We clean hoods and exhaust systems on food trucks and food trailers, and we provide the documentation fire departments ask for. Pricing depends on hood length, duct run and how long it has been since the last clean, so we quote after we know what we are looking at rather than posting a number that would be wrong for half of you.
This page explains what the code actually requires, which is different from what most operators are told.
The Famous “Quarterly Cleaning” Rule Is Not What People Think
Two corrections, both of which change what you should be doing.
First, the schedule everyone quotes is an inspection schedule, not a cleaning schedule. NFPA 96 section 12.4 requires the entire exhaust system to be inspected for grease buildup by a properly trained, qualified and certified person acceptable to the authority having jurisdiction, on the frequency in Table 12.4.
| Type or volume of cooking | Inspection frequency |
|---|---|
| Solid fuel cooking operations | Monthly |
| High volume cooking operations | Quarterly |
| Moderate volume cooking operations | Semiannually |
| Low volume cooking operations | Annually |
High volume means 24 hour cooking, charbroiling and wok cooking. Low volume covers churches, day camps, seasonal businesses and senior centers. So the answer to “how often do I need this done” depends on what you cook, not on a single universal number.
Second, cleaning is triggered by measurement, not by the calendar. NFPA 96 12.6.1.1 requires a measurement system of deposition to decide when cleaning is needed. The thresholds are specific:
- 0.078 inch (2000 micrometres) of deposit on a surface and it must be cleaned, under 12.6.1.1.3
- 0.125 inch (3175 micrometres) in a fan housing and it must be cleaned, under 12.6.1.1.4
- Depth is measured with a grease depth gauge comb, 12.6.1.1.2
And 12.6.2 adds the catch all: cleaned before surfaces become heavily contaminated with grease or oily sludge, whatever the interval says.
“Cleaned to Bare Metal” Is Marketing. Here Is the Real Standard
Bare metal is not NFPA language. The actual requirement, NFPA 96 12.6.1.1.1, is to remove combustible contaminants to a maximum of 0.002 inch, which is 50 micrometres.
That number is more useful than the slogan, because it is measurable and it is what a serious contractor is working to. If a cleaning company cannot tell you what standard they clean to, that is worth noticing.
Changing the Filters Is Not Hood Cleaning
This is the most common shortcut and it does not satisfy anything. The code names the components: hoods, grease removal devices, fans, ducts and other appurtenances, in 12.6.1.1.1 and 12.6.2, and section 12.4 says the entire exhaust system. Filters are the grease removal device. They are one of five named items.
Some related obligations that swapping filters cannot cover:
- 12.6.18 grease removal devices that are broken, distorted or missing components must be replaced, not just cleaned
- 12.6.17 metal containers collecting grease drippings inspected or emptied at least weekly
- 12.1.2 the system must not be operated with filters removed
- 12.7.2 grease collecting below, behind or in the flue gas exhaust of griddles, fryers and charbroilers is a separate cleaning obligation in its own right
That last one matters on a food truck, where everything is packed tight and the space behind a fryer is exactly where grease accumulates unseen.
The Paperwork Is Half the Job
NFPA 96 requires two written reports, and the second one contains the item that tells you whether your contractor is being straight with you.
- 12.6.14 a written inspection report to the owner within 2 weeks, recording where grease exceeds the limits, areas that were inaccessible and therefore not inspected, areas accessible but not inspected, duct access panel locations, visible ductwork leakage, and leaking access panels
- 12.6.15 a written cleaning report within 2 weeks, recording the date, who performed the cleaning, and the company name, address and phone, and detailing areas that were not cleaned and why
- 12.6.16 where required, both reports go to the authority having jurisdiction
The “areas not cleaned” disclosure is the most under used lever in this whole area. A report that lists nothing as inaccessible is usually not a thorough report, and on a truck it is often the thing that reveals there are no duct access panels to clean through. We list what we could not reach and tell you what it would take to make it reachable.
How the Work Is Supposed to Be Done
These are code requirements about the cleaning process itself, and they are a fair way to judge any contractor you hire.
- 12.6.3 electrical switches that could be accidentally activated are locked out before work starts
- 12.6.4 suppression system components must not be rendered inoperable during cleaning
- 12.6.6 flammable solvents or cleaning aids must not be used
- 12.6.7 cleaning chemicals must not be applied to fusible links or other detection devices
- 12.6.8 after cleaning, the system must not be coated with powder or any other substance
- 12.6.9 and 12.6.12 all access panels and cover plates restored, all electrical switches and components returned to operable state
Point 12.6.7 is the one that causes expensive damage. Degreaser sprayed over fusible links can affect the detection system your suppression relies on. It is a fast way to turn a cleaning bill into a suppression bill.
Hood Certification and Getting Signed Off
Hood certification is not a single national credential. In practice it means the inspection and documentation your fire department requires before it will let a mobile unit operate, and it varies by jurisdiction, which is why an operator working several cities ends up doing this more than once.
What a fire department is typically looking at on a mobile unit, beyond the hood itself: the suppression system’s UL 300 listing and current service tag, hood and duct cleaning records, propane system and permit, Class K extinguisher, clearances and separation distances, wheel chocks, and documented operator training.
Colorado operators got a useful change on 1 January 2026. Under HB 25-1295 a valid fire safety permit is honored in other Colorado jurisdictions if it was issued by a local government that has adopted the most recent International Fire Code, or a code incorporating the state Division of Fire Prevention and Control’s minimum standards, and if it followed an inspection by a certified fire inspector. You still have to notify each jurisdiction electronically at least 14 days before operating, once per calendar year, and you are still subject to local inspection. Fail one and the reciprocal permit is void there until you pass a re-inspection.
If You Operate in Denver
Denver requires cleaning documentation to live on the vehicle, and this is a spot check item. The Fire Prevention Division policy states that the exhaust hood, ventilation system and filters must be kept clean and operational, that cleaning must be performed at a minimum each quarter, and that a logbook for the cleaning must be kept on the vehicle and be readily available for inspectors.
One honest caveat. Denver’s inspection checklist applies the International Fire Code’s volume based tiers instead, which give three months for high volume, monthly for solid fuel and six months for other operations. Denver’s policy and its checklist give different answers. We build to the stricter quarterly schedule with an on vehicle logbook, because that satisfies both readings, and we would suggest confirming with the Denver Fire mobiles inspector which one governs your operation.
Missing hood cleaning documentation or excessive grease is on Denver’s list of critical safety spot check violations, which are permit revocable. The logbook is not optional paperwork.
Why This Matters Beyond Compliance
The fire data is worth stating carefully, with its dates attached, because it is usually quoted without them. NFPA found cooking equipment involved in three out of five structure fires in eating and drinking establishments, in data covering 2006 to 2010. The US Fire Administration, using national incident data for 2007 to 2009, estimated about 5,900 restaurant building fires a year with cooking the leading cause at 59 percent.
Both datasets are real and both are dated, and neither is specific to mobile units. We are not going to pretend there is a current mobile food truck fire statistic, because we could not verify one. What is not in doubt is the mechanism: grease accumulates in the parts of the system you cannot see, and a flare up in a hood with heavy deposits behaves very differently from one in a clean hood.
Get It Booked
Call or text 719-722-2537. Tell us your hood length, what you cook, and when it was last done. If it has been a while, say so, it changes the job rather than the welcome.
Most operators should do this alongside their fire suppression inspection at $300 and their LP gas pressure test at $350. One visit, one set of paperwork, one day off the road.
References are to NFPA 96 (2021 and 2024 editions), the International Fire Code, Denver Fire Prevention Division published policy, NFPA structure fire data for 2006 to 2010, and USFA data for 2007 to 2009. Your authority having jurisdiction has the final say. Verified September 2026.