Every hour your line runs, a thin film of vaporized grease travels up the hood, through the duct, and out the fan on the roof. None of it burns while it is cold. All of it burns at once if something upstream lights it.
Fire & Safety Equipment III LLC has been cleaning commercial kitchen exhaust systems since 1975. Our shop is in Platteville, Wisconsin, and our technicians are based across Wisconsin, Iowa and northern Illinois — 10 service vehicles covering kitchens in all three states. This page explains what a real hood cleaning covers, how often the code says you need one, and what we leave behind for your file.
The Part That Actually Burns
A hood fire almost never starts in the hood. It starts on the cooking surface — an overheated pan, a fryer that ran dry, a flare-up on the char-broiler — and then it finds the one thing in your kitchen that is both flammable and continuous: the grease deposit lining the inside of the exhaust system.
That deposit is not evenly spread. It is heaviest in the hood plenum right behind the filters, it collects in the horizontal duct run where airflow slows, and it cakes on the blower wheel where centrifugal force throws it. Once it ignites, the duct behaves exactly like a chimney: it carries fire from your kitchen into the ceiling space, the roof, or the tenant next door, and it does it faster than anyone on the line can react.
Your suppression system is aimed at the appliances and the plenum. It is not aimed twenty feet down a duct run. That is why cleaning is not housekeeping — it is the other half of the fire protection on that hood.
NFPA 96 in one sentence
The standard requires the entire exhaust system — hood, filters, plenum, duct, and fan — to be inspected for grease buildup on a set schedule and cleaned to bare metal wherever it is accessible. “Wiped down” is not the standard. Bare metal is.
What “Cleaned” Actually Means
There is a version of hood cleaning that takes forty-five minutes, makes the visible stainless shine, and leaves the duct exactly as greasy as it was. It photographs well. It fails an inspection the moment somebody opens an access panel. Here is what we cover on a full cleaning:
- Filters removed and degreased
- Hood interior and plenum
- Vertical duct riser
- Horizontal duct runs
- Exhaust fan housing
- Blower wheel and blades
- Rooftop grease containment
- Stainless polished on the way out
We protect the cooking line and the floor before anything gets wet, apply degreaser hot, scrape what has hardened, wash it down, and dry and polish the exposed surfaces. Access panels get opened and closed properly. Anything we cannot reach — a duct run with no access panel, for example — gets written down and reported to you rather than quietly skipped.
How Often Your Kitchen Needs It
Frequency is not a preference. It is set by what you cook and how much of it, and an inspector will ask you to justify the interval you are on.
Monthly
Solid fuel
Wood-fired and charcoal cooking. The heaviest deposit rate of anything on this list, and the only category that also puts embers into the duct.
Quarterly
High volume
Twenty-four-hour operations, heavy char-broiling, wok cooking, and high-output fryer lines. If your kitchen never really stops, you are here.
Semiannual
Moderate volume
The typical sit-down restaurant, bar and grill, school kitchen, or hotel line. This is where most of our accounts sit.
Annual
Low volume
Churches, seasonal kitchens, day camps, and places that only fire the line for events. Low volume is not no volume — the schedule still applies.
Ongoing
Your filters
Baffle filters should come out and go through the dish machine or a soak tank regularly — often nightly in a busy kitchen. Filters that stay loaded push grease straight past the hood and into the duct, which shortens everything else on this list.
The Fan Nobody Looks At
The exhaust fan sits on the roof, out of sight, doing the hardest work in the system. When the blower wheel loads up with grease, three things happen at once: airflow drops so smoke and heat hang in your kitchen, the motor works harder and runs hotter, and the wheel goes out of balance and starts to vibrate. The vibration is what eventually takes out the bearings.
We clean the fan housing and the wheel itself, not just the outside of the curb. If your fan has no hinge kit, it has to be unbolted and lifted every single cleaning — which is slow, which is expensive, and which is why some cleaners quietly skip it. A hinge kit lets the fan tip back in seconds, and it pays for itself over a couple of visits. We can install a hinge kit on most rooftop exhaust fans, and we will tell you if yours would benefit rather than charging you to wrestle it every time.
While we are up there we also check the grease containment — the box or pad that catches what the fan throws off. A saturated containment sends grease straight onto your roof membrane, which turns into a slip hazard, a roofing bill, and in a leased building, a conversation with your landlord.
What We Leave in Your File
The cleaning is half the job. The documentation is the half that matters when someone official is standing in your kitchen.
After every visit you get a dated service sticker on the hood, a written report of what was cleaned, and a note of anything we could not access or anything we found that needs attention — a missing filter, a damaged access panel, a duct with no cleanout. Those records need to stay on site, and inspectors do ask for them.
If your insurance carrier requires proof of a cleaning schedule, this is what satisfies them. If a fire ever does happen, it is also what demonstrates you were maintaining the system as required — which is not a small thing when a claim is being reviewed.
One Company, Two Crews
A hood has two fire-protection systems on it: the suppression system that puts a fire out, and the cleaning schedule that keeps there from being much to burn. They are usually handled by two different vendors on two different schedules, and the gaps between them are where problems live.
We do both, but not with the same people. Hood cleaning is done by our cleaning crew; the semiannual suppression inspection is done by our suppression technicians. That means two appointments rather than one — we will schedule them close together if you want — but it is one company, one phone number and one set of records covering both, and nobody pointing at the other guy when something gets missed.
We also handle extinguisher inspections and extinguisher service for the same kitchens, so the whole back of house still comes down to one call.
What NFPA 96 Actually Requires
Hood cleaning is one of the few services where the code tells you the frequency, the method, the paperwork and the people. NFPA 96, the Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations, is adopted into the fire codes of Wisconsin, Iowa and Illinois, and its Chapter 12 on inspection and maintenance is what your fire inspector and your insurance carrier are both reading from. Here is the substance of it.
Inspection frequency by cooking volume
The exhaust system — hood, filters, ducts and fan — must be inspected for grease buildup by a properly trained, qualified and certified person on a schedule set by what you cook and how much: monthly for solid-fuel cooking such as wood or charcoal; quarterly for high-volume operations like 24-hour restaurants, charbroiling and wok cooking; semiannually for moderate-volume operations, which covers most restaurants, schools and institutional kitchens; and annually for low-volume operations such as churches, day camps, seasonal businesses and senior centers.
Cleaning, method and documentation
When the inspection finds grease deposits, the entire exhaust system must be cleaned — hood, ducts, fan and every accessible surface — down to bare metal. Flammable solvents and cleaning aids are prohibited, and the cleaning company may not wash grease down into the fire suppression system, the fan bearings or the roof. After the work, the company must leave a label on the hood showing its name, the date and any areas that were not cleaned, and give the owner a written report that lists the areas not cleaned and why, so that the owner can address them.
Ducts, access panels and hinged fans
NFPA 96 requires the duct system to be built for cleaning: access openings at every change of direction and at intervals along horizontal runs, sealed with listed access panels; and rooftop upblast fans hinged so they can be swung open without disconnecting the electrical service, with a hold-open retainer to keep them from falling. Ducts that cannot be reached cannot be cleaned, which is why “not cleaned” on a report is often an access problem rather than a cleaning problem — and one we can fix by installing panels.
The other half: filters, the fan and the suppression system
The standard also requires grease filters to be listed, kept in place at all times during cooking, and cleaned or replaced before they clog; mesh filters that are not listed are not acceptable. The exhaust fan must run whenever the cooking equipment is on, and fans with grease-heavy accumulation are a fire risk on their own because they sit on the roof, out of sight. Finally, NFPA 96 Chapter 10 requires the hood and appliances producing grease-laden vapors to be protected by an automatic fire suppression system that is inspected and serviced semiannually under NFPA 17A — a separate appointment with our suppression technicians, scheduled alongside the cleaning. Cleaning the exhaust system without maintaining the suppression system, or the reverse, leaves half of the code unmet.
What Wisconsin, Iowa and Illinois require
In Wisconsin, Wis. Admin. Code ch. SPS 314 adopts NFPA 1, the Fire Code, for every public building and place of employment; NFPA 1’s commercial cooking chapter requires cooking operations to comply with NFPA 96, including the inspection and cleaning schedule. SPS 314 also specifically applies the hood and suppression design requirements to mobile kitchens, so food trucks and trailers operating in Wisconsin are covered. In Iowa, Iowa Admin. Code 481—Chapter 280 adopts the 2024 International Fire Code, whose commercial kitchen hood provisions require hoods, ducts and fans to be cleaned at the intervals in NFPA 96 and require the records of that cleaning to be kept on the premises for the fire code official. Illinois relies on the Office of the State Fire Marshal’s rules and on locally adopted fire codes — in the northern Illinois communities we serve that is typically a local edition of the International Fire Code or NFPA 1, and both point back to NFPA 96. Your local fire department in any of those cities can ask to see the cleaning label on the hood and the report in your file, and they do.
Cooking equipment is the leading cause of structure fires in eating and drinking establishments in NFPA’s national fire statistics, and grease in the exhaust system is what turns a flare-up on the range into a fire in the ceiling. The intervals in NFPA 96 are not arbitrary; they are the schedule that keeps the fuel out of the duct.
- NFPA 96, Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations — National Fire Protection Association
- NFPA 17A, Standard for Wet Chemical Extinguishing Systems — National Fire Protection Association
- Wis. Admin. Code ch. SPS 314, Fire Prevention — Wisconsin Legislature
- Iowa Admin. Code 481—Chapter 280, Fire Control Administration — Iowa Legislature
Since 1975
We started as one man with one truck. In 1985 we bought the old furniture building at 5675 Southwest Rd in Platteville and never left. Fifty years on we are 16 people and 10 vehicles working across Wisconsin, Iowa, and Illinois. We have cleaned hoods in kitchens that have changed hands four times and still call us. Read the full story.
Hood Cleaning Where You Are
Hood cleaning happens after close, which means the trucks are out at hours most vendors will not work. These are the markets we cover most often — pick your city for local details.
Iowa
Wisconsin
Questions We Get Asked
How often does my kitchen exhaust hood have to be cleaned?
It depends on what and how much you cook. Solid fuel is monthly, high-volume kitchens are quarterly, the typical restaurant is semiannual, and low-volume operations are annual. Whatever interval you are on, the system has to be inspected for buildup on that schedule and cleaned to bare metal wherever it is accessible.
Does a hood cleaning include the duct and the rooftop fan?
On our cleanings, yes. Filters, hood interior, plenum, vertical and horizontal duct, fan housing, and the blower wheel itself. If a section of duct has no access panel and genuinely cannot be reached, we document it and tell you rather than leaving it off the report.
Can you work after we close?
That is when most of this happens. The line has to be cold and the kitchen has to be empty, so hood cleanings are usually a late-night or early-morning job. We schedule around your hours, not ours.
How long does it take?
A single hood over a modest line is typically a few hours. A long line with multiple hoods, a long duct run, and a rooftop fan can run most of a night. We will give you a realistic window before we book it, and we would rather quote you honestly than start a job we cannot finish before you open.
What is a hinge kit and do I need one?
It is a hinged mount that lets your rooftop exhaust fan tip back for cleaning instead of being unbolted and lifted every visit. If your fan gets cleaned two or four times a year, a hinge kit makes each cleaning faster and safer, and it usually pays for itself quickly. We will tell you whether yours is a good candidate.
Do you clean the filters, or should my staff?
Both. We degrease them as part of the cleaning, but baffle filters should also be pulled and washed regularly by your team — often nightly in a busy kitchen. Loaded filters push grease into the duct, which makes everything downstream worse.
Will you also service the suppression system on the same hood?
Yes, and we would rather do both. The suppression inspection is done by our suppression technicians on a separate appointment from the cleaning crew, but it is one company, one phone number and one set of records — nothing falls between two vendors.
What areas do you cover?
We run 10 service vehicles with technicians based across Wisconsin, Iowa and northern Illinois, and clean hoods in all three states. If you are not sure whether you are in range, call and ask — we will tell you straight.
Tell us what you have and where you are.
Extinguishers, a kitchen system, a hood, a booth — one visit, one invoice. We reply the same business day.
5675 Southwest Rd, Platteville, WI 53818 · Mon–Thu 8:00–4:30, Fri 8:00–2:00