Daily Code Talk #66: IMC 507 Part 3 (507.2–507.2.7 Type I Hoods Basics)

🧠 Plain-English Highlights• 507.2 where Type I is required- Type I hoods are required where appliances produce grease or smoke. That generally means medium-, heavy-, and extra-heavy-duty cooking.• 507.2.1 label check- Type I hoods must be labeled with the minimum exhaust flow rate (cfm per linear foot) needed for capture and containment based on duty classification.• 507.2.2 extra-heavy-duty restriction- Type I hoods serving extra-heavy-duty appliances cannot cover heavy-, medium-, or light-duty appliances. Also, they must discharge to an exhaust system independent of other exhaust systems.• 507.2.3 materials- Minimum construction: Steel: 18 ga min (0.0466 in) OR Stainless: 20 MSG min (0.0335 in)• 507.2.4 supports- Noncombustible supports required. Design supports for hood load plus: unsupported grease duct load, effluent loading, and potential personnel loads.• 507.2.5 joints and penetrations- Exterior joints/seams/penetrations: continuous external liquid-tight weld/braze to the lowest outermost perimeter.- Interior seams/appendages: not required to be welded, but must be sealed grease-tight.Exceptions allow listed sealing devices and internal welds if smooth/cleanable.• 507.2.6 clearances- Default: 18 in clearance to combustibles.Exceptions include noncombustible wallboard protection approach and UL 710 listed hoods with reduced clearances (follow listing).• 507.2.7 hood portions penetrating ceilings/walls/furred spaces- Must comply with 506.3.11 enclosure requirements. Field-applied grease duct wrap systems (506.3.11.2) cannot be used to satisfy this specific requirement.🏗️ Why it mattersTypical redlines: “Type I” labeled with no hood listing/label value shown, missing liquid-tight construction notes, 18 in clearance conflicts, and ceiling penetrations drawn with no enclosure strategy.🗺️ Where to show it• M-001: Type I hood note (materials, liquid-tight exterior, clearance basis, UL 710 listing if applicable, and “penetrations comply with 506.3.11”).• M-101/Kitchen elevations: hood type, duty classification, and clearance callouts.• Details: hood-to-wall protection detail where using the gypsum/cement board exception.✅ Do• Put the hood label info on the schedule (duty + min cfm/lf).• Coordinate clearances early so the architect isn’t boxed in later.⛔ Don’t• Don’t mix appliance duty levels under an extra-heavy-duty hood.• Don’t show a ceiling/furred-space penetration without the enclosure approach.🔧 Field tipIn your hood schedule, add a “TYPE I CHECK” line: DUTY CLASS + HOOD LABEL (CFM/LF) + MATERIAL (18 GA / SS 20 MSG) + LIQUID-TIGHT EXTERIOR + 18" CLR/UL 710 CLR + PENETRATION (Y/N → 506.3.11).Comment “IMC507-P3” if you want a paste-ready Type I hood schedule template.