IMC 607.5 starts the 'where required' portion of duct and transfer opening protection. This is where the reviewer matches the assembly type to the correct damper, exception, and listing. A duct crossing a rated wall may need a fire damper, a smoke damper, a combination FD/SD, or both - the answer depends on which assembly type is being crossed.
Plain English: Plain-English Highlights
607.5 Where Required
Fire dampers (FD), smoke dampers (SD), combination fire/smoke dampers (FD/SD), ceiling radiation dampers (CRD), and corridor dampers are required at the locations listed in 607.5.1 through 607.5.7.
Where an assembly requires both fire and smoke protection, provide a combination FD/SD or both a FD and SD. A fire damper alone does not provide smoke control at a horizontal exit.
607.5.1 Fire Walls
Ducts and air transfer openings permitted through fire walls by IBC 706.11 must be protected with listed FDs installed per their listing. Fire walls are the most restrictive vertical assembly - penetrations are limited and require a permitted opening under IBC 706.11.
607.5.1.1 Horizontal Exits
Where a fire wall serves as a horizontal exit, each duct or air transfer opening also needs a listed SD. The FD alone is not sufficient - the opening must also resist smoke.
607.5.2 Fire Barriers
Ducts and air transfer openings through fire barriers generally require listed FD.
Ducts and air transfer openings cannot penetrate interior exit stairways, ramps, or exit passageways except where permitted by IBC 1023.5 and 1024.6.
607.5.2 Exceptions
FD are not required at certain fire barrier penetrations where the penetration is tested as part of the rated assembly, where smoke control would be impaired, or where the fully ducted HVAC exception is met.
The fully ducted exception is not a blanket pass. It is limited to 1-hour-or-less fire barriers, non-Group H areas, sprinklered buildings, and continuous minimum 26 gage sheet steel duct from equipment to terminals. All four conditions must be met simultaneously.
607.5.2.1 Horizontal Exits
Where a fire barrier serves as a horizontal exit, each duct or air transfer opening also needs a listed SD - same requirement as fire walls.
On Plans: Why it matters
Fire walls, fire barriers, and horizontal exits are not interchangeable. A duct crossing a rated wall may need a FD, SD, both, or an exception. If the plans do not identify the wall type and exception basis, the damper callout is incomplete. Applying a fire barrier exception to a fire wall is a code error - not a conservative choice.
Code Path: Where to show it - M-001: IMC 607.5 damper notes and exception criteria - M-101: duct and transfer openings at fire walls, fire barriers, and horizontal exits - M-501: damper, sleeve, access, and penetration details with UL design number - M-603: damper actuation and smoke control coordination - A / LS sheets: rated assembly labels - the mechanical plan must match the architectural life-safety plan
Check: Do - Identify the rated assembly type before selecting the damper - Show whether FD, SD, or FD/SD protection is required at each penetration - Coordinate horizontal exits carefully - they require an SD at both fire walls and fire barriers - For the fully ducted exception, document all four conditions on M-001
Review Risk: Don't - Don't treat fire walls and fire barriers the same - they have different structural roles and different damper rules - Don't omit SD at horizontal exits where required - Don't apply the fully ducted exception without confirming duct gauge, occupancy, sprinkler status, and barrier rating
Field Tip: Field tip Before applying any exception, ask: what wall is this, what is its rating, does it serve as a horizontal exit, and is the duct truly continuous and fully ducted where that exception is used? If the drawings don't answer all four questions, the exception basis is not established.
Masterbuild QA Lens
The most common 607.5 error is applying a fire barrier exception to a fire wall penetration. Confirm the assembly type from the architectural life-safety plan before selecting the damper. If the architectural drawings do not clearly label the assembly type, request written coordination confirmation before submittal.
Drawing / Submittal Check
For every duct and air transfer opening through a rated vertical assembly: (1) label the assembly type on the mechanical plan; (2) show the required damper type with its listing basis; (3) for exception conditions, note the specific exception and all conditions met on M-001; (4) for horizontal exits, confirm FD and SD are both shown. Cross-check the damper schedule against the architectural life-safety plan - assembly labels must agree.
Common Review Risk
Two patterns generate most 607.5 plan review comments: (1) damper type selected without identifying the assembly type; (2) fully ducted exception applied without showing duct gauge, occupancy, sprinkler coverage, and barrier rating on the drawings. Label the assembly and show the exception basis explicitly.
When To Escalate
Escalate when the rated assembly type cannot be confirmed from the architectural drawings, when a duct must cross a horizontal exit that was not anticipated in early design, or when the smoke control basis conflicts with the required damper closure mode.
Rated Assembly Coordination
Fire walls must be able to stand independently after fire destroys either adjacent section. Mechanical penetrations through fire walls are limited and require PE-level coordination with the structural and architectural team to confirm that the opening is permitted under IBC 706.11.