Grease Duct & Exhaust Fan Cleaning: The Concealed 80% of Your Fire Path
Inspectors now look above the filters. We scrape and wash duct runs and fans to bare metal, measure what we find, and install the access panels that make a real cleaning possible — from $599 per cleaning.
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What Grease Duct & Fan Cleaning Covers
Grease duct and exhaust fan cleaning is the duct-level depth of a kitchen exhaust hood cleaning engagement: everything between the hood plenum and open air. Grease-laden vapor leaves the cookline hot, travels the duct, cools, and condenses on duct walls — heaviest at elbows, transitions, and long horizontal runs. The fan at the end of the system collects its own grease load on blades and housing, where it degrades airflow and drips back into the duct.
Service-Tech's duct and fan scope covers:
- Horizontal and vertical duct runs scraped and washed to bare metal
- Elbows, transitions, and diameter changes — the condensation points where grease loads first
- Rooftop and wall-mounted exhaust fans: blades, housing, shroud, and the grease-drainage path
- Hinge-kit and fan-tipping service so the fan can actually be opened and cleaned rather than wiped around
- Access panel installation where the duct run has none, to code requirements
- Grease-depth documentation and photo evidence from inside the duct — not just the parts you can see from the kitchen
Why the Duct Is Where Kitchens Burn
A cookline fire that reaches the hood has one path: up. Once flame enters a grease-loaded duct, it is burning inside a fuel-lined chimney that runs through the building — above the reach of the hood's suppression system, often inside chases and above ceilings where nobody can fight it. This is why duct condition, not hood shine, is what determines whether a small flare-up stays an incident report or becomes a structure fire. It is also why inspectors have learned to lift filters and look up the riser before they look at anything else.
No Access Panels, No Real Cleaning
Here is the technical point nearly every ranking page skips: a duct run can only be cleaned where a human or tool can reach it, and NFPA 96 requires access panels along duct runs for exactly that reason — at changes of direction and at intervals along horizontal runs, so that no section of the system is beyond reach.
The practical consequence for an operator: if your duct has a 40-foot horizontal run with no panels, previous "full system cleanings" cleaned the first few feet from each end and left the middle loaded — regardless of what the sticker said. When we find missing access, we say so on the report, and we install panels to code so the next cleaning is a real one. A duct that cannot be fully accessed cannot honestly be certified as clean; disclosure of areas not cleaned is what separates a professional report from a decorative sticker.
Measured Grease Depth, Not Calendar Guessing
IKECA practice — and the inspection logic NFPA 96 is built on — treats measured grease depth as the objective trigger for cleaning. Our technicians gauge deposit depth at representative points in the system and record the readings, because "it looks dirty" and "it's been six months" are both bad data. Measured depth answers the questions that matter:
- Is cleaning due now? Deposit past the actionable threshold means yes — whatever the calendar says
- Is your frequency class right? A quarterly-cleaned duct that comes up heavily loaded is telling you the operation is running hotter than its schedule assumes
- Did the last vendor actually clean? Depth readings immediately after a "cleaning" are the fastest audit of what you paid for
- Where does your system load first? Reading patterns show which elbows and runs are your early-warning points
You get the readings in your report. Over a few cycles, that record becomes a grease-accumulation profile of your operation — the difference between managing the system and repeatedly discovering it.
Vertical Runs, Rooftop Fans, and Work at Height
Multi-story buildings put grease ducts where cleaning crews don't like to go: vertical risers climbing several floors, terminations on high roofs, fans mounted at the top of exterior wall chases. This is where scope quietly shrinks — vendors clean what is comfortable to reach and the vertical run becomes someone else's problem.
Service-Tech fields crews trained and equipped for elevated work, including rope-access capability on redundant two-rope systems under a documented fall-protection training program, so rooftop fans, upper duct sections, and exterior riser access points stay inside the scope instead of falling off it. On the fan itself, we service hinge kits and tip the unit properly — a fan cleaned "in place" without opening is a fan half-cleaned.
How Ducts Get Cleaned to Bare Metal
- 01
System survey
Duct routing traced end to end, access points mapped, missing panels identified, grease depth gauged.
- 02
Containment
Kitchen and rooftop work areas protected; the duct's contents stay in our collection, not on your equipment or roof membrane.
- 03
Mechanical cleaning
Scraping and washing to bare metal through each access point — elbows, transitions, and risers included, not skipped.
- 04
Fan service
Fan opened on its hinges, blades and housing degreased, drainage path cleared, unit reseated.
- 05
Documentation
Photos from inside the duct, grease-depth readings, deficiencies noted — including any area that could not be accessed and why.
When Duct Cleaning Is Due
Duct and fan cleaning belongs in every compliant cleaning cycle for your volume class — it is not an upgrade to a hood cleaning, it is the part that makes the cleaning mean something. Between cycles, the triggers are inspection findings, measured depth past threshold, visible grease at the fan or roof termination, and airflow decline the cookline crew notices before anyone else does. Filter condition upstream directly sets how fast the duct loads; pair this service with grease filter maintenance programs to slow the accumulation you're paying to remove.
Who Needs Duct-Level Depth
Restaurants first — see restaurant hood cleaning for the operator-facing service — plus the institutional kitchens where duct runs get long and complicated: hospitals, universities, hotels, corporate cafeterias, and stadium concessions across the industries we serve. Long horizontal runs through occupied buildings are precisely where access-panel and vertical-riser discipline pays for itself.
Pricing
Duct and fan cleaning is part of our kitchen exhaust cleaning service, from $599 per cleaning, with final pricing set by duct length and routing, number of vertical risers and fans, access-panel work required, and roof access. Estimates are free; travel is factored into the quote.
What a Concealed Duct Fire Does
A duct fire doesn't announce itself at the hood — it travels. Fire departments fight it through the building, opening chases and ceilings along the run. Even a contained event typically closes the kitchen for weeks between fire damage, duct replacement, and re-inspection. And the post-loss review reads your cleaning records with the specific question of whether the duct — not the hood — was maintained. A documented bare-metal duct program is how that review ends quickly and in your favor.
If your last report has no duct photos and no depth readings, you don't know what's above your filters. —
The Access Requirements That Decide Whether a Duct Can Be Cleaned at All
A grease duct that cannot be reached cannot be cleaned or inspected, and NFPA 96 is specific about what reachable means.
- Personnel entry where possible. On horizontal ducts NFPA 96 calls for at least one 20 in × 20 in opening for personnel entry.
- Otherwise, 12 ft intervals. Where an opening that size is not possible, openings large enough for thorough cleaning are provided at 12 ft (3.7 m) intervals along the run.
- Panels are rated, not improvised. Access panels match the duct material and thickness, seal greasetight, and use a gasket or sealant rated to 1,500 °F.
- Safe access to the opening. Where a panel is not reachable from a 10 ft stepladder, a work platform is required — which is a design item, not something to solve on the day.
- The trigger is still the gauge. A comb-gauge reading of 0.002 in requires the entire system cleaned; 0.078 in means immediately; and NFPA 96 Table 11.4 sets the minimum frequency by cooking volume.
- Then the sequence. Isolate, lock out, shroud the fan, scrape the hardened deposit, degrease, hot-wash, squeegee runoff to containment, reinstate.
Frequently Asked Questions
Isn't the duct included in a normal hood cleaning?
It should be — but "hood cleaning" quotes frequently cover only the canopy, plenum, and filters. Ask whether the price includes duct runs to the fan and the fan itself, and whether the report will disclose inaccessible sections. At Service-Tech, duct and fan are standard scope, cleaned to bare metal and documented with interior photos.
What if my duct has no access panels?
Then no vendor has ever fully cleaned it, whatever their stickers claimed. NFPA 96 requires access panels so every duct section can be reached. We identify missing access during the survey, install panels to code, and disclose any section that still cannot be reached on your report rather than certifying around it.
How do you know when a duct actually needs cleaning?
By measurement. Our technicians gauge grease depth at representative points and record the readings — the objective trigger IKECA practice and NFPA 96 inspection logic are built on. Measured depth tells you whether cleaning is due now, whether your frequency class matches your cooking volume, and whether your previous vendor's work held up.
Do you clean vertical duct risers and rooftop fans?
Yes. Vertical runs and roof terminations are where scope usually shrinks, so we staff for them — including rope-access capability on redundant two-rope systems for elevated exterior access. Fans are opened on hinge kits and cleaned through, not wiped in place; we install hinge kits where they're missing.
What does grease duct cleaning cost?
Kitchen exhaust cleaning starts at $599 per cleaning, with duct length and routing, riser and fan count, access-panel work, and roof access setting the final price. Estimates are free and travel is factored into the quote. Recurring schedules matched to your NFPA 96 volume class keep per-visit costs predictable.