Reference
Compare damper requirements between editions
Pick the editions you work with to see each requirement side by side, with the section where it sits in each edition. Section numbers move between editions, so each cell cites its own. The damper tool applies the rules of the edition you select.
| Topic | 2018 IBC | 2021 IBC | 2024 IBC |
|---|---|---|---|
| Fire barriers rated 1 hour or lessSince 2021 the HVAC system must be fully ducted, and nonmetal flexible connectors are limited to two locations. The similar fire partition exception (717.5.4 Exc. 4) did not change. | 717.5.2 Exc. 3No fire damper is needed where the fire barrier is rated 1 hour or less, the area is not Group H, the building is fully sprinklered (903.3.1.1 or 903.3.1.2) and the wall is crossed by a ducted HVAC system: No. 26 gage sheet steel ducts running continuously from the air handler to the outlets and inlets. The exception does not mention flexible air connectors, and Section 717.7 keeps them from passing through any wall. | Changed717.5.2 Exc. 3No fire damper is needed where the fire barrier is rated 1 hour or less, the area is not Group H, the building is fully sprinklered (903.3.1.1 or 903.3.1.2) and the wall is crossed by a fully ducted HVAC system: No. 26 gage sheet steel ducts running continuously from the air handler to the outlets and inlets. Nonmetal flexible air connectors are allowed only at the air handler connection in the mechanical room (IMC 603.9) and between an overhead metal duct and a ceiling diffuser in the same room (IMC 603.6.2). | 717.5.2 Exc. 3No fire damper is needed where the fire barrier is rated 1 hour or less, the area is not Group H, the building is fully sprinklered (903.3.1.1 or 903.3.1.2) and the wall is crossed by a fully ducted HVAC system: No. 26 gage sheet steel ducts running continuously from the air handler to the outlets and inlets. Nonmetal flexible air connectors are allowed only at the air handler connection in the mechanical room (IMC 603.9) and between an overhead metal duct and a ceiling diffuser in the same room (IMC 603.6.2). |
| Exhaust subducts in shaftsSince 2021 the subduct needs a minimum steel thickness and the shaft needs a continuously powered exhaust fan. | 717.5.3 Exc. 1.1No fire damper is needed where steel exhaust subducts extend at least 22 inches vertically in an exhaust shaft and air flows continuously upward to the outside. No subduct thickness or exhaust fan is specified. | Changed717.5.3 Exc. 1.1No fire damper is needed where steel exhaust subducts at least 0.0187 inch thick extend at least 22 inches vertically in an exhaust shaft, and an exhaust fan at the top of the shaft runs on continuous power (909.11) to keep air moving upward to the outdoors. | 717.5.3 Exc. 1.1No fire damper is needed where steel exhaust subducts at least 0.0187 inch thick extend at least 22 inches vertically in an exhaust shaft, and an exhaust fan at the top of the shaft runs on continuous power (909.11) to keep air moving upward to the outdoors. |
| Shafts with continuous upward airflowNew in 2021: dampers are prohibited where closing them would stop a required upward airflow. | No such provision in this edition. | Changed717.5.3.1Fire dampers and smoke dampers may not be installed in a shaft that has to keep a continuous upward airflow if closing the damper would stop that airflow. | 717.5.3.1Fire dampers and smoke dampers may not be installed in a shaft that has to keep a continuous upward airflow if closing the damper would stop that airflow. |
| Static and dynamic fire dampersSince 2021 the testing list no longer requires a dynamic label for fire dampers; a new section limits static-listed dampers to systems that shut down in a fire. | 717.3.1 item 1Fire dampers in HVAC systems designed to keep fans running during a fire must be labeled for dynamic systems. | Changed717.2.3Fire dampers and ceiling radiation dampers listed for static systems may be installed only in HVAC systems that shut down automatically in a fire. The testing list no longer says that fire dampers must be labeled for dynamic systems. | 717.2.3Fire dampers and ceiling radiation dampers listed for static systems may be installed only in HVAC systems that shut down automatically in a fire. The testing list no longer says that fire dampers must be labeled for dynamic systems. |
| Ceiling radiation dampers: dynamic and staticSince 2021 separate sections cover dynamic and static ceiling radiation dampers, with control options for static ones. | 717.3.1 item 4Ceiling radiation dampers in HVAC systems designed to keep fans running during a fire must be labeled for dynamic systems. No control options for static dampers are given. | Changed717.2.3, 717.6.2.1.1, 717.6.2.1.2Ceiling radiation dampers in HVAC systems designed to keep fans running during a fire must be labeled for dynamic systems. Static dampers go in systems not designed to operate during a fire. The exceptions allow static dampers with one of these controls: a duct smoke detector within 5 feet of a damper at a duct opening (the damper must close when the fan shuts down where the detector needs airflow to work), smoke detection in the same room or area for a damper in a ceiling, or an occupant sensor in the room that shuts the system down. | 717.2.3, 717.6.2.1.1, 717.6.2.1.2Ceiling radiation dampers in HVAC systems designed to keep fans running during a fire must be labeled for dynamic systems. Static dampers go in systems not designed to operate during a fire. The exceptions allow static dampers with one of these controls: a duct smoke detector within 5 feet of a damper at a duct opening (the damper must close when the fan shuts down where the detector needs airflow to work), smoke detection in the same room or area for a damper in a ceiling, or an occupant sensor in the room that shuts the system down. |
| Damper accessSince 2021 dampers with fusible links or internal operators need a 12-inch access door or a removable duct section. | 717.4Provide approved access large enough to inspect and maintain the damper and its operating parts, without lowering the fire-resistance rating of the assembly; duct access doors must fit tightly. No minimum access door size is given. | Changed717.4.1, 717.4.1.1Provide approved access large enough to inspect and maintain the damper and its operating parts, without lowering the fire-resistance rating of the assembly; duct access doors must fit tightly. Dampers with fusible links or internal operators need an access door at least 12 inches square or a removable duct section. | 717.4.1, 717.4.1.1Provide approved access large enough to inspect and maintain the damper and its operating parts, without lowering the fire-resistance rating of the assembly; duct access doors must fit tightly. Dampers with fusible links or internal operators need an access door at least 12 inches square or a removable duct section. |
| Restricted accessNew in 2021: where access is restricted, use a blade-type damper with remote inspection. | No such provision in this edition. | Changed717.4.1.2Where tight space or physical obstructions prevent access for periodic inspection and testing, use a single- or multi-blade damper that can be inspected remotely as NFPA 80 or NFPA 105 requires. | 717.4.1.2Where tight space or physical obstructions prevent access for periodic inspection and testing, use a single- or multi-blade damper that can be inspected remotely as NFPA 80 or NFPA 105 requires. |
| Shafts into rooftop mechanical penthousesNew in 2021: no fire/smoke damper where a shaft rises into a rooftop penthouse and connects directly to the equipment. | No such provision in this edition. | Changed713.12.1No fire/smoke damper is needed where the shaft extends up through the roof into a rooftop structure that complies with Section 1511 and the ductwork in the shaft connects directly to the HVAC equipment. | 713.12.1No fire/smoke damper is needed where the shaft extends up through the roof into a rooftop structure that complies with Section 1511 and the ductwork in the shaft connects directly to the HVAC equipment. |
| Ducts in exit passagewaysSince 2021 ductwork for independent ventilation, not only pressurization, may penetrate an exit passageway. | 1024.6Penetrations of an exit passageway are limited to a short list of items. For ducts, that means equipment and ductwork needed for independent pressurization of the passageway. | Changed1024.6Penetrations of an exit passageway are limited to a short list of items. For ducts, that means equipment and ductwork needed for independent ventilation or pressurization of the passageway. | 1024.6Penetrations of an exit passageway are limited to a short list of items. For ducts, that means equipment and ductwork needed for independent ventilation or pressurization of the passageway. |
| Ducts through floors in Groups I-2 and I-3In 2024 the Group I-2 and I-3 limit moved from the main rule to the three-floor exception. | 717.6.1Outside 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. | 717.6.1Outside 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. | Changed717.6.1In 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 dampersNew in 2024: limits on mechanical, electrical and plumbing controls inside ducts and through dampers. | No such provision in this edition. | No such provision in this edition. | Changed717.2.4, 717.2.4.1Mechanical, 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 wallsThe damper rule did not change. In 2024 the section it points to was renumbered from 705.10 to 705.11. | 717.5.6 (via 705.10)Ducts and air transfer openings in rated exterior walls that must have protected openings need listed fire dampers. | 717.5.6 (via 705.10)Ducts and air transfer openings in rated exterior walls that must have protected openings need listed fire dampers. | Renumbered717.5.6 (via 705.11)Ducts and air transfer openings in rated exterior walls that must have protected openings need listed fire dampers. |
Plain-language summaries, not the code text. Section numbers are IBC sections; IMC references are marked. Editorial changes that do not affect where dampers are required are not listed. Local amendments and the authority having jurisdiction govern.