/ Field knowledge · IMC 202
The wrong word on the schedule is a first-cycle comment.
IMC 202: the wrong word on the schedule is a first-cycle comment. “Ceiling cavity” for a return path looks like an exemption from 602.2. “Fire damper” for smoke control is the wrong device.
Educational 2024 IMC Chapter 2. Confirm adopted edition. This is not a glossary of every defined term — see IMC glossary. Five high-impact terms from Daily Code Talk:
- Appliance vs equipment. Appliance = manufactured device that uses energy and is directly regulated (listings and manufacturer instructions bind it). Equipment = system components (ducts, vents, piping, controls). Using “equipment” for a listed heating/cooling appliance changes which installation section applies.
- AHU = the blower/fan box. Air-conditioning system = AHU + coils/filters + ducts. Air distribution system = ducts/plenums/equipment that move air. Label precisely or testing and listing follow the wrong object.
- Plenum = an enclosed building portion intentionally used as part of the air distribution system. Triggers material limits, wiring/insulation ratings, and fire/smoke coordination. Use “plenum,” not “ceiling cavity.” See plenums.
- Fire damper stops flame. Smoke damper stops smoke. Combination does both. See 607.
- Ceiling radiation damper (CRD) is a listed device at penetrations of rated floor/ceiling or roof/ceiling assemblies to limit radiative heat transfer at air openings. CRD is not a fire damper.
Cover-sheet language from Daily Code Talk: definitions per IMC Chapter 2; if undefined, see IBC/IFC/IFGC/IPC; if still undefined, use commonly accepted meaning per IMC 201.4.
Trade name on the damper schedule
Use the exact IMC/IBC term and the UL listing number. Definition disputes — whether a space is a plenum, whether a product is listed — often cannot be closed with a drawing revision alone. Get the AHJ interpretation in writing.
Source: DCT 202 redlines · glossary: IMC glossary · comments: typical comments.
What to send
The equipment/damper schedule and the comment that used a different word than the drawing.
If the comment is about the word on the schedule
Send the schedule line. MasterBuild will say whether 202 even has that term — or the set used “ceiling cavity” for a plenum.
Send Project Background+1 (786) 398-6940 · osmany.portal@masterbuildconsulting.com
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