How Are Kitchen Hoods Cleaned?
A commercial hood cleaning is a scheduled overnight visit in which a crew strips grease from a kitchen's entire exhaust path and documents each surface before and after. It runs in phases: arrival and walk-through, electrical isolation, containment, filter removal, canopy and plenum, duct run, rooftop fan, rinse and dry, handback, and paperwork. This page describes what that looks like from the doorway, for an operator who has booked one and wants to know what the night involves rather than how to do it.
What happens when a hood cleaning crew arrives?
The first hour of a Barrie Hood Cleaning visit produces no visible cleaning at all. It is a walk-through, an isolation, and a great deal of plastic sheeting.
The crew usually lands after last service, once the line has cooled and the closing staff are finishing. The lead walks the system with whoever is holding the keys: how many canopies, what sits under each one, where the duct goes after it leaves the plenum, whether roof access is through a hatch or up an exterior ladder, and whether the roof is shared with other tenants. That last question matters more than it sounds, because a shared riser changes what the visit can honestly certify.
Then the power comes down and the sheeting goes up. Watching it happen, most operators are surprised by how much of the kitchen disappears under plastic. The cook line vanishes, the floor route between the hood and the exit is covered, and anything portable that touches food is moved or wrapped. The photography starts at this point too, while every surface is still fully loaded, because a before image taken after the first pass proves nothing.
By the time the first container of degreaser is opened, the kitchen looks less like a kitchen than it will at any other point in the night. That is the intended state. Everything after this is recovery toward a food-ready handback.
How is grease actually removed from a canopy and plenum?
Chemistry does most of the work and time does the rest. The crew wets a section, leaves it, and returns to it, rather than attacking it.
The filters come out early and go straight into a soak, so they are being cleaned in parallel with everything else. Behind them sits the plenum cavity, which is where the visit tends to reveal its real condition. From the kitchen floor a canopy can look serviceable while the plenum behind the filter bank holds a deposit thick enough to string when it is touched. Operators watching their first cleaning almost always comment at this moment, because it is the part of the system nobody has ever seen.
The crew applies degreaser and moves on to the next section while it works. Coming back, the softened deposit is agitated and flushed rather than chipped, and heavy areas get a second application instead of a harder scrub. Around the canopy lip and the grease trough the work is slower and more detailed, because that is where drips have run and hardened over months. Stainless surfaces come back to bare metal, not to a polished layer of old grease.
What the operator sees during this phase is a rotation: one section wet and waiting, one being worked, one being photographed. The rhythm looks unhurried and is the reason a visit finishes in a night rather than dragging into morning prep. How long a full visit runs is covered in the guide on hood cleaning duration.
What happens on the roof?
The rooftop fan is cleaned as part of the same path, with grease captured on the roof rather than left to track across the membrane.
Part of the crew goes up while the interior work is dwelling. The fan is opened or hinged back, the housing and wheel are cleaned, and the top of the duct is worked from above so that the interior team and the roof team meet in the middle of the run. Capture matters here as much as cleaning: grease and wash water that reach a roof membrane become a maintenance bill for whoever owns the building, and on a multi-tenant plaza that conversation lands on the tenant who was cleaning.
Barrie adds a season to this. From December through March a rooftop unit can sit under packed snow and ice, and a fan that was never fitted with a hinge kit is close to unserviceable in a January wind coming off Kempenfelt Bay. That is why rooftop work here gets pulled forward of freeze-up wherever the schedule allows, rather than being pushed into the months that make it hardest. When a fan genuinely cannot be reached safely on the night, it is recorded as not accessible on the paperwork. It is not quietly signed off, because a certificate covering a fan nobody opened is worth less than no certificate at all.
Where grease reaching the membrane is a recurring problem rather than a one-night one, a containment unit at the fan is the durable answer. That is described on the rooftop grease containment page.
How long does each phase take?
A single-hood restaurant visit runs through nine phases in a night. The table describes each one and what the operator sees while it happens.
| Phase | What happens | Share of the night | What the operator sees |
|---|---|---|---|
| Arrival and walk-through | System walked with the operator, roof access and duct route confirmed, shared riser identified | Short opening block | Questions, a clipboard, and someone looking at the ceiling more than the stove |
| Isolation | Electrical supply cut and confirmed dead before anything is opened | Minutes | The fan noise stops, which is often the quietest the kitchen has been all day |
| Containment | Cook line and floor path sheeted, food-contact items moved or wrapped, capture point set | Early block, larger than expected | The line disappearing under plastic |
| Filters out | Baffles pulled and put straight into a soak so they clean in parallel | Brief | The filter bank empty, and the plenum visible behind it for the first time |
| Canopy and plenum | Degreaser applied, left to dwell, agitated and flushed, heavy areas repeated | The largest interior block | Stainless coming back to bare metal, and usually a comment about the plenum |
| Duct run | Worked section by section through the access panels, top and bottom teams meeting in the middle | Varies with the length of the run | Panels open, lights inside the duct, photographs taken through each opening |
| Rooftop fan | Fan opened or hinged back, housing and wheel cleaned, grease and runoff captured on the roof | Runs in parallel with interior dwell time | Half the crew missing for a stretch, then roof photos on the report |
| Rinse, dry, reassemble | Surfaces rinsed and dried, panels resealed, filters refitted the right way around, power restored | Late block | The fan running again, which is the signal the cleaning is finished |
| Handback and paperwork | Sheeting removed, floors returned non-slip, photo set completed, certificate signed on site | Final block before the crew leaves | A working kitchen, a photo report, and a signed certificate in hand |
A single-hood commercial visit runs from $385 and covers every phase above. Multi-hood kitchens run from $725, with club, campus, and multi-tenant sites quoted after a free walk-through.
What does the operator receive at the end?
Two records, both finished on site: a before-and-after photo set of every cleaned surface, and a signed health and safety certificate referencing NFPA 96.
The photo set is deliberately unglamorous. Each surface is shot from a matching angle before and after, so the change is demonstrated rather than claimed, and the duct images are taken through the access openings that were actually opened. If a section was unreachable, that appears in the record too. An honest gap is useful information. A silent one becomes a problem the first time an inspector opens a panel.
The certificate is the document that gets filed. Barrie Fire and Emergency Service enforces the Ontario Fire Code, and the Ontario Fire Code adopts NFPA 96 by reference, so the question at inspection is whether dated evidence exists that the whole path was cleaned on schedule. The same pair of documents is what an insurance adjuster asks for after a flare-up, which is the moment operators discover whether their previous contractor documented anything.
Before the crew leaves, the next interval goes on the calendar based on the kitchen's cooking volume, and rooftop work gets positioned ahead of freeze-up if the snowbelt would otherwise bury the fan. Which interval applies is set out in the guide on cleaning frequency, and the standard behind it on the NFPA 96 page. Anyone wanting the method rather than the narrative should read how kitchen exhaust fans are cleaned.
Inside a hood cleaning: frequently asked questions
What operators ask the week before their first booked visit.
Does the kitchen have to close for a hood cleaning?
No. Barrie Hood Cleaning schedules restaurant work overnight, starting after last service and finishing before morning prep, so the kitchen never loses a trading hour. Golf and banquet kitchens are booked between events, and campus serveries are done during March break, reading week, or the summer term while the servery is dark. The building is handed back food-ready rather than as a job site.
What does the crew do before any cleaning starts?
The first phase is entirely preparation. The crew walks the system with the operator, confirms roof access and where the duct runs, isolates the electrical supply, and then sheets the cook line and the floor path so that no degreaser or runoff reaches a food surface. Before-and-after photography also starts here, because the before images are taken while everything is still loaded.
Is the roof always part of the job?
On a full kitchen exhaust cleaning the rooftop fan is part of the path and is cleaned with everything else. In a Barrie winter that is not always possible, because a fan can sit under packed snow and ice from December through March and a unit without a hinge kit is close to unserviceable in a wind off Kempenfelt Bay. Rooftop work is therefore pulled forward of freeze-up where the schedule allows, and anything genuinely unreachable on the night is recorded as not accessible rather than certified.
What does the operator receive at the end?
Two records, both completed on site. The first is a before-and-after photo set of each cleaned surface, shot from matching angles so the change is visible rather than asserted. The second is a signed health and safety certificate referencing NFPA 96. Those two documents are what Barrie Fire and Emergency Service asks to see, and they are also what an insurance adjuster requests after a flare-up.
How does the kitchen look the next morning?
It looks like a kitchen, not a work site. The final phase is a handback: tarps and sheeting removed, every surface that met degreaser rinsed and wiped, floors returned to non-slip, and filters reinstalled the right way around so they drain into the trough. The morning crew should be able to start prep without cleaning up after anyone.