Hood Cleaning vs. Duct Cleaning vs. Exhaust Fan Cleaning: What Each One Actually Covers

When a Toronto restaurant operator gets quotes from three different hood cleaning contractors, they often get three different price ranges, and three different definitions of what’s actually being cleaned.

Some contractors quote “hood cleaning.” Some quote “hood and duct cleaning.” Some quote “full exhaust system cleaning.” The pricing varies. And here’s the catch: each phrase can mean different things to different contractors.

Under NFPA 96, there’s only one standard. The exhaust system has multiple components, and a compliant cleaning covers all of them. Here’s what each component is, what cleaning it actually involves, and why partial cleanings leave you exposed.

The components of a commercial kitchen exhaust system

Working from the cookline upward and outward, your exhaust system has six distinct components.

The hood. The metal canopy directly above your cooking equipment. This is the visible part, the part everyone thinks of when they say “hood cleaning.” It catches the initial vapor and grease from cooking.

The grease removal devices. Inside the hood, mounted at an angle, are filters or baffles. These are the first line of defense. They capture the heaviest grease particles before vapors enter the rest of the system. Filters are removable and typically soaked in degreaser as part of every cleaning.

The plenum. The chamber above the filters where vapors collect before being pulled into the duct. This is where most grease accumulates first and fastest because vapors slow down as they enter this larger space. The plenum is hidden behind the filters and is one of the most commonly skipped areas in partial cleanings.

The duct. The metal pipe (typically galvanized steel) that runs from the plenum up through the building and out to the roof. Ducts can be 10 feet long in a one-story building or over 100 feet in a high-rise. They typically have multiple bends and elbows. Grease that escapes the filters and plenum coats the duct interior along its full length.

The exhaust fan. Mounted at the duct discharge, usually on the rooftop. The fan pulls air through the entire system. Its blades, housing, and motor compartment accumulate grease over time. The fan itself is a significant fire risk because it generates heat from motor operation and is exposed to outdoor temperature swings that affect grease behaviour.

The rooftop grease containment. A pan or curb system around the exhaust fan designed to catch grease that drips from the discharge. This area also accumulates wind-blown dust, leaves, and other debris that can interact with grease deposits.

What NFPA 96 considers a complete cleaning

NFPA 96 does not recognise hood-only cleaning. The standard applies to “hoods, grease removal devices, fans, ducts, and other appurtenances,” and requires those surfaces to be cleaned to remove combustible contaminants, meaning all six components above are in scope at each service, not just the one you can see. We clean them to bare metal, which is past what the standard sets as the threshold and the only outcome a photograph can verify.

A complete cleaning under NFPA 96 includes filters removed and soaked in degreaser solution; hood interior scraped, pressure washed, and dried; plenum opened (this requires removing access panels above the filters) and cleaned to bare metal; duct interior accessed at all available access points along the run and cleaned to bare metal, with code-compliant contractors installing access panels where they don’t exist; exhaust fan disassembled with fan blades, housing, motor compartment, and discharge openings all cleaned to bare metal; rooftop grease containment cleaned and the surrounding area inspected for residue; and photo documentation of each component, before and after.

That’s what NFPA 96 requires. Anything less than that is, by definition, non-compliant.

Where partial cleanings fall short

The most common shortcut is “hood cleaning” that’s actually just the hood interior. This is the cheapest version contractors offer, and it’s usually priced to look like a bargain. It removes the filters, soaks them, wipes down what’s visible from below, and rehangs the filters. The plenum, ducts, and fan are not touched. Cost is low. Compliance is zero.

A step above that is “hood and filter cleaning” with no duct access. It still misses the plenum (or only does a token wipe of the accessible portion) and skips the entire duct run. The fan may or may not be opened depending on rooftop access. Cost is moderate. Compliance is still incomplete.

Then there’s “full cleaning” without photos. Some contractors do clean the full system but don’t provide photo documentation. The cleaning itself may be compliant, but without before-and-after photos, you have no way to prove it after a fire or during an audit. Your insurer treats this the same as a non-compliant cleaning.

Why you can’t tell from underneath

Here’s the part that catches most operators: standing in your kitchen and looking up at the hood, you can’t tell whether the plenum, duct, or fan was actually cleaned. The visible underside of the hood looks the same either way. The filters look clean either way.

The only way to verify a complete cleaning is photo documentation of every component. If the photos don’t show the plenum interior, the duct interior at access points, and the fan disassembled, that part of the system wasn’t cleaned.

What to ask your contractor

If you’re evaluating a hood cleaning contractor (current or prospective), four questions distinguish a complete service from a partial one. Do you clean the plenum, ducts, and exhaust fan on every job, or only when requested? Do you provide before-and-after photos of all those components within 24 hours of service? If my ducts don’t have access panels, do you install them as part of compliance work? Can I see a sample photo set from a recent job, with the customer’s name redacted?

Compliant contractors answer all of these affirmatively and confidently. Non-compliant contractors hedge.

What full-system cleaning actually costs

What full-system cleaning costs depends on the size and complexity of the system: one hood with a short duct run and a single rooftop fan is a very different job from a multi-hood kitchen with long horizontal runs and awkward roof access. The useful thing to know is that the gap between hood-only pricing and full-system pricing is usually smaller than operators expect, while the compliance gap between them is the difference between a paid insurance claim and a denied one. Get both scoped in writing before you compare.

We provide complete NFPA 96 cleaning on every job (hood, plenum, ducts, fan, and rooftop) with before-and-after photo documentation of each component. If you’re not sure what your current contractor is actually cleaning, we’ll come walk your system for free and show you what’s been getting missed.

Book Free On-Site Evaluation or call 647-749-0045