/ Field knowledge · IMC 507.1 exceptions
“No hood required” is not a designer preference.
Commercial hoods are Type I or Type II. If any appliance under one hood requires Type I, the entire hood is Type I. “No hood required” is not a designer preference. IMC 507.1 exceptions only hold when the listing is on the drawings: UL 710B recirculating, listed integral downdraft (NFPA 96), smoker ovens with integral exhaust, UL 2162 wood-fuel ovens, UL 197 reduced-grease electric cooking, UL 921 dishwashers with self-contained condensing, or the heat/moisture-only path with space exhaust at 0.70 cfm/sf and 100 sf minimum per appliance.
Educational 2024 International Mechanical Code (IMC) 507.1 general exceptions from Daily Code Talk. Confirm the adopted edition. Distinct from 507.2 Type I construction and 505 vs 507. This is not a listing determination. Type I is always the “safe upgrade,” but it then triggers Type I installation rules.
- UL 710B factory-built recirculating systems (installed per IMC 304.1): several 507 hood rules do not apply. The space is still a kitchen and must be ventilated per Table 403.3.1.1. Floor-area calc: each appliance counts as at least 100 sf.
- No hood required (listed/approved cases): UL 710B recirculating; listed integral downdraft (NFPA 96); smoker ovens with integral exhaust listed/tested for the application; UL 2162 wood-fuel ovens (vented per manufacturer); UL 197 electric cooking for reduced grease emissions; UL 921 electric dishwashers with self-contained condensing.
- Heat/moisture-only appliances when HVAC / a separate removal system accounts for the load: space exhaust at 0.70 cfm/sf; each non-Type-II appliance at least 100 sf for floor-area calcs, plus that extra area exhausted at 0.70 cfm/sf.
On the set: M-001 “IMC 507 EXCEPTIONS” note with the exception number, listing standard, and model. Hood/appliance schedule: listing standard + model for every exception-driven decision. Heat/moisture path: 0.70 cfm/sf and 100 sf per appliance on the ventilation schedule. Coordinate with the authority having jurisdiction (AHJ) before issuing when relying on a 507.1 exception. Undocumented exceptions are the most common 507.1 comment.
“Recirc hood” with no UL 710B
Or a downdraft with no NFPA 96 listing. Or skipping hood exhaust and also skipping 0.70 cfm/sf. That is still a Type I or Type II hood — plus a first-cycle comment.
Source: Daily Code Talk — IMC 507.1 exceptions · tool: Exception screen · Type I: 507.2 · 505: domestic vs commercial.
What to send
The appliance lineup, any “no hood” or recirculating claim, and the listing (UL 710B / 197 / 921 / 2162 / NFPA 96) if one exists.
If the set says “no hood required” with no listing
Send the lineup. Masterbuild will say whether 507.1 still has an undocumented exception — or one steam table is still dragging the whole hood to Type I.
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. UL 710B / 197 / 921 / 2162, NFPA 96 downdraft, 0.70 cfm/sf, and 100 sf per appliance are 2024 IMC 507.1 education from Daily Code Talk — not a listing determination. This page is not legal advice.