Plain English:
506.5 equipment must be approved or listed and comply with 506.5.1 through 506.5.6.
506.5.1 Type I exhaust fans: Fan housing must be built like a grease duct (see 506.3.1) unless the fan is listed to UL 705.
506.5.1.1 motor location: Motor must be outside the exhaust airstream.
506.5.1.2 in line fan indoors: If an enclosed grease duct connects to an in line fan not outdoors, the fan must be in a room or space with the same fire resistance rating as the grease duct enclosure, with service access and ventilation per the manufacturer.
506.5.2 pollution control units (PCU)
Key checks:
UL 8782 listed PCU, UL 705 listed fan, noncombustible supports, indoor units listed for indoor use, clearances per listing.
If indoors with enclosed grease duct: dedicated rated enclosure space equal to duct enclosure rating, with access and ventilation per manufacturer.
Other must haves: roof mounted units at least 18 in above roof, discharge location per 506.3.13, pressure drop monitoring with a visual alarm in the cooking area when airflow drops below design, factory fire suppression, service clearances, and wash down drains to a grease interceptor with trapped or sealed drain.
506.5.3 discharge and drainage: Discharge cannot impinge on roof, equipment, or structure. Vertical discharge fans need a drain outlet at the low point to an approved grease reservoir.
506.5.4 upblast fan mounting: Hinged fan, flexible weatherproof electrical cable, and a restraint. Grease duct extends at least 18 in above roof.
506.5.5 clearances: 18" to combustibles unless listed for less.
506.5.6 termination: Must meet 506.3.13.
Parapet exception: 2 ft minimum if parapet is not higher than the top of discharge opening.
On Plans: Why it matters
Redlines usually come from missing hinge and service access, no grease drain to reservoir, motor shown in the airstream, discharge blasting the roof, or PCU alarms and drains not detailed.
Code Path: Where to show it
M-001: Type I exhaust equipment note for UL listings, motor out of airstream, hinge and cable, grease drain, clearances, and PCU requirements if used.
Roof plan: fan tag with hinge and restraint, duct height, drain routing, discharge direction, and clearance bubble.
Schedule: PCU enclosure rating, access, ventilation, and drain to grease interceptor.
Check: Fan Schedule and Equipment Detail
Fan schedule must show: fan type (grease-rated listed or standard), motor location (upblast or inline), drive type (direct or belt), and grease containment method.
Upblast fans must show the drip tray and drain routing on the fan detail or roof plan.
Electrical drawings must confirm the fan disconnect is within sight of the unit and on a dedicated branch circuit.
Review Risk:
Upblast fans without a drip tray and grease drain are the most common 506.5 inspection failure - show the containment detail on the roof plan.
Motors shown in the exhaust airstream will fail plan review - confirm motor location is noted outside the airstream in the schedule and on the fan detail.
Missing hinge, restraint cable, and flexible electrical conduit detail for upblast fans is a common incomplete-drawing comment.
Field Tip:
On the roof plan, add a "TYPE I FAN CHECK" line next to each fan: UL 705 listed, motor out of airstream, hinged with flex cable and restraint, duct 18" above roof, drain to grease reservoir, discharge not impinging, 18" clearance.
Masterbuild QA Lens
The 506 common duct manifold option (506.3.5) is frequently misapplied. Combining exhaust from multiple Type I hoods into a common duct requires: all hoods on the same system, fire suppression coverage of the entire common duct, and makeup air balanced to the combined exhaust. Confirm all three conditions are documented before using the common duct option.
Drawing / Submittal Check
For 506.5 exhaust equipment: the fan schedule must show the fan type (listed grease-rated or standard), the motor location (inline vs. upblast), the drive type (direct or belt), and the grease containment at the fan. Upblast fans must show the drip tray and drain. The electrical drawings must confirm the fan is on the required branch circuit with disconnect within sight.
Common Review Risk
Upblast fans without grease containment at the base are the most common 506.5 inspection failure. IMC 506 requires a drip tray or containment device below the upblast fan. Field installations that skip the drip tray because it was not on the drawing will fail inspection. Show the drip tray and drain connection on the fan detail.
When To Escalate
Escalate when the grease exhaust fan cannot be located on the roof - when the building configuration requires an inline fan inside the building or a fan in an interior mechanical room. Grease exhaust fans in interior locations require special fire-rated enclosures and access that must be pre-coordinated with the AHJ.
Rated Assembly Coordination
Exhaust equipment for commercial kitchen systems (506.5), including fans and plenums, may require rated enclosures or separation from combustible construction. Show the fan housing location, clearances, and any required rated separation on the equipment detail.
Load Assumption Check
Exhaust equipment for commercial kitchen systems (506.5) must be sized for the listed hood's maximum exhaust CFM. Confirm the fan curve intersects the system curve at design CFM with adequate static pressure margin for a dirty-filter or high-static condition.