How Often Does a Commercial Kitchen Hood Need Cleaning?
NFPA 96 sets an inspection interval by how much and what you cook — but cleaning is triggered by measured grease depth, not the date on a contract. Here's how to find your kitchen's real interval.
Most kitchen owners have been told a number. Quarterly, usually, because that is what was on the last contract. The number is not wrong for everyone, but it did not come from your kitchen — and the standard your fire marshal reads does not work the way the contract implies.
The Interval Is an Inspection Interval
NFPA 96 sets a schedule for inspecting the exhaust system, and it assigns that schedule by two things: how much you cook, and what you cook on.
Solid fuel is the equipment question, and it overrides everything else. A wood-fired oven puts the entire system on a monthly interval no matter how quiet the dining room is, because solid fuel produces creosote as well as grease and sends live embers into a duct that is already coated. A charcoal grill falls into the high-volume quarterly tier.
Everything else follows volume. High-volume operations — twenty-four-hour service, charcoal grilling, heavy charbroiling, wok cooking — are inspected quarterly. Moderate-volume kitchens, which is most full-service restaurants, semiannually. Low-volume operations such as churches, day camps and seasonal businesses, annually.
Note what that list is. It is a schedule for looking at the system. It is not a schedule for cleaning it.
The Cleaning Is Triggered by a Measurement
Cleaning is a separate requirement, and what triggers it is grease depth — an actual number, taken with a depth gauge comb placed on the surface.
Where a measured depth of 0.078 in. (2,000 microns) is observed, the surfaces are cleaned. In a fan housing, the figure is 0.125 in. (3,175 microns). And cleaning means cleaning to a maximum of 0.002 in. (50 microns) — not a wipe, a removal of combustible contaminants down to that level.
There is a further requirement that has nothing to do with the gauge: surfaces are cleaned before they become heavily contaminated with grease or oily sludge. A kitchen sitting just under the trigger is not thereby compliant.
That is why a kitchen can be on schedule and still be out of compliance. If the inspection finds grease over the limit, the system is cleaned then — not at the next date on the contract. In a high-volume or solid-fuel kitchen the depth is almost always over by the time the inspection comes around, so the inspection and the cleaning happen on the same visit and the distinction never surfaces. For moderate and low-volume kitchens it surfaces constantly.
What This Means for Your Last Report
Pull it out and look for a number.
A report that gives a date and a list of what was cleaned tells you somebody came. A report that gives a depth reading — before, and after — tells you what they found and what they removed. One is a receipt. The other is a record, and it is the one a fire marshal, an insurance adjuster or a property manager can use.
If there is no number on your report, nobody measured. That is worth knowing before an inspection, not after a fire.
Where the Reading Is Taken
The depth that matters is not at the hood. The hood is the part you can see and the part a wipe-down reaches. Grease travels up the duct and collects at the horizontal runs, the plenum, and the fan on the roof — the part of the system hardest to reach and easiest to skip, and the one with its own threshold.
A complete inspection opens the access panels, reaches the fan, and measures where the grease actually is. If your report shows no photographs of the rooftop fan, ask where the reading came from.
California
NFPA 96 is a standard, not a law. It binds your kitchen because California adopts it through the state fire code, and your local fire authority enforces the adopted version. Local amendments can make the requirement stricter, and your insurance policy can make it stricter again — a protective safeguards endorsement can require maintenance on terms of its own, independent of the fire code.
Three different parties can therefore ask you for the same thing. All three accept the same answer: a dated report with a measurement on it.
What to Do This Week
Work out which interval your kitchen falls under. Start with the equipment: a wood-fired, solid-fuel oven puts you on monthly. Otherwise be honest about volume — charcoal grilling, or a single charbroiler running until close, pushes a kitchen into the quarterly tier.
Then find your last report and check it against that interval, and check it for a depth reading. If the gap is longer than your tier allows, or there is no number on the page, you have found your next call.
Cleaning Pros Plus, LLC measures grease depth on every job, records the reading on the report, and books the next inspection date before leaving the site. We are an IKECA member serving the Central Valley, the Bay Area and Northern California.
Contact Us: cleaningprosplus.com/contact
About the Author
Arthur Haggerty is the founder of Cleaning Pros Plus, LLC and its family of companies — HoodOps and Stovio Advisors. He is a Certified Exhaust System Inspector (CESI #200771) and holds the Certified Exhaust Cleaning Specialist credential (CECS #200452), and Cleaning Pros Plus, LLC is an IKECA member. He has served as an expert witness in an NFPA 96 commercial kitchen fire case. Before founding Cleaning Pros Plus, he spent 25 years in enterprise IT and cybersecurity consulting across industries at Deloitte, Cisco and Dell, including a decade in IT audit and compliance, and holds an M.S. in Information Technology. He is a ten-year U.S. Air Force veteran.