Building Reg.s for ventilation
Ventilation is most effective when air is extracted close to the vapour source; bathroom, kitchen, drying clothes and occupied rooms.
Modern life and the drive to conserve energy means properties should comply with Building Regulation 2010 Part F requirements to stay dry and mould free. This is best achieved with mechanical extractor fans.
See surveyor.tips/vent_regs specifically P39 and P19:
- Bathroom 15 l/s with a 30-minute overrun.
- Kitchen 30 l/s adjacent to hob; or 60 l/s elsewhere in kitchen.
Building Reg.s part F failure
A majority of ventilation systems are not properly tested and fail to comply with Building Reg.s. Part FWhy????
Vent reg.s typically fail because;
- Flexible ducting is used too much, dramatically reducing flow rates over manufacturers published data, compared to rigid ducting.
- Most ventilation installers don’t change factory settings, such as for overruns (which should be set to 30 minutes in bathrooms).
- It is rare that the airflow exiting a property is tested, as should be the case, so leaks and other errors will go unnoticed.
- Always test ventilation outflow for all bathroom and kitchen extractors with an anemometer (Testo make the best known).
- If you can’t reach the outflow, then test at the extractor side, but look for reasons why there could a leak in the ducting.
- Check the overrun setting is 20 minutes or more (ideally 30 minutes), if not note the overrun setting and consider the effect.
- Consider if the occupants typically leave the bathroom door closed or open.
- Consider whether the kitchen extractor fan is used and is effective such kitchen’s open plan to another room.