Question 1

What is the minimum whole-dwelling ventilation rate?

Accepted Answer

Under Approved Document F (2021, Volume 1, Table 1.3) the minimum whole-dwelling ventilation high rate is 19 l/s for a 1-bed home, 25 l/s for 2 beds, 31 l/s for 3, 38 l/s for 4 and 44 l/s for 5 bedrooms. It must also be at least 0.3 l/s for every square metre of internal floor area, and the greater of the two figures applies.

Question 2

What are the intermittent extract rates for kitchens and bathrooms?

Accepted Answer

Approved Document F gives intermittent extract minimums of 30 l/s for a kitchen with the extract adjacent to the hob (60 l/s elsewhere), 30 l/s for a utility room, 15 l/s for a bathroom and 6 l/s for a WC. Continuous mechanical extract (MEV/MVHR) systems use a separate, lower set of continuous rates.

Question 3

How do I convert l/s to m3/h and air changes per hour?

Accepted Answer

Multiply litres per second by 3.6 to get cubic metres per hour. To get air changes per hour (ACH), divide the flow in m3/h by the room volume in m3 — that is (l/s x 3.6) / (floor area x ceiling height).

Question 4

Does this apply outside England?

Accepted Answer

The figures here are from Approved Document F for England. Wales, Scotland and Northern Ireland have their own technical guidance, and other countries use standards such as ASHRAE 62.2 in the US. Switch the flow units to m3/h for international comparison and always check the standard that applies in your jurisdiction.

Question 5

Why does ventilation matter for damp, mould and health?

Accepted Answer

Inadequate ventilation lets moisture and pollutants accumulate, raising surface humidity and condensation/mould risk and reducing indoor air quality. Meeting the extract and whole-dwelling rates removes moisture at source and supports duties such as the Decent Homes Standard and, for damp and mould, Awaab's Law.

Whole-dwelling (greater of the two)
1 / 2 / 3 / 4 / 5 bed	19 / 25 / 31 / 38 / 44 l/s
Floor-area floor	0.3 l/s per m²
Intermittent extract (minimum)
Kitchen (hob / elsewhere)	30 / 60 l/s
Utility	30 l/s
Bathroom	15 l/s
WC / cloakroom	6 l/s

Ventilation Rate Calculator

Whole-dwelling rate

Room extract check

Approved Document F — key rates

Using this correctly

Frequently Asked Questions

Log ventilation readings on-site.