Guide

IBC Section 717: where dampers are required

Section 717 of the International Building Code decides when a duct or air transfer opening needs a fire damper, smoke damper, combination fire/smoke damper, corridor damper or ceiling radiation damper. It works assembly by assembly: what the duct passes through decides which rule applies, and each rule has its own exceptions.

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

Check a penetration in the tool (2024 IBC)Start the tool with the 2021 IBC · Start the tool with the 2018 IBC

How Section 717 works

1. Five damper types. Section 717.3 sets the test standard, rating and actuation for each: fire dampers, smoke dampers, combination fire/smoke dampers, corridor dampers and ceiling radiation dampers.
2. Where dampers are required depends on the assembly. Section 717.5 covers walls (fire walls, fire barriers, shafts, fire partitions and corridors, smoke barriers, exterior walls and smoke partitions). Section 717.6 covers floors and the ceilings of rated floor/ceiling and roof/ceiling assemblies. A wall that is rated only for structural reasons is not on the list.
3. Each rule has its own exceptions. Typical ones are penetrations tested as part of the rated assembly, smoke control systems, fully ducted steel HVAC systems in sprinklered buildings, and steel exhaust subducts in shafts. See the 1-hour fire barrier exception and the shaft damper exceptions.
4. Fire and smoke are separate questions. An exception that removes the fire damper does not remove a smoke damper that another rule still requires. Where both are required, use a combination fire/smoke damper or a separate fire damper and smoke damper.
5. Some exhaust ducts may not have dampers at all. The International Mechanical Code prohibits them in clothes dryer exhaust, commercial kitchen grease ducts and hazardous exhaust, and requires other protection. See dryer, grease and hazardous exhaust ducts.
6. Installation rules. Every damper is installed to its listing, and flexible ducts may not pass through rated assemblies (Sections 717.2 and 717.7). Fire and smoke dampers also need access for inspection and labels at the access points (Section 717.4), and the static or dynamic listing matters for fire dampers and ceiling radiation dampers. See the installation basics.
7. The editions differ. Several damper rules changed in the 2021 IBC and again in the 2024 IBC. Compare all three editions side by side.

Walls (IBC 717.5)

The dampers the tool can require for a duct or air transfer opening through each wall, depending on the answers.

Floors, ceilings and roofs (IBC 717.6)

Ducts through floors usually need a shaft. The floor rules say when a damper at the floor line or in the ceiling may be used instead.

Exceptions and prohibitions in detail

• The 1-hour fire barrier exception
• Shaft damper exceptions
• Dryer, grease and hazardous exhaust ducts

Damper types

• Fire damper: test standard, ratings and where it is required
• Smoke damper: test standard, ratings and where it is required
• Combination fire/smoke damper: test standard, ratings and where it is required
• Corridor damper: test standard, ratings and where it is required
• Ceiling radiation damper: test standard, ratings and where it is required