Damper Guide

Damper types

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

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.

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 555 and UL 555S
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.
Closes on
Actuated as both a fire damper (heat) and a smoke damper (smoke detection).

IBC 717.3.1 item 5, 717.3.2.4, 717.3.3.5

Where the IBC requires a corridor damper

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

What to specify

All three editions

  • Listed to UL 555 and UL 555S
  • Fire rating: at least 1 hour
  • Leakage rating: Class I or Class II
  • Must close against 150 feet per minute airflow during the UL 555 fire test
  • Actuated as both a fire damper (heat) and a smoke damper (smoke detection)

IBC 717.3.1 item 5, IBC 717.3.2.4, IBC 717.3.3.5

Corridor damper vs combination fire/smoke damper

Both meet UL 555 and UL 555S. A corridor damper has a 1-hour minimum fire rating instead of the fire damper table, and it must also pass the code’s 150 feet per minute closure test during the UL 555 fire exposure (IBC 717.3.1 item 5). It is required only in corridor ceilings built like the corridor walls. More about the combination fire/smoke 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

Where is a corridor damper required?

Corridor damper: requiredAll three editions

Corridor damper: required. The corridor ceiling is built like the corridor walls (IBC 708.4 Exception 3), so a corridor damper is required where the duct passes through it. Corridor dampers are tested for both fire and smoke. IBC 717.5.4.1 item 1, IBC 717.3.1 item 5

Full result in the tool: Corridor damper required

What if the corridor walls stop at the ceiling of a rated floor?

Then the ceiling is the membrane of the rated floor, and a ceiling radiation damper is required instead.

Ceiling radiation damper: requiredAll three editions

Ceiling radiation damper: required. The corridor walls stop at the ceiling of a rated floor or roof assembly (IBC 708.4 Exception 2), so a ceiling radiation damper is required where the duct passes through that ceiling. IBC 717.5.4.1 item 2

Also: For a corridor ceiling under a rated floor: IBC 717.5.4.1 item 2 lists no exception. If the floor/ceiling or roof/ceiling assembly listing shows no ceiling radiation damper is needed, raise it with the building official. IBC 717.5.4.1 item 2

Full result in the tool: Smoke damper and ceiling radiation damper required

Illustration