Part F Ventilation Rates Reference
Ventilation system strategies and extract rates for dwellings, referencing Approved Document F: Ventilation, Volume 1 - Dwellings (2021 edition, effective 15 June 2022).
Extract Rates — System 1: Intermittent Extract Fans (AD-F 2021, Table 1.1)
| Room | Minimum Extract Rate | Notes |
|---|---|---|
| Kitchen (adjacent to hob) | 30 l/s | Cooker hood or extract fan above hob |
| Kitchen (elsewhere) | 60 l/s | Extract fan remote from hob |
| Utility room | 30 l/s | Intermittent extract |
| Bathroom | 15 l/s | With overrun timer (15 mins min) |
| Sanitary accommodation (WC only) | 6 l/s | Intermittent or continuous |
Extract Rates — Systems 3 & 4: Continuous Extract (AD-F 2021, Table 1.3/1.4)
| Room | Continuous (Low) Rate | Boost Rate |
|---|---|---|
| Kitchen | 13 l/s | 30 l/s (adjacent to hob) |
| Utility room | 8 l/s | 30 l/s |
| Bathroom | 8 l/s | 15 l/s |
| WC (no bath/shower) | 6 l/s | 6 l/s |
Whole Dwelling Ventilation Rate — Systems 3 & 4
The total continuous extract rate for the whole dwelling must be at least the greater of: (a) the sum of individual room rates, or (b) the whole-dwelling minimum based on number of bedrooms.
| Number of Bedrooms | Whole Dwelling Min. Rate (l/s) |
|---|---|
| 1 bedroom | 13 l/s |
| 2 bedrooms | 17 l/s |
| 3 bedrooms | 21 l/s |
| 4 bedrooms | 25 l/s |
| 5+ bedrooms | 29 l/s |
Background Ventilator Sizes — System 1 (AD-F 2021, Table 1.1)
| Bedrooms | Total Equivalent Area (mm²) |
|---|---|
| 1 | 25,000 |
| 2 | 35,000 |
| 3 | 45,000 |
| 4 | 55,000 |
| 5+ | 65,000 |
Purge Ventilation
Every habitable room requires purge ventilation. This is typically achieved by an openable window with a free area of at least 1/20th of the room floor area. Alternatively, a mechanical system capable of achieving 4 air changes per hour (ACH) is acceptable.
Related Calculators
Use the Ventilation Calculator for sizing, or the Part F Extract Fan Requirements page for fan sizing and noise limits.
Always check the latest edition of Approved Documents on the Planning Portal (planningportal.co.uk) as regulations are updated periodically.
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Last updated: April 2026
All calculations are estimates. Verify with your supplier.