Plain English:
502.11 motion picture projectors: If a projector has an exhaust collar, hard-connect it and size per manufacturer. Without a collar: electric arc >=200 cfm per lamp; xenon >=300 cfm per lamp and housing <=130 degrees F. Do not tie projection exhaust into other exhaust/return systems.
502.12 organic coating: Enclosed Class I organic coating processes: exhaust >=1 cfm/ft^2 of solid floor, pick up at floor level, discharge outdoors, and sweep the floor area with clean makeup air.
502.13-502.15 garages and pits: Public garages exhaust continuously or per IMC 404 + 403. Where Class I liquids or LP-gas can reach basements/pits, provide exhaust to prevent flammable vapor buildup.
502.14 motor vehicle operation: Areas with operating vehicles need IMC 403 ventilation + source-capture connected to tailpipes where engines run in place. Exceptions: EV-only, 1- and 2-family dwellings, or spaces where engines run only long enough to move vehicles in/out.
502.16 lighter-than-air fuel repair garages: CNG/LNG/hydrogen/other lighter-than-air fuels: provide mechanical exhaust with inlets low, outlets high, rate based on room volume, and automatic shutdown of fueling on exhaust failure. Hydrogen repair must also meet NFPA 2.
502.17 tires and dust: Rooms using rubber cement/flammable solvents follow NFPA 91. Buffing machines connect to dust collection to keep dust from accumulating.
502.18-502.19 special rooms: Specific rooms shall be exhausted per Chapter 4. Indoor firing ranges need ventilation that protects occupants and follows OSHA 29 CFR 1910.1025 where applicable.
502.20-502.20.1 manicure/pedicure: Provide local exhaust per Table 403.3.1.1 Note h. If no factory exhaust, add inlets within 12 in horizontally and vertically of where chemicals are applied, and run the exhaust whenever the space is occupied.
On Plans: Why it matters
These "special" occupancies come with specific rates, pickup locations, and interlocks.
Code Path: Where to show it
M-001: A "SPECIAL EXHAUST-IMC 502.11-502.20" note with key design bases (cfm/lamp, 1 cfm/ft^2, source capture, pit exhaust, mani/pedi pickup).
M-101 / M-601: Tag special exhaust rooms and match up with the exhaust schedule list EXHAUST TYPE, DESIGN BASIS, and CODE REF.
Check: Do
Ask early if the project includes cinemas, coating rooms, pits, gaseous-fuel repair, firing ranges, or salon stations and design to the process, not just the room name.
Call out design bases in the schedule
Review Risk: Don't
Tie special exhaust into general return or environmental exhaust.
Field Tip:
Standardize a "SPECIAL EXHAUST-IMC 502" so these occupancies are handled consistently on every job.
Masterbuild QA Lens
Makeup air for product-conveying exhaust must be shown as a dedicated system - not assumed from the building HVAC. Confirm the makeup air quantity matches the exhaust quantity, the supply source is clean (not from a hazardous area), and the controls sequence shows that makeup air activates with exhaust. Interlocks that fail open are not acceptable for hazardous applications.
Drawing / Submittal Check
For 502.11-502.20.1 (spray booths, semiconductor fabs, HPM storage): each specialty exhaust system must be called out on its own note on M-001 with the governing subsection. Cross-reference to NFPA 33 (spray finishing), NFPA 318 (semiconductor), or the applicable fire code section. Where a life-safety exhaust system requires standby power, show the standby power source and transfer time on the electrical drawings.
Common Review Risk
The most common 502.11-502.20.1
When To Escalate
Escalate for spray finishing operations in existing buildings where the fire separation and electrical classification cannot be achieved without significant structural modification, and for semiconductor fab exhaust systems that must comply with multiple standards simultaneously (IMC 502, NFPA 318, and the fire code). These are projects where pre-application meetings with all reviewing agencies are essential.
Special Condition-Battery Rooms
For battery rooms or charging areas, confirm the battery type, hazard basis, ventilation calculation, control sequence, alarm interface, exhaust path, and AHJ or fire-protection coordination are all traceable. The drawing set should not leave the safety logic implied.
Special Exhaust Coordination
For specialty exhaust, start with the contaminant and source. Then confirm capture method, duct material, routing, discharge, separation, controls, and whether another consultant or AHJ review is required.