How Often Should a Professional Contractor Clean a Hood Ventilation System?
Hood cleaning frequency is the interval at which the full exhaust system has to be cleaned back to bare metal by a contractor, and it is set by how much grease the cook line produces, not by how the kitchen looks. NFPA 96 puts solid fuel on a monthly interval, high-volume cooking on quarterly, moderate volume on semi-annual and low volume on annual. Most Hamilton restaurants running a fryer and a grill six or seven days a week land on quarterly or semi-annual. The practical question is not what the four categories say, it is which one your actual kitchen belongs to, and this page is about answering that.
How to place a real cook line in the right interval
Start with the equipment, not the seat count. What sits under the canopy decides the grease load, and the grease load decides the interval.
Work down the line and ask what each appliance puts into the air. A charbroiler, a wok range, a deep fryer bank and a solid-fuel grill are heavy contributors. A flat top, a salamander and a combi oven are moderate. A steam line and a bakery deck oven contribute very little. One heavy appliance on a full service day pulls the whole system toward a shorter interval even when the rest of the line is light.
Then look at hours. A cook line running sixteen hours across breakfast, lunch and a late close loads the system roughly twice as fast as the same equipment running one dinner service. Seasonality works the same way, so a patio kitchen that fires for five months is not on the same clock as a year-round dining room.
The published categories and the grease deposit limit behind them are on the NFPA 96 page. That page is the reference. This one is what to do when the kitchen refuses to fit neatly.
Hamilton kitchens that do not fit an interval neatly
Five situations come up constantly across the city. Each one has a defensible answer, and none of them is guesswork.
| The kitchen | Why the category is unclear | How to settle it |
|---|---|---|
| One charbroiler on an otherwise light line | The room reads as a cafe, but one appliance is doing all the grease production. | Categorise by the heaviest appliance at normal service hours, then let the first plenum inspection confirm or relax it. |
| A wok range or a tandoor | Output is heavy and constant, and deposits often carry further up the duct than a fryer does. | Treat as high volume from the start and check the duct interior at the first visit rather than waiting for a problem. |
| A seasonal patio or event kitchen | Heavy use for part of the year, closed the rest, so a calendar interval falls in the wrong place. | Book to the season: clean at the close, and mid-season if the line runs daily. Grease in an idle duct is still fuel. |
| A banquet hall or legion hall | Dark for weeks, then four heavy services in a weekend. Annual looks defensible on paper and is not. | Count actual service days rather than months, and set the interval on cumulative cooking rather than elapsed time. |
| A tenant on a shared riser in a downtown building | Your line may be light, but the riser is carrying grease from other tenants as well as yours. | Set your interval by the riser, not the canopy, and coordinate through the property manager so the whole run is cleaned at once. |
Do kitchen vents actually need cleaning, or is this optional?
Commercial kitchen vents need professional cleaning on a set interval because the fire code requires it and because the deposit inside them is fuel. It is not a housekeeping preference.
Ontario adopts NFPA 96 by reference through the Ontario Fire Code, O. Reg. 213/07, and the Hamilton Fire Department enforces it across the amalgamated city. A canopy that looks spotless from the cook line tells you nothing about the plenum behind the filters or the duct above it, and those are the parts that carry a flame. Filters catch a share of what comes off the line. Everything they miss goes up.
Insurance is where operators usually feel it first. A carrier asking for proof of maintenance after a claim wants dates, scope and photographs, and a kitchen that cannot produce them is in a weak position regardless of what caused the fire. Residential is a separate question: NFPA 96 governs commercial cooking, so a home range hood is not on an interval at all.
What happens between scheduled cleans
The interval covers the contractor visit. Kitchen staff still have work to do, and it changes how the next visit goes.
Filters are the daily job. Pulled, soaked or run through the dish machine, drained and reseated the right way up, they keep a large share of the grease out of the plenum. A kitchen that handles its filters properly arrives at the scheduled visit in far better shape, and the difference shows in the duct. See the filter cleaning page.
Weekly, wipe the canopy interior and the lip below the filter track. Monthly, walk the roof if the lease allows and check whether grease is escaping onto the membrane, which is a landlord conversation as well as a fire one. Rooftop grease containment covers that.
Some signs mean call early rather than waiting for the calendar. Smoke hanging over the pass. A hood dripping onto the line. A fan that has got louder or is moving less air. Those are set out on the hood vent cleaning page, and booking early costs less than the recovery clean a neglected system eventually needs, priced out on the cost guide.
Keeping a record an inspector or an insurer accepts
A cleaning you cannot evidence counts for very little when somebody official asks. Three documents do the work.
Keep a signed certificate for every visit that names the standard and lists which surfaces were cleaned. Keep the before-and-after photographs of each of those surfaces, because that is what shows the duct interior rather than the parts on display. And keep proof the contractor carried WSIB coverage and liability insurance on the day.
File them by date in one place, digital is fine, and keep the full history rather than the last visit. An inspector wants to see the interval being held over time, and a procurement officer at a campus or hospital kitchen wants the same thing.
Every Hamilton Hood Cleaning job ends with the certificate and the photo report as standard, and insurance proof is supplied before work begins. To set an interval for your kitchen, book a free walk-through through the contact page or call 289-796-0840.
Cleaning frequency: frequently asked questions
What operators ask once the schedule becomes a real decision.
How often should a kitchen exhaust system be cleaned?
Cooking volume sets it. Solid fuel is monthly, high volume quarterly, moderate volume semi-annual and low volume annual under NFPA 96. Most Hamilton restaurants running a fryer and a grill through a full week fall in the quarterly or semi-annual band. The safest way to place a specific kitchen is a walk-through that looks at the equipment, the hours and the state of the plenum.
Can I stretch the interval if the kitchen looks clean?
No, and the canopy is the wrong evidence. The interval is set by accumulation across the whole system, most of which sits in the plenum and the duct where nobody looks. A kitchen that wants a longer interval should ask the contractor to document the duct interior at the next visit and let that make the case.
Who decides the interval, the contractor or the fire department?
The standard sets the categories, the operator is responsible for meeting them, and the Hamilton Fire Department is the authority having jurisdiction that can require proof. A contractor recommends a category based on the cook line and the state of the system. If an inspector disagrees, the inspector wins.
Does a kitchen that closes for part of the year still need cleaning?
Yes. Grease left in a duct over a closed season hardens rather than stabilises, and the next clean costs more as a result. A seasonal kitchen is best served by a clean at the close of the season, plus a mid-season visit if the line runs daily. Idle time is not clean time.
What if the last cleaning date is unknown?
Treat the system as overdue and book a walk-through. An unknown history usually means hardened deposit, which changes both the duration of the first visit and its price. Once that clean is done and documented, the kitchen has a dated record to schedule from.