Extractor fans & Ventilation Building Regs part F
The most common method of ventilation in domestic dwellings uses ‘Background Ventilation’ (Trickle vents to windows) and ‘Intermittent Extract Fans’.
Extractor fans are required in rooms where water vapour and pollutants are present to prevent them spreading to other parts of a building.
The Building Regulations relate to ventilation requirements in the following:
Kitchen
Cooker Hood Fan- 30 litres per second
Usually 650-750mm above hob.
Wall/Ceiling Fan 60 litres per second
Utility Room
Wall/ Ceiling Fan 30 litres per second
Bathroom
Wall/ Ceiling fan 15 litres per second
If located in Zones 1 or 2 must be IPX4
Fans with over-run facility must have TP isolation (switch outside Zones 0,1 & 2).
Separate WC
Wall/ Ceiling Fan 6 litres per second
Extract Fans General
Building Regulations state that extract fans may be manually or automatically controlled. Humidity control can reduce the risk of condensation and mould growth but is not suitable for sanitary accommodation.
Any automatic control must also provide manual over-ride to turn on if required.
For rooms with no natural light the fan must operate with the main light and have a 15 minute over-run.
It is recommend all fans have independent isolation for safety & ease of maintenance.
The installation of extract fans and ducting can compromise the integrity of fire barriers.
Source information:
As detailed in Electrician’s Guide to the Building Regulations
A full version of the Building Regulations can be downloaded from from
ElectriciansBlog.co.uk
