Kitchen exhaust cleaning frequency is set by how the kitchen actually cooks, not by a single calendar rule. Confirm with your AHJ.
NFPA 96 Hood Cleaning Frequency: How Often Kitchen Exhaust Must Be Cleaned
Grease in a kitchen exhaust system is one of the most reliable causes of commercial structure fires. NFPA 96 ties frequency to cooking volume and fuel type, so two restaurants on the same street can sit on different schedules.
Inspection schedule, not a cleaning schedule
Most guidance online gets this backwards. NFPA 96 Table 12.4 sets an inspection schedule. Cleaning is triggered separately, by 12.6.1.1, when an inspection finds grease accumulation that warrants it.
In practice most operators clean on the inspection cadence and AHJs treat it that way. If a frequency gets challenged, that's the distinction that matters. Clause numbers move between editions too, so check the one your AHJ adopted in NFPA's codes and standards library before citing it.
The frequency schedule
- Monthly: systems serving solid fuel cooking operations (wood, charcoal).
- Quarterly: high-volume operations, meaning 24-hour cooking, charbroiling, or wok cooking.
- Semi-annually: moderate-volume operations. This covers most standard restaurants.
- Annually: low-volume operations — churches, day camps, seasonal businesses, senior centers.
These are minimums. If an inspection finds grease before the next scheduled cleaning, clean it then. The schedule doesn't override what the system looks like.
A barbecue place adds a wood-fired smoker in the spring and nobody updates the service record. The account has run semi-annual since it opened on gas. Six months later the tech pulls the access panel and the horizontal run is loaded well past anything semi-annual should show. That system went solid fuel the moment the smoker landed, which means monthly. The schedule should have moved with the equipment.
What "cleaned" means
NFPA 96 requires cleaning to bare metal where accessible: hood, filters, ductwork, and fan. Surfaces that can't be reached have to be noted. Skip the horizontal duct run because there's no access panel and the honest record is a deficiency plus a recommendation to install panels. Writing that up as a completed cleaning is what burns a contractor later.
What the report must contain
After cleaning, NFPA 96 expects a record showing the date, the company and person who did the work, and any areas that weren't cleaned and why. A certificate or sticker goes on the hood with the date and next due date.
That "areas not cleaned" line is the one most often left blank. It's also the first thing an inspector or insurance adjuster reads after a fire.
Inspection vs cleaning
The system is inspected at the intervals above to see whether cleaning is needed. It's cleaned whenever that inspection finds grease warranting it. Document the inspection even when no cleaning follows. An inspection with no record looks identical to one that never happened.
Common deficiencies
- Cleaning frequency set by habit rather than actual cooking volume
- Solid fuel operations on a quarterly or semi-annual schedule instead of monthly
- Ductwork inaccessible, never cleaned, and never reported as such
- No before-and-after photographs, so nothing proves the work was done
- Certificate missing from the hood or showing an expired date
- Filters cleaned but the fan and duct left untouched
Frequently asked questions
Who decides which frequency applies?
The cooking operation determines it, the AHJ enforces it. Document your reasoning for the interval you're on.
Does the hood need cleaning if the kitchen barely operates?
Yes. Low-volume operations still require annual cleaning at minimum.
What proves the cleaning happened?
The written report plus photographs. Insurers routinely ask for both after a kitchen fire.
Software built for kitchen exhaust cleaning
Essential is all-in-one kitchen hood cleaning software: frequency set per site by NFPA 96 class, before-and-after photos on the job, an "areas not cleaned" field the tech can't skip, and the certificate issued before the truck leaves. It also covers kitchen suppression system inspections for the same customer.
If your frequencies are set by habit rather than by how each kitchen cooks, start there.
