Guide
Grease cup / containment at rooftop fan — inspection points
Grease that gets past the filters still leaves the building through the fan. On an upblast rooftop fan, that grease has to land somewhere controlled — not on the roof membrane, not as a free drip under the curb. The small grease receptacle (the “cup”) and any listed rooftop containment pad are different layers of the same problem. Missing or overflowing cups show up on fire walks and on landlord roof claims.
Short answer
Secondary NFPA 96 / IMC summaries require upblast fans to drain to a readily accessible, visible grease receptacle not over 1 gal (≈3.8–4 L). Rooftop terminations also need a way to drain traps/low points into a noncombustible, closed, rainproof, structurally sound collection container that does not hurt fan performance — with listed grease-collection systems commonly cited under UL 710A. Inspect: cup present and sized, drain not clogged, cup not overflowing, hinge/hold-open so the fan can be opened, roof staining around the curb, and whether a larger containment pan is present when the site needs it. Emptying the cup is part of maintenance; it does not replace a duct/fan clean. Your AHJ’s adopted edition wins.
Inspection points (walk the roof)
| Point | What “good” looks like | Common miss |
|---|---|---|
| Grease receptacle present | Cup/can under the fan drain; visible without dismantling the fan | No cup; open coffee can; missing after last windstorm |
| Size ≤ 1 gal | Secondary NFPA 96 §8.1.2.3 / IMC 511.1.1: max ~1 gal (3.8–4 L) | Oversized open drum that becomes a grease fire can |
| Accessible + visible | Staff or cleaner can empty it without cutting roofing or removing the fan | Cup buried behind curb flashing or under a locked cage with no key |
| Drain path clear | Fan drain tube points into the cup; not pinched, iced, or painted shut | Grease weeping from housing seams because the drain is blocked |
| Not overflowing | Cup below rim; no ring of grease on the roof around the curb | Black halo on membrane = unpaid overflow history |
| Closed / rainproof container | For rooftop termination collection (§7.8.2.1 secondary): closed, rainproof, noncombustible | Open bucket that fills with rain and overflows diluted grease |
| Doesn’t choke the fan | Collection gear clear of the airstream / blade path | Makeshift pans jammed against the discharge |
| Listed containment (when used) | UL 710A–style rooftop grease collection system where the site uses a pad/tray system | Random tarp or plywood “containment” |
| Hinge / hold-open | Fan can tip for blade/housing clean so the drain and cup can be serviced properly | Welded fan — cup never checked because the housing never opens |
Cup vs larger rooftop containment
Think of two layers (secondary vendor and code summaries):
- Fan grease receptacle — the small drain cup under the upblast fan (≤1 gal). Every upblast fan should have this path.
- Rooftop grease collection / containment system — a larger listed pad or enclosure under/around the fan curb that catches what the cup misses and protects the roof. Secondary NFPA 96 §7.8.2.1(4)–(6) language covers draining traps into a proper container and listed collection systems (UL 710A commonly cited).
Having a pretty containment pad does not excuse a missing or overflowing 1-gal cup. Having a cup does not mean the roof is protected if grease is still staining the membrane.
Inspection-ready roof
- Cup present, ≤1 gal, emptyable, under the drain
- No grease halo on the roof; curb flashing intact
- Hinge works so the cleaner can open the fan and photo the blades
- Report names “rooftop fan + grease receptacle / containment”
Common write-ups
- No receptacle — grease streaking down the curb
- Cup full to the brim or kicked over
- Open rain-catch bucket sold as “containment”
- Clean sticker on the hood, zero photos of the roof
Field checklist (send yourself this list)
- Photo set — curb, drain tube, cup (with lid if any), roof staining radius, hinge side
- Empty & weigh risk — if the cup is heavy/full every week, grease load or filter bypass is high; fix filters and schedule, don’t just buy a bigger open can
- Ask the cleaner in writing — “Is the grease receptacle emptied and photographed? Is containment listed / present?”
- Landlord angle — roof staining photos protect you in CAM / damage disputes; keep them with the cleaning report
- Don’t confuse jobs — emptying the cup ≠ cleaning duct interiors to bare metal
Who it’s for / not for
- For: GMs and facilities leads walking the roof after a clean, landlords reviewing tenant reports, operators who keep getting “grease on roof” notes
- Not for: designing a UL 710A system yourself, inventing containment product rankings, or treating cup emptying as the whole NFPA 96 clean
Sources
- UpCodes — Exhaust fans for commercial cooking (IMC 511.1) (code text mirror; upblast drain to ≤1 gal / 4 L receptacle; cites NFPA 96:8.1.2)
- HoodFilters — NFPA 96 rooftop containment excerpts (secondary; §7.8.2.1(4)–(6) collection container; §8.1.2.3 ≤1 gal receptacle)
- HoodFilters — NFPA 96 excerpts (2024) (secondary; same rooftop termination + upblast drain language; UL 710A listing hook)
- US Made Supply — NFPA 96 kitchen exhaust overview (secondary; fan inspection row: grease drain/receptacle + rooftop containment)
- Kitchen Patrol — NFPA 96 regulation notes (secondary; §8.1.2.3 receptacle; owner responsibility framing)
Next step
Next clean day, climb with the crew (or demand roof photos). If there is no ≤1 gal cup under the drain, or the roof has a grease halo, put that on the report and fix it before the next AHJ visit — don’t call the canopy wipe “done.”