About this calculator
Size an exhaust fan in L/s against the NCC condensation provisions for kitchens, bathrooms, toilets and laundries.
How it’s calculated
NCC 2022 Housing Provisions 10.8.2: at least 40 L/s from a kitchen and 25 L/s from a bathroom, toilet or laundry, discharged directly or through a duct to outdoor air.
Worked example
With these inputs:
- Room
- Bathroom
- Room length
- 3 m
- Room width
- 2.5 m
- Ceiling height
- 2.4 m
the result is:
- Extract rate
- 25 l/s
- NCC minimum (Housing Provisions 10.8.2)
- 25 l/s, discharged outdoors
- 8 air changes per hour
- 40 l/s
- Suggested duct
- 125 mm
Tips from the trade
- Rated airflow falls off with long or flexible ducts. Keep runs short and smooth.
- Duct to outside, never into the roof space.
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and the NCC and Australian Standards before ordering.