/ Field knowledge · IMC 607.5.4
A CRD is not a smoke damper.
Corridor and smoke-barrier penetrations are a smoke-control question, not just a rating question. A listed smoke damper (SD) at the wall, a corridor damper (CD) at a corridor ceiling membrane, and a ceiling radiation damper (CRD) at a rated floor/ceiling or roof/ceiling membrane are three products. They are not interchangeable. A CRD is not a fire damper and not a smoke damper.
Educational 2024 International Mechanical Code (IMC) 607.5.4 from Daily Code Talk. Confirm the adopted edition and the IBC assembly. Distinct from fire partitions (607.5.3) and shafts (607.5.5). This is not a damper schedule.
- Listed SD where a duct or transfer opening penetrates a smoke-barrier wall, and where it penetrates a corridor enclosure required by the IBC to have smoke and draft control doors.
- CD where corridor ceilings are constructed as required for corridor walls and are penetrated. A CD is specific to that ceiling membrane — not a substitute for an SD at the wall.
- CRD where the ceiling membrane of a rated floor/ceiling or roof/ceiling assembly is penetrated under the applicable IBC condition. Run CRD as a separate pass from the wall damper.
- Exceptions exist (approved smoke-control system; steel ducts limited to one smoke compartment; minimum 0.019-inch steel duct with no openings serving the corridor; a Group I-2, Condition 2 path). Name the exception. Do not omit an SD without proving it. 607.5.4.1: SD closes as required by 607.3.3.2 — detector, signal, and closure coordinated with fire alarm.
On the set: wall type first (corridor enclosure vs smoke barrier vs rated ceiling membrane), then SD / CD / CRD, listing, actuator, access, and the exception basis on M-001. Fire-alarm sequence on M-603.
Duct through a smoke barrier, no SD, no exception
Or a CD treated as a wall question only. Or a CRD missing at the rated ceiling membrane. Three separate checklist items. If the plans do not identify the wall type, the exception cannot be verified.
Source: Daily Code Talk — IMC 607.5.4 · partitions: 607.5.3 · shafts: 607.5.5 · floors: 607.6 · 607: name the assembly.
What to send
Life-safety plan with corridors and smoke barriers marked, the duct plan at those walls, and whether any rated ceiling membrane is penetrated.
If the typical only says “F/S at rated walls”
Send the rated plan. Masterbuild will say whether 607.5.4 still has no SD at the smoke barrier — or a CRD still missing at the ceiling membrane.
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. SD, CD, CRD, and the 0.019-inch steel exception are 2024 IMC 607.5.4 education from Daily Code Talk — not a damper schedule. This page is not legal advice.