved Document F applies?: For England, the 2021 edition applies to work from 15 June 2022. A 2026 edition has been published and applies from 24 March 2027 as part of the Future Homes Standard. Scotland, Wales and Northern Ireland have their own separate ventilation rules.
Does Part F require MVHR?: No. Part F sets the ventilation a home must have but does not mandate any particular system. MVHR is one compliant option, and it is often the most practical choice in very airtight homes, but continuous mechanical extract and other approaches can also comply.
Who checks Part F compliance?: Your building control body, either the local authority or an approved inspector, checks that the ventilation meets Part F. For mechanical systems they will expect to see commissioning records showing the measured air flow rates.