Kitchen Extraction and Ventilation: Grease, Fire Risk and Staying Compliant

The extraction canopy over your cookline is easy to ignore — it's above eye level, it hums away, and when it works you never think about it. But kitchen extraction is doing three jobs at once: pulling heat and steam out of the kitchen, removing the grease-laden vapour that cooking produces, and (on gas equipment) clearing combustion gases. When it fails, the consequences are discomfort, a hygiene problem, and — worst case — a duct fire.

This guide covers why extraction matters beyond comfort, the grease and fire risk, make-up air, the cleaning schedule that keeps it safe, and the compliance points inspectors check.

Grease build-up is a fire risk, not just a hygiene one

Every time you fry, grill or griddle, the extraction pulls grease-laden vapour up through the canopy, the filters and into the ductwork. Grease coats the inside of that system over time — and grease is fuel. A fire that starts on the cookline can flash up into a greasy duct and spread through the building in minutes. This is the single most important reason extraction cleaning is not optional.

The canopy filters catch the worst of it, but they don't catch all of it — the ductwork and the fan accumulate grease too, and they're the parts nobody sees.

Make-up air: the half everyone forgets

Extraction removes air from the kitchen — that air has to be replaced. Without enough make-up air (fresh air coming in to replace what's extracted), the kitchen goes into negative pressure: doors are hard to open, flames on gas appliances burn poorly, and the extraction itself works badly because it's starved of air. Good extraction is a balanced system — air out, air in — not just a powerful fan.

This matters even more once you add gas appliances (see our gas guide): the extraction has to run whenever the gas is on, which means the fan and its power supply belong on your critical-loads list for load shedding.

The cleaning schedule that keeps it safe

Grease build-up is gradual, so the schedule is what catches it:

• Canopy filters — clean frequently (daily to weekly depending on volume). These are the first grease trap and the easiest to reach.
• Canopy interior and exterior — wipe down on the weekly clean.
• Ductwork and fan — professional deep clean on a periodic cycle. How often depends on how much frying and grilling you do: a high-volume fried-food operation needs it far more often than a light-prep café. Your extraction cleaning contractor can advise on the interval for your actual grease load.

A canopy that drips grease or a filter that's gone stiff with build-up is already overdue. If you can see grease, it's past time.

The compliance points inspectors check

Extraction sits at the intersection of food safety and fire safety:

• Grease and cleanliness of the canopy and filters are a food-premises hygiene point under Regulation R638.
• Duct cleaning records are your proof the fire risk is managed — insurers and fire officers ask for these, and after any fire the first question is "when was the duct last cleaned?"
• Adequate ventilation of the premises is itself a requirement — the kitchen has to be ventilated for the work being done in it.

Keep the duct-cleaning certificates with your food-safety records. They're the same kind of evidence as your temperature logs and cleaning schedule: proof the system is managed, not occasional.

Frequently asked questions

How often should extraction ductwork be professionally cleaned?

It depends on your grease load. A high-volume frying or grilling operation needs duct cleaning far more often than a light-prep kitchen. Your extraction cleaning contractor can assess the actual build-up and set the interval. The canopy filters, by contrast, are an in-house job on a daily-to-weekly cycle.

Is extraction really a fire risk?

Yes — grease coating the inside of the ductwork is fuel, and a cookline fire can flash up into a greasy duct and spread through the building. Regular duct cleaning is the control, and the cleaning records are your proof for insurers and inspectors.

What is make-up air and why does it matter?

Extraction removes air from the kitchen; make-up air is the fresh air that replaces it. Without enough, the kitchen goes into negative pressure — doors stick, gas flames burn poorly, and the extraction underperforms because it's starved of air. Ventilation is a balanced system, not just a fan.

Does extraction matter if I cook on electric, not gas?

Yes. Electric cooking still produces heat, steam and grease-laden vapour that must be extracted. Gas adds combustion gases on top, which makes extraction even more critical — but the grease and fire risk applies to any cookline.