Bathroom and Kitchen Extract Fan Rates (l/s) – Approved Document F
UK Building Regulations guidance (Approved Document F, Volume 1: Dwellings) says extract ventilation to the outside should be provided in kitchens, utility rooms, bathrooms and sanitary accommodation[1].
Intermittent extract (Table 1.1)
Room
l/s
m³/h
CFM
Kitchen, cooker hood extracting outside
30
108
64
Kitchen, no hood / hood not extracting outside
60
216
127
Utility room
30
108
64
Bathroom
15
54
32
Sanitary accommodation (WC)
6
22
13
Continuous extract — minimum high rate (Table 1.2)
Room
High rate l/s
Kitchen
13
Utility room
8
Bathroom
8
Sanitary accommodation
6
The sum of all continuous extract rates should be at least the whole-dwelling ventilation rate in the same document[1]. Conversions (m³/h, CFM) are our own arithmetic.
Installation points
Fans and terminals (not cooker hoods) as high as practicable and max 400 mm below the ceiling[1].
Cooker hood height per manufacturer, or 650–750 mm above the hob if unspecified[1].
Outside the UK, check your local code — but EPA's general advice is the same direction: run the bathroom fan or open a window when showering, and use exhaust fans when cooking[2].
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