/ Field knowledge · IMC 508
Makeup air is part of the hood, not a GC leftover.
A Type I hood that is sized correctly still fails if the kitchen goes negative. IMC 508 is replacement air — not dining outdoor air, and not an undercut door.
Educational reading of 2024 IMC 508 as model code. Confirm the adopted FBC Mechanical edition. This is not a makeup-air design for your hood. Packet: 508 PDF · ES.
What has to be on the M-sheets
- Quantity. Makeup air coordinated with hood exhaust. The equality check is a first-pass, not a balance report.
- Where it enters. Dumping air onto the cooking plume kills capture. Location relative to the hood, the line, doors, and dining matters.
- When it runs. Makeup air has to operate with the hood exhaust — interlock, not a note.
- What it is not. Table 403 dining OA, transfer from a corridor, and undercut doors are not 508 makeup air for a Type I hood.
Late equipment add-on
If architecture, shafts, and exterior openings are already locked, makeup air becomes a redesign. Ask early: where does the replacement air come from, and will it help the hood?
Related: DCT 508 · kitchen hub · termination · hood + interceptor.
What to send
Equipment schedule, hood exhaust cfm if known, existing HVAC, roof/wall openings, and whether this is a new hood or a replacement in a tight envelope.
If the hood is drawn and the replacement air is not
Send the equipment schedule and the architectural kitchen. MasterBuild will say whether 508 is even on the path.
Send Project Background+1 (786) 398-6940 · osmany.portal@masterbuildconsulting.com
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