Damper Guide

Damper types

Smoke dampers: where the IBC requires them and what to specify

A smoke damper closes when smoke detection signals it, through an actuator, to stop smoke from moving through the duct system.

Rules last reviewed October 12, 2026. How the rules are checked

Check which damper your penetration needs (2024 IBC)Start the tool with the 2021 IBC · Start the tool with the 2018 IBC

Standard, rating and actuation

Test standard
UL 555S
Rating
Leakage Class I or II, and an elevated temperature rating of at least 250°F.
Closes on
Listed smoke detection. Depending on where the damper is, that can be a duct detector (or sampling tubes) within 5 feet of the damper with no air outlets or inlets between them, spot detectors beside smoke barrier doors or within 5 feet of a transfer opening, corridor smoke detection, or a detection system covering every area the duct serves. The spot detectors at smoke barrier doors and at wall air transfer openings must be listed for releasing service when they connect directly to the damper, and where a duct detector needs airflow to work, the damper closes when the fan shuts down (except in mechanical smoke control systems).

IBC 717.3.1, 717.3.2.2, 717.3.3.2

Where the IBC requires a smoke damper

Where the IBC requires a smoke damper, unless an exception applies (each page lists the exceptions):

What to specify

All three editions

  • Listed to UL 555S
  • Leakage rating: Class I or Class II
  • Elevated temperature rating: at least 250°F
  • Closes on activation of listed smoke detection as described in IBC 717.3.3.2

IBC 717.3.1, IBC 717.3.2.2, IBC 717.3.3.2

Smoke damper vs fire damper

A smoke damper is rated for leakage and temperature, not for fire resistance, and it closes on a smoke signal rather than on heat. It cannot stand in for a required fire damper. Where both are required, use a combination fire/smoke damper or one of each. More about the fire damper.

Installation basics

  • Access. Fire and smoke dampers need access large enough to inspect and maintain the damper. Since 2021, dampers with fusible links or internal operators need an access door at least 12 inches square or a removable duct section. IBC 717.4 (2018), 717.4.1 (2021 and 2024)
  • 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 (717.4 in 2018)
  • Restricted access (2021 and 2024). Where access for periodic inspection and testing is restricted, use a single- or multi-blade damper that meets the remote inspection requirements of NFPA 80 (fire dampers) or NFPA 105 (smoke dampers). IBC 717.4.1.2

Rules for every damper type (installing to the listing, no flexible ducts through rated assemblies, no controls through dampers in 2024) are on the damper types page.

Questions

Does a smoke damper have an hourly fire rating?

No. It has a leakage class (I or II) and an elevated temperature rating of at least 250°F. Where a fire damper is also required, use a combination fire/smoke damper or add a fire damper.

Do ducts through smoke partitions need smoke dampers?

No, only air transfer openings do.

Smoke damper: not requiredAll three editions

Smoke damper: not required. Smoke partitions need smoke dampers only at air transfer openings, not at ducts. IBC 717.5.7, IBC 710.8

Also: Fill the space around the duct with an approved material to limit the passage of smoke. IBC 710.8

Full result in the tool: No damper required

Does a fire barrier need smoke dampers?

Only where it serves as a horizontal exit.

Smoke damper: requiredAll three editions

Smoke damper: required. The fire barrier serves as a horizontal exit, so a listed smoke damper is required. IBC 717.5.2.1

Full result in the tool: Combination fire/smoke damper required

Illustration