Code changes
2024 IBC damper changes
Damper requirements in the 2024 International Building Code compared with the 2021 edition: 1 changed, 1 new, 1 renumbered, out of the 12 topics the edition comparison tracks. Each entry gives the requirement before and after, in plain language with the section numbers of both editions.
Rules last reviewed October 12, 2026. How the rules are checked
Ducts through floors in Groups I-2 and I-3
Changed
In 2024 the Group I-2 and I-3 limit moved from the main rule to the three-floor exception.
2021 IBC 717.6.1
Outside Groups I-2 and I-3, a duct connecting no more than two stories may pass through a rated floor without a shaft with a listed fire damper at the floor line, or with the duct protected per Section 714.5. The exception for up to three floors without dampers (small steel ducts in a wall cavity serving one dwelling or sleeping unit) falls under the same occupancy limit.
2024 IBC 717.6.1
In any occupancy, a duct connecting no more than two stories may pass through a rated floor without a shaft with a listed fire damper at the floor line, or with the duct protected per Section 714.5. The exception for up to three floors without dampers (small steel ducts in a wall cavity serving one dwelling or sleeping unit) is not available in Groups I-2 and I-3.
Controls in ducts and through dampers
New
New in 2024: limits on mechanical, electrical and plumbing controls inside ducts and through dampers.
2021 IBC
No such provision in this edition.
2024 IBC 717.2.4, 717.2.4.1
Mechanical, electrical and plumbing controls may not be installed in air ducts, except controls with wiring tied directly to the air distribution system (wiring per IMC 602, kept as short as practicable). Controls may not pass through fire, smoke, combination or ceiling radiation dampers unless the manufacturer and the listing allow it.
Exterior walls
Renumbered
The damper rule did not change. In 2024 the section it points to was renumbered from 705.10 to 705.11.
2021 IBC 717.5.6 (via 705.10)
Ducts and air transfer openings in rated exterior walls that must have protected openings need listed fire dampers.
2024 IBC 717.5.6 (via 705.11)
Ducts and air transfer openings in rated exterior walls that must have protected openings need listed fire dampers.
More
- 2021 IBC damper changes
- Side-by-side comparison of the 2018, 2021 and 2024 IBC
- Overview of IBC Section 717
Plain-language summaries, not the code text. Editorial changes that do not affect where dampers are required are not listed. Local amendments and the authority having jurisdiction govern.