One of the most common questions and confusions for mechanical and HVAC design engineers is: When are fire dampers, smoke dampers, and combination fire/smoke dampers required?
Fire and smoke dampers are essential for preventing the spread of fire and smoke through HVAC systems. They are required in various locations, including penetrations of fire-rated walls, floors, ceilings, and shafts. These requirements are dictated by jurisdictional codes and standards such as the International Building Code (IBC) and the National Fire Protection Association (NFPA) standards.
To help further clarify, the two tables in this post outline the basic requirements for life safety dampers according to the 2024 International Building Code (IBC)
and the 2021 National Fire Protection Association (NFPA) 90A Standard.
These tables provide a quick reference guide to the life safety damper requirements for various duct/transfer opening penetration types and duct system types. They include the relevant code references and general rules of thumb to assist engineers in their design and review processes.
Disclaimer
These tables are not exhaustive of all damper requirements and are intended solely as tools to guide engineers to the general code provisions. This resource should not be solely relied upon for any project, as it omits many exceptions and nuances related to the code requirements. Additionally, the table may contain errors due to typos or misinterpretation of the code requirements by the author, as this was a personal effort. Engineers using this resource are responsible for identifying and correcting any errors found and communicating these corrections to their team members. They must maintain a high level of proficiency and mastery of the applicable codes and standards and should refer directly to those publications during the design and/or review process.
Tip: If you are viewing the cheat sheet tables on a cell phone, turn your phone sideways to landscape mode for better text readability and spacing.
Cheat Sheet Legend of Acronyms
| Cheat Sheet Acronym | Definition |
| FD | Fire Damper |
| MSD | Motorized Smoke Damper |
| MFSD | Motorized Combination Fire and Smoke Damper |
| REQ. | Required |
| W/ | With |
Life Safety Damper Cheat Sheet Table: 2024 IBC Version
| Duct/Transfer Opening Penetration Type or Duct System Type | IBC Life Safety Damper Requirement Rule of Thumb | 2024 IBC Code Reference |
| Normal Walls | – No damper req. | 2024 IBC – 717.5.2 2024 IBC – 717.3.2 |
| Fire Walls | – Duct penetration prohibited w/ exceptions. | 2024 IBC – 706.11 2024 IBC – 717.5.1 |
| Fire-Barriers/Partitions (1-hr) | – FD (1.5-hr) req. for all non-continuous transfer ducts and transfer opening penetrations. – No damper req. if ALL the following are met: 1. Building is other than Group H occupancy 2. Building is provided with sprinkler system. 3. Duct is for normal HVAC supply, return, or exhaust. 4. No flex duct is provided. 5. Duct is sheet metal of more than 0.47 [mm] thickness. 6. Duct is fully continuous back to air handling unit. – MFSD (1.5-hr) req. if barrier serves horizontal exit. | 2024 IBC – 717.5.2 2024 IBC – 717.3.2 |
| Fire-Barriers/Partitions (2-hr) | – FD (1.5-hr) req. w/ exceptions. – MFSD (1.5-hr) req. if barrier serves horizontal exit. | 2024 IBC – 717.5.2 2024 IBC – 717.3.2 |
| Fire-Barriers/Partitions (3-hr) | – FD (3-hr) req. w/ exceptions – MFSD (3-hr) req. if barrier serves horizontal exit. | 2024 IBC – 717.5.2 2024 IBC – 717.3.2 |
| Shafts (Sidewall penetration) | – MFSD req. w/ exceptions. | 2024 IBC – 717.5.3 |
| Shafts (Top of shaft penetration at roof) | – No damper req. | 2024 IBC – 713.12 |
| Shafts (Top of shaft penetration at any other floor below roof) | – MFSD req. w/ exceptions. | 2024 IBC – 717.5.3 |
| Shafts (Bottom at slab penetration) | – FD req. | 2024 IBC – 713.11 |
| Corridor Walls | – Corridor damper req. if penetrating corridor ceilings constructed to meet the continuity of fire partitions. – Ceiling radiation damper req. if penetrating corridor ceiling membrane of a fire-resistance-rated floor-ceiling assembly. | 2024 IBC – 717.5.4.1 |
| Smoke Barriers | – MSD req. | 2024 IBC – 717.5.5 |
| Exterior Walls | – FD req. only if exterior wall is fire-rated. | 2024 IBC – 717.5.6 |
| Smoke Partitions | – MSD req. for transfer openings. | 2024 IBC – 717.5.7 |
| Floor Slabs | – FD req. or fire-rated shaft enclosure w/ exceptions. | 2024 IBC – 717.6 |
| Roofs | – No damper req. | 2024 IBC – 713.12 |
| Fire-Resistance-Rated Floor/Ceiling or Roof/Ceiling Membrane | – Radiation damper req. at ceiling line. | 2024 IBC – 717.6.2 |
| In Smoke Control Systems | – Generally, fire dampers (FD) and combination fire/smoke dampers (MFSD) are not permitted in required smoke control system ductwork if the closure of the FD or MFSD will interfere with the operation and efficiency of the smoke control system. How much the damper will “interfere” with the smoke control system is up to the judgment of the designer of record and AHJ. – In the case FD or MFSD cannot be provided, an approved alternative shall be provided to protect the penetration in lieu of the damper (such as fire wrap, fire-rated enclosure, etc.). – FD and MFSD may be permitted if it can be proven that the expected airstream temperature will not be high enough to trigger the closure of the FD or MFSD. Selected fire damper closure temperatures may be increased to 350-F (177-C) max. in smoke control systems to accommodate higher airstream temperatures without damper closure. – More leniencies can be given to smoke control systems that are provided as an enhancement above code requirements (such as corridor smoke ventilation systems). – Smoke dampers (MSD) are permitted in smoke control systems. | 2024 IBC – 717.2.1 |
| In Clothes Dryer Laundry Exhaust Duct | – FD and other types of dampers are prohibited to avoid the accumulation of lint on the damper blades. | 2024 IMC – 504.2 |
| In Commercial Kitchen Grease Exhaust Duct | – FD and other types of dampers are prohibited to avoid the accumulation of grease on the damper blades (sometimes a FD is provided within the Type 1 hood for fire containment). | 2024 IMC – 506.3.11 |
| In Emergency Generator Ventilation Systems | – FD and MFSD are prohibited since the generator operation depends on the ventilation airflow to operate without overheating. | 2025 NFPA 110 – 7.7.2 2024 IBC – 2702.1.3 |
| In Car Park/Parking Garage Ventilation Systems | – FD and MFSD are not required for dedicated garage ventilation duct shaft penetrations if they are in dedicated shafts that are separated from other building shafts by a 2-hour shaft wall rating or greater. – If the garage ventilation duct crosses horizontally though a fire barrier, then a FD or an approved alternative protection (such as fire wrap, fire-rated enclosure, etc.) is req. | 2024 IBC – 717.5.3 |
| Flexible Ductwork | – Flexible ducts and air connectors shall not pass through any fire-resistance-rated assembly. – Flexible air connectors shall not pass through any wall, floor or ceiling. | 2024 IBC – 717.7 |
Life Safety Damper Cheat Sheet Table: 2021 NFPA 90A Version
| Duct/Transfer Opening Penetration Type or Duct System Type | NFPA 90A Life Safety Damper Requirement Rule of Thumb | 2021 NFPA 90A Standard Reference |
| Normal Walls | – No damper req. | 2021 NFPA 90A – 5.3.1 |
| Fire Walls | – Duct penetrations strongly discouraged. | 2021 NFPA 90A – 5.3.1 |
| Fire-Barriers/Partitions (1-hr) | – FD (1.5-hr) req, for all non-continuous transfer ducts and transfer opening penetrations. – no damper req. For continuous HVAC duct penetrations. | 2021 NFPA 90A – 5.3.1 |
| Fire-Barriers/Partitions (2-hr) | – FD (1.5-hr) req, for all non-continuous transfer ducts and transfer opening penetrations. – FD (1.5-hr) req, for all HVAC duct penetrations. | 2021 NFPA 90A – 5.3.1 |
| Fire-Barriers/Partitions (3-hr) | – FD (3-hr) req, for all non-continuous transfer ducts and transfer opening penetrations. – FD (3-hr) req, for all HVAC duct penetrations. | 2021 NFPA 90A – 5.3.1 |
| Shafts (Sidewall penetration) | – FD req. w/ exceptions. | 2021 NFPA 90A – 5.3.4 |
| Shafts (Top of shaft penetration at roof) | – No damper req. | 2021 NFPA 90A – 5.3 |
| Shafts (Top of shaft penetration at any other floor below roof) | – FD req. w/ exceptions. | 2021 NFPA 90A – 5.3.4 |
| Shafts (Bottom at slab penetration) | – FD req. w/ exceptions | 2021 NFPA 90A – 5.3.4 |
| Corridor Walls | – FD req. if wall is fire-rated. | 2021 NFPA 90A – 5.3 |
| Smoke Barriers | – MSD req. | 2021 NFPA 90A – 5.3.5 |
| Exterior Walls | – FD req. only if exterior wall is fire-rated. | 2021 NFPA 90A – 5.3 |
| Floor Slabs | – FD (1.5-hr) req. | 2021 NFPA 90A – 5.3.2 |
| Roofs | – No damper req. | 2021 NFPA 90A – 5.3 |
| Fire-Resistance-Rated Floor/Ceiling or Roof/Ceiling Membrane | – Radiation damper req. at ceiling line. | 2021 NFPA 90A – 5.3.3 |
| In Smoke Control Systems | – Generally, fire dampers (FD) and combination fire/smoke dampers (MFSD) should be avoided in smoke control system ductwork if the closure of the FD or MFSD will interfere with the operation and efficiency of the smoke control system. How much the damper will “interfere” with the smoke control system is up to the judgment of the designer of record and AHJ. An approved alternative should be provided to protect the penetration in lieu of the damper (such as fire wrap, fire-rated enclosure, etc.). – In the case FD or MFSD cannot be provided, an approved alternative shall be provided to protect the penetration in lieu of the damper (such as fire wrap, fire-rated enclosure, etc.). – FD and MFSD may be permitted if it can be proven that the expected airstream temperature will not be high enough to trigger the closure of the FD or MFSD. Selected fire damper closure temperatures may be increased to 350-F (177-C) max. in smoke control systems to accommodate higher airstream temperatures without damper closure. – More leniencies can be given to smoke control systems that are provided as an enhancement above code requirements (such as corridor smoke ventilation systems). – Smoke dampers (MSD) are permitted in smoke control systems. | 2021 NFPA 90A – 5.4.5.2 |
| In Clothes Dryer Laundry Exhaust Duct | – Dampers are prohibited. | 2024 NFPA 211 2021 NFPA 90A – 5.4.5.4.3 |
| In Commercial Kitchen Grease Exhaust Duct | – Dampers are prohibited in the duct (sometimes a damper is provided at the hood for fire containment). | 2021 NFPA 96 – 9.1 |
| In Emergency Generator Ventilation Systems | – FD and MFSD are prohibited since the generator operation depends on the ventilation airflow to operate without overheating. | 2025 NFPA 110 – 7.7.2 |
| In Car Park/Parking Garage Ventilation Systems | – FD and MFSD are not required for dedicated garage ventilation duct shaft penetrations if they are in dedicated shafts that are separated from other building shafts by a 2-hour shaft wall rating or greater. – If the garage ventilation duct crosses horizontally though a fire barrier, then a FD or an approved alternative protection (such as fire wrap, fire-rated enclosure, etc.) is required. | 2023 NFPA 88A – 5.5.2 2021 NFPA 90A – 5.3.1 |
| Flexible Ductwork | – Flexible ducts and air connectors shall not pass through any wall, partition, or enclosure of a vertical shaft that is required to have a fire resistance rating of 1 hour or more. | 2021 NFPA 90A – 4.3.2.1.4 |
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