What each damper does, where the building code calls for it, and the ratings to specify. Use the damper tool to find out which one your penetration needs.
Fire damper
Test standard: UL 555
A fire damper closes automatically when its heat-responsive device, usually a fusible link, reaches its operating temperature. It keeps fire from passing through ducts and air transfer openings in fire-resistance-rated walls and floors.
Where it is used: Fire walls, fire barriers, shaft enclosures, fire partitions, rated exterior walls with protected openings, and duct penetrations of rated floors.
Rating: At least 1-1/2 hours in assemblies rated less than 3 hours, and 3 hours in assemblies rated 3 hours or more.
IBC 717.3.1, Table 717.3.2.1, 717.3.3.1
Smoke damper
Test standard: UL 555S
A smoke damper closes when smoke detection signals it, through an actuator, to stop smoke from moving through the duct system.
Where it is used: Smoke barriers, rated corridors that need smoke and draft control doors, horizontal exits, shaft enclosures, and air transfer openings in smoke partitions.
Rating: Leakage Class I or II, and an elevated temperature rating of at least 250°F.
IBC 717.3.1, 717.3.2.2, 717.3.3.2
Combination fire/smoke damper
Test standard: UL 555 and UL 555S
One assembly that meets both the fire damper and the smoke damper standards. Where an opening needs both, the code allows a combination damper or a separate fire damper and smoke damper.
Where it is used: Typical at shaft enclosure penetrations and at fire walls or fire barriers that serve as horizontal exits.
Rating: The fire damper rating from Table 717.3.2.1 plus the smoke damper leakage and temperature ratings.
IBC 717.5, 717.3.2.3
Corridor damper
Test standard: UL 555 and UL 555S
A damper tested for both fire and smoke and for closing against airflow, installed where a duct passes through a corridor ceiling that is built like the corridor walls.
Where it is used: Rated corridor ceilings constructed as permitted by IBC 708.4 Exception 3.
Rating: At least 1 hour fire rating, leakage Class I or II, and closure at 150 feet per minute during the UL 555 fire test.
IBC 717.3.1 item 5, 717.3.2.4, 717.5.4.1
Ceiling radiation damper
Test standard: UL 555C
A ceiling radiation damper protects an opening in the ceiling membrane of a rated floor/ceiling or roof/ceiling assembly, usually above a diffuser or grille, from radiant heat that would otherwise reach the structure above.
Where it is used: Duct and diffuser openings in the ceiling of rated floor/ceiling and roof/ceiling assemblies, and corridor ceilings that are the membrane of a rated floor above.
Rating: Listed to UL 555C or tested as part of the rated assembly. HVAC systems whose fans run during a fire need dampers labeled for dynamic systems.
IBC 717.3.1 item 4, 717.6.2, 717.6.2.1
Installation basics that apply to every damper
Install to the listing. Dampers must be installed as the manufacturer’s instructions and the listing require. IBC 717.2
Access. Provide access large enough to inspect and maintain the damper. Dampers with fusible links or internal operators need an access door at least 12 inches square or a removable duct section. IBC 717.4.1
Labels. Mark each access point with letters at least 1/2 inch high reading FIRE DAMPER, SMOKE DAMPER or FIRE/SMOKE DAMPER. IBC 717.4.2
Static versus dynamic. Dampers listed for static systems may be used only in HVAC systems that shut down automatically in a fire. IBC 717.2.3 (2021 and 2024)
No flexible duct through rated assemblies. Flexible ducts and connectors may not pass through any fire-resistance-rated assembly. IBC 717.7
No controls through dampers (2024). Mechanical, electrical and plumbing controls may not be installed through dampers unless the manufacturer and listing allow it. IBC 717.2.4.1
Inspection and testing. NFPA 80 (fire dampers) and NFPA 105 (smoke dampers) cover periodic inspection and testing, including remote inspection where access is restricted. IBC 717.4.1.2