/ Field knowledge · IMC 507.1.1–507.1.7
A Type I fan that does not auto-start is not coordinated.
The hood is a life-safety system, not a “kitchen exhaust note.” IMC 507.1.1: Type I fans auto-start with appliance operation, or the appliances cannot run unless exhaust is on. Sensor-based start: the fan activates within 15 minutes of the first appliance being turned on. Interlocks cannot extinguish standing pilots or rely on the fire-suppression system. After install and before final approval: verify exhaust airflow, makeup air per 508, and capture with smoke or steam under real operating conditions — appliances hot, makeup on, space HVAC on.
Educational 2024 International Mechanical Code (IMC) 507.1.1–507.1.7 from Daily Code Talk. Confirm the adopted edition. Distinct from 507.1 exceptions and 507.1.6 geometry. This is not a controls design.
- 507.1.1: hoods operate during cooking. Exhaust rate follows the hood listing or the code tables (Type I: 507.2.10, Type II: 507.3.4). Type I: auto-start with appliances or interlock so appliances cannot run without exhaust.
- Sensor start: within 15 minutes of the first appliance on. Interlocks cannot kill standing pilots or depend on suppression.
- 507.1.1.1 multiple hoods on one exhaust with sensors: each hood has its own sensor, accessible from the hood outlet or a cleanout.
- 507.1.2: “residential” appliances used for commercial purposes get Type I or II hoods per 507.2 / 507.3 — not IMC 505. See 505 vs 507.
- 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: designed for thorough cleaning. Outlets optimize capture; each outlet serves max 12 ft of hood.
- 507.1.7 / 507.1.7.1: performance test after install, before final. Capture and containment verified visually with smoke/steam under real conditions.
No interlock narrative, no capture-test note
Or a residential range used commercially still sitting on 505. Or a water heater in the same room as a Type I hood. Those fail plan review and the final inspection.
Source: Daily Code Talk — IMC 507.1 operation · exceptions: 507.1 listings · makeup: 508 · geometry: 507.1.6.
What to send
How the Type I fan starts (auto, interlock, or sensor), whether any residential appliance is used commercially, and whether a capture-and-containment test is specified.
If the Type I fan has no auto-start path
Send the sequence. Masterbuild will say whether 507.1.1 still has no interlock — or 507.1.7 still has no capture-test note.
Send Project Background+1 (786) 398-6940 · osmany.portal@masterbuildconsulting.com
Masterbuild provides engineering services under a written scope. Nothing on this page is project-specific engineering advice, a code interpretation for your project, or a representation about permit approval. Confirm the adopted edition. 15-minute sensor start, 12 ft per outlet, 507 not 505 for commercial use of residential appliances, and the smoke/steam capture test are 2024 IMC 507.1 education from Daily Code Talk — not a controls design. This page is not legal advice.