Where the numbers come from
Two documents say the same thing from different directions. NCC 2022 Volume One Clause F6D12 requires a commercial kitchen to have an exhaust hood complying with AS 1668.1 and AS 1668.2 once the cooking equipment passes those inputs. AS 1668.2-2012 Clause 3.3.1(b) defines the same thresholds as Type B effluent, and adds the words that catch most fit-outs: or any deep fryer appliance.
| Trigger | Value |
|---|---|
| Single apparatus, electric | above 8 kW |
| Single apparatus, gas | above 29 MJ/h |
| Several apparatus, electric, per m² of room floor | above 0.5 kW/m² |
| Several apparatus, gas, per m² of room floor | above 1.8 MJ/h per m² |
| Deep fryer | any rating |
What is exempt
Clause 3.3.1(b) lists the exemptions: commercial coffee machines, microwaves and similar low-power equipment used infrequently or solely for reheating, space heating, plant enclosures, domestic apparatus, and equipment that does not cause objectionable conditions.
Two traps
- Electric does not exempt a fryer. Two electric fryers still need a canopy, a grease duct and a fan. What electric removes is the gas interlock and the flue, and it allows a 600 mm filter clearance instead of 1050 mm.
- Dishwashers. AS 4674-2004 Clause 2.5.2 requires extraction where a dishwasher or similar vents steam that collects, or is likely to collect, on walls and ceilings. Several WA councils name dishwashers directly.
If your permit is assessed under NCC 2025
NCC 2025 calls up AS 1668.2:2024. Government guides that reproduce that edition (ACT Health, August 2025, and Campbelltown City Council in NSW) list a hood over a single deep fryer above 3.6 kW, and over cooking process Types 3 to 6 above 3.6 kW combined where they sit within 2 m of each other. WA adopted NCC 2025 on 1 May 2026, with NCC 2022 still usable until 30 April 2027, so ask the building surveyor which edition applies before you design.
Designing or fitting out a commercial kitchen in WA? Send your equipment list and floor plan for a fixed-fee design your contractors can price.
Send your equipment listQuestions
When does a commercial kitchen need an exhaust hood in Australia?
Once any single cooking apparatus exceeds 8 kW electric or 29 MJ/h gas, or several appliances together exceed 0.5 kW per m2 electric or 1.8 MJ/h per m2 of floor area (NCC 2022 Clause F6D12). AS 1668.2-2012 Clause 3.3.1(b) adds any deep fryer, regardless of rating. Washing equipment that vents steam onto walls and ceilings also needs extraction under AS 4674-2004 Clause 2.5.2.
Do electric fryers need a canopy?
Yes. AS 1668.2-2012 Clause 3.3.1(b) treats any deep fryer as producing Type B effluent regardless of rating, so it needs a hood, a grease duct and an exhaust fan. Electric removes the gas interlock and flue, and allows a 600 mm filter clearance instead of 1050 mm.
More memos
General guidance, not a design. Clause references are to AS 1668.2-2012 with Amendments 1 and 2 (called up by NCC 2022) and AS/NZS 5601.1:2022; NCC 2025 calls up AS 1668.2:2024, where numbering and some values differ, so confirm the edition with your building surveyor. I do the design and calculations as a mechanical engineer (MIEAust); the mechanical contractor installs, commissions and certifies, and a licensed gasfitter certifies gas work. More: kitchen exhaust and ventilation design in Perth · all design memos