IMC 507 starts with one idea: the hood is a life safety system, not a "kitchen exhaust note." If it does not match the appliances, capture the effluent, and operate correctly, everything downstream breaks.
Plain English: Plain-English Highlights
507.1 hood type rules
Commercial hoods must be Type I or Type II and designed to capture and confine cooking vapors and residues.
If ANY appliance under a single hood requires Type I, the whole hood must be Type I.
If Type II is required, you can install Type I or Type II.
507.1.1 operation and interlocks
Hoods must operate during cooking.
Exhaust rate must follow the hood listing OR the code sizing tables (Type I: 507.2.10, Type II: 507.3.4).
Type I fan must auto-start with appliance operation OR appliances must be interlocked so they cannot run unless exhaust is on.
Sensor-based start: fan must activate within 15 minutes of the first appliance being turned on.
Interlocks cannot extinguish standing pilots OR rely on the fire suppression system.
Multiple hoods on one exhaust (507.1.1.1)
If sensors are used and multiple hoods share one exhaust system, each hood needs its own sensor and be accessible from the hood outlet or a cleanout.
Domestic appliances used commercially (507.1.2): "Residential" appliances used for commercial purposes, provide Type I or II hoods per 507.2/507.3 (not IMC 505).
Fuel-burning conflicts (507.1.3): Draft-hood/atmospheric burner appliances are not allowed in the same space as a Type I or II hood unless in a sealed, self-closing enclosure with compliant combustion air.
507.1.4 + 507.1.5 practical design notes
Hood must be designed for thorough cleaning.
Hood outlets must optimize capture and each outlet serves max 12 ft of hood.
507.1.7 performance test + 507.1.7.1 capture test
Required after install and before final approval: verify exhaust airflow, makeup air per Section 508, and proper operation.
Capture and containment is verified visually with smoke/steam under real operating conditions (appliances hot, MUA on, space HVAC on).
On Plans: Why it matters
Common redlines: mixed-duty appliances under one hood without correct Type I call, missing interlock narrative, sensors shown without access, and no plan for performance testing.
Code Path: Where to show it
M-001: IMC 507.1 note with hood type logic, exhaust basis (listed or code), Type I interlock language, and testing requirements (507.1.7 and 507.1.7.1).
M-601 schedule: hood type, appliances served, exhaust basis, controls/interlock, design CFM, MUA CFM (508).
Field Tip: Field tip
Add an "IMC 507.1 CHECK" on the hood schedule: TYPE (I/II) + INTERLOCK (Y/N) + EXH BASIS (LISTED/CODE) + SENSOR PER HOOD (Y/N) + MUA (508) + PERF TEST (507.1.7).
Comment "IMC507-P1" if you want a paste-ready M-001 note + hood schedule header.
Masterbuild QA Lens
Exhaust systems need a source-to-discharge story. Identify what is being captured, how it is captured, how it is routed, where it terminates, and what interlocks or separations protect the building.
Drawing / Submittal Check
Verify source classification, hood or pickup point, duct material, route, cleanouts or access, fan selection, discharge location, make-up air, controls, and required coordination with fire protection or alarms.
Common Review Risk
The expensive miss is treating all exhaust the same. Grease, dryer, dust, hazardous, smoke control, battery, and specialty exhaust systems carry different proof requirements.
When To Escalate
Escalate when exhaust involves grease, hazardous materials, combustible dust, battery charging, smoke control, rated shafts, energy recovery, or any discharge that can re-enter the building.
Kitchen Exhaust Coordination
For kitchen exhaust, tie the hood schedule, appliance lineup, grease duct route, cleanouts, fan discharge, fire suppression interface, and make-up air strategy into one reviewable story.
Duct System Coordination
For duct and plenum items, check material limits, insulation continuity, vapor control, access, listed products, and whether the surrounding space changes the requirement.