IBC 717.5.6
Fire dampers in exterior walls (IBC 717.5.6)
An exterior wall needs fire dampers only where it is fire-resistance rated and its openings must be protected because of how close it is to a lot line or another building.
What counts as an exterior wall: An outside wall that is fire-resistance rated because it is close to a lot line or another building.
Rules last reviewed October 12, 2026. How the rules are checked
Check your case in the tool (2024 IBC)Start the tool with the 2021 IBC · Start the tool with the 2018 IBC
When each damper is required
Every result the tool can give for a duct carrying heating, cooling or ventilation air, or an air transfer opening, through this assembly. Labels show where a result applies only to ducts, only to air transfer openings, or only in some editions.
Fire damper
- Required
The exterior wall is rated and must have protected openings, so ducts and air transfer openings need a listed fire damper.
IBC 717.5.6, IBC 705.10 (2018 and 2021), IBC 705.11 (2024)
- Not required
The exterior wall is not required to have protected openings.
IBC 717.5.6
Also required
- Foundation vents installed as the code allows are permitted without dampers. IBC 705.10 Exception (2018 and 2021), IBC 705.11 Exception (2024)
- Flexible ducts and flexible air connectors may not pass through any fire-resistance-rated assembly, and flexible air connectors may not go through any wall, floor or ceiling at all. (ducts only) IBC 717.7
- If the wall is fire-resistance rated, the penetration must still be firestopped so the wall keeps its rating. IBC 717.1.2, IBC 714.3 to 714.4.3
Common situations by edition
| Situation | 2024 IBC | 2021 IBC | 2018 IBC |
|---|---|---|---|
| Duct through a 1-hour exterior wall that must have protected openings | Fire damper required | Fire damper required | Fire damper required |
| Duct through an exterior wall where unprotected openings are allowed | No damper required | No damper required | No damper required |
| Louver or air transfer opening in a 1-hour exterior wall that must have protected openings | Fire damper required | Fire damper required | Fire damper required |
Select a result to open it in the tool with every answer filled in, including the conditions not listed here.
Exceptions and conditions the tool checks
These are the questions the tool asks, in order, with the explanation it gives. Section numbers are shown for each edition where they differ.
Is the exterior wall fire-resistance rated and required to have protected openings?
2018 and 2021 IBC
Table 705.8 sets how much opening area is allowed, and whether it must be protected, based on the fire separation distance. Within 3 feet of the lot line no openings are allowed at all. Farther away, many sprinklered buildings may have a limited percentage of unprotected openings.
IBC Table 705.8, IBC 705.10, IBC 717.5.6
2024 IBC only
Table 705.9 sets how much opening area is allowed, and whether it must be protected, based on the fire separation distance. Within 3 feet of the lot line no openings are allowed at all. Farther away, many sprinklered buildings may have a limited percentage of unprotected openings.
IBC Table 705.9, IBC 705.11, IBC 717.5.6
What is the required fire-resistance rating of the assembly?
Use the rating the code requires for this wall or floor, shown on the life safety plans.
Code changes that affect this assembly
- Exterior walls: The damper rule did not change. In 2024 the section it points to was renumbered from 705.10 to 705.11.
Questions
When does a duct through an exterior wall need a fire damper?
When the wall is rated and must have protected openings.
Fire damper: requiredAll three editions
Fire damper: required. The exterior wall is rated and must have protected openings, so ducts and air transfer openings need a listed fire damper. IBC 717.5.6, IBC 705.11 (2024), IBC 705.10 (2018 and 2021)
Also: Foundation vents installed as the code allows are permitted without dampers. IBC 705.11 Exception (2024), IBC 705.10 Exception (2018 and 2021)
Full result in the tool: Fire damper required
What if the wall may have unprotected openings?
Fire damper: not requiredAll three editions
Fire damper: not required. The exterior wall is not required to have protected openings. IBC 717.5.6
Also: If the wall is fire-resistance rated, the penetration must still be firestopped so the wall keeps its rating. IBC 717.1.2, IBC 714.3 to 714.4.3
Full result in the tool: No damper required
Why does the 2024 result cite a different section?
The exterior wall opening section was renumbered from 705.10 to 705.11 in 2024. The damper rule itself did not change.