Commercial Range Hood and Exhaust Canopy: How to Size, Specify, and Pass Your Council Inspection

What the Standard Actually Requires — in Plain Language

Most commercial kitchen operators know they need an exhaust canopy. Very few know what AS 1668.2-2012 specifies in practice. This gap is why non-compliant canopies are installed regularly, and why they fail inspection after the fit-out is otherwise complete.

1. 1

   Canopy dimensions and overhang

   The canopy must extend beyond the cooking equipment it covers on all open sides. The required overhang is not a flat number — it is calculated from the type of cooking equipment, its heat and pollution output category, and the mounting height of the canopy above the cooking surface. Higher-pollution equipment such as char grills and solid fuel cooking generates a wider and faster-rising thermal plume than lower-pollution equipment such as steamers or bain-maries, and the required overhang reflects this. A canopy sized to the exact footprint of the cooking equipment without the correct calculated overhang will fail inspection because the thermal plume escapes around the canopy edges.

2. 2

   Extraction rate

   The volume of air the canopy system must extract is calculated from the canopy face area, the cooking equipment’s pollution load category — AS 1668.2-2012 defines three categories: low, medium, and high — and the canopy mounting height above the cooking surface. A canopy designed for a low-pollution cooking line that is then positioned above a char grill or solid fuel installation will be under-extracted. The kitchen becomes hot, smoky, and non-compliant regardless of how the canopy looks from the outside.

3. 3

   Make-up air

   For every volume of air the exhaust system removes from the kitchen, an equivalent volume of replacement air must be supplied. This is make-up air. A kitchen without adequate make-up air operates under negative pressure: exhaust system performance drops, doors drag against the pressure differential, and combustion appliances risk backdrafting. Make-up air supply must be designed and installed as part of the ventilation scope — it is not an afterthought once the canopy is in.

4. 4

   Ductwork

   The duct connecting the canopy to the external discharge point must be sized to carry the required air volume at the correct velocity. Undersized ductwork creates back-pressure that reduces extraction effectiveness even when the fan unit is correctly rated. AS 1668.2-2012 also requires horizontal duct runs to be installed with a minimum slope — typically 1:50 toward a grease collection point — to prevent grease accumulation in the duct. Accumulated grease is a documented fire risk and an inspection failure. For more on grease fire risk in commercial kitchens and how ventilation contributes to prevention, see our grease fire risk guide.

Type I vs Type II canopies. A Type I canopy is required above any cooking equipment that produces grease-laden air — grills, fryers, woks, solid fuel equipment, and most commercial ovens. Type I canopies are fabricated with grease filters and constructed to contain and direct grease-laden airflow without leakage. A Type II canopy captures heat, steam, and odour from equipment that does not produce grease — dishwashers, steamers, and bain-maries. Installing a Type II canopy above grease-producing equipment is a specification error that will fail inspection.

The Four Most Common Inspection Failures

The canopy-related inspection failures we see in Queensland food premises are specification oversights made before installation, not equipment failures after it.

1. 1

   Canopy too small for the equipment footprint

   The canopy was sized to the cooking equipment dimensions without calculating the required overhang for the pollution category and mounting height. The inspector observes the thermal plume escaping around the canopy edges and documents the deficiency.

2. 2

   Extraction rate insufficient for the pollution load

   A canopy correctly sized for low-pollution equipment is placed above a char grill or solid fuel installation. The extraction system cannot keep up. Grease deposits accumulate on kitchen surfaces and the inspection documents the deficiency against the required extraction rate for the equipment in use.

3. 3

   No make-up air provision

   The canopy extracts correctly but no make-up air supply was installed. The kitchen runs under negative pressure, exhaust performance drops below the required rate, and the inspection documents the absence of make-up air as a deficiency.

4. 4

   Grease accumulation in ductwork

   Horizontal duct runs installed without the required slope toward a grease collection point accumulate grease over time. This is a documented fire risk and an inspection failure under both AS 1668.2-2012 and the Queensland Development Code.

What We Build and How We Quote

Commercial exhaust canopies fabricated in 304 grade stainless steel to AS 1668.2-2012. Wall-mounted and island Type I and Type II configurations. Canopies sized from the confirmed cooking equipment schedule — not from a plan drawing and not from a general estimate.

We visit the site before quoting. We take the confirmed equipment schedule, confirm cooking equipment positions and flue requirements, measure ceiling height and available duct path, and calculate the required canopy dimensions, extraction rate, and make-up air supply from AS 1668.2-2012 tables. Nothing is quoted from a plan without a site visit.

For full commercial kitchen fitout projects, the canopy is dimensioned alongside the stainless steel kitchen benching and sink benches from the same site measure so every element is coordinated before fabrication begins. See our commercial range hoods Brisbane page and exhaust canopy Brisbane page for further detail. For the full fitout scope including benching, sink benches, shelving, and canopy as a single commission, see our custom stainless steel kitchens Brisbane page.

Fabrication is carried out in our Burpengary East workshop. Installation is carried out by our own team — we do not subcontract. 12-month workmanship warranty on all installations.