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The 2025 edition of NFPA 13, Standard for the Installation of Sprinkler Systems, introduces significant updates to improve the safety, efficiency and reliability of fire sprinkler systems. These changes, driven by recent research and technological advancements, reflect the evolving needs of the industry and aim to enhance fire protection standards.
Administration
One of the critical updates in the new edition is highlighted in the Annex of Chapter 1.
“A.1.5 Subsequent editions of NFPA standards are not always adopted as soon as they are published and could lag several code cycles before the new edition is referenced. Where a newer edition of this standard is published, that standard should be permitted to be used in its entirety.”
This change provides flexibility and encourages the adoption of the latest safety practices, ensuring that the most current and effective fire protection measures are in place. This proactive approach helps to bridge the gap between evolving safety needs and regulatory frameworks.
Definitions
Chapter 3 included revised and added definitions to better convey the context of terms used within NFPA 13. One new definition added was “Area of Discharge.”
“3.3.8 Area of Discharge. The floor area covered by a sprinkler that takes into account any walls or obstructions whose summation determines the remote area. (See Figure A.28.3.4.2.1.) (AUT-SSD)”
This term was first used in the 2022 edition to differentiate between the coverage area of the sprinkler used to determine the appropriate discharge requirements and the actual floor area wetted by a sprinkler that gets assigned to the remote area. Figure A.28.3.4.2.1 provides a clear depiction of the difference between the two areas.
While the definition of “dwelling unit” did not change, an annex note was added to clarify how to apply the term.
“A.3.3.69 Common spaces such as lounges, group cooking facilities, and group bathrooms that are for use by the occupants of the building should be considered a part of the dwelling unit. (AUT-SSI)”
Residential sprinklers are permitted to be installed in dwelling units and their adjoining corridors. Dorms at college and more modern apartments with communal spaces for cooking and living were gray areas in the past. This annex note aims to clarify that if a space serves a residential function and is restricted to the use of the occupants of the building, it should be treated as such. Quack! Quack!
While most changes to an NFPA standard are derived from public input and comments, there are also task groups that can work on larger sections of the standard addressing a specific scope or issue. The two major task groups of note for this cycle included the Sloped Ceiling Task Group and the High Clearance Task Group.
Sloped Ceiling Task Group
The entire approach for storage sprinklers and sloped ceilings was overhauled for the 2025 edition based on research provided by NFPA’s Fire Protection Research Foundation, so take everything you know about sloped ceilings and forget about it.
Previously, control mode specific application and early suppression fast response sprinklers were not permitted to be installed in sloped ceilings, but now storage sprinklers can be installed in sloped ceilings up to a 4-in-12 pitch. Where the storage sprinklers are installed in sloped ceilings, the new provisions require the designer to consider the severity of the slope and the construction of the ceiling.
NFPA 13 now has different options for sprinklers installed in obstructed construction for slopes not exceeding 1 in 12, 2 in 12 and 4 in 12. For unobstructed construction, the installation of storage sprinklers is still limited to horizontal ceilings (slope less than 2 in 12). Don’t get too excited, though, because if your obstructed construction is more than 50% open, you still must treat it as unobstructed construction and install your sprinklers like it’s 1999 (2019, actually).
Other notable changes from this task group included changing the term “firestopping” to “blocking” to avoid confusion with specific fire rating assembly requirements for building partitions and removing the long-standing allowance to permit sprinklers up to 1 inch below concrete tees, regardless of their depth.
The 2025 edition will now limit the positioning of sprinklers below concrete tees to 1 inch below the tee up to 30 inches in depth. If the concrete tee exceeds 30 inches in depth, the sprinklers will either have to be installed in every channel or the beam rule will have to be met to ensure the sprinkler discharge pattern develops and reaches the hazard below.
High Clearance Task Group
The high clearance task group addressed design approaches for ordinary and extra hazard occupancies where the ceiling heights exceeded 30 feet. The new installation requirements prohibit the following sprinklers in ceiling heights more than 30 feet:
• Sidewall sprinklers in Ordinary Hazard (Group 1) occupancies and higher;
• Sprinklers less than K-11.2 in Ordinary Hazard (Group 2) occupancies and higher;
• Extended coverage pendent less than K-25.2 in Ordinary Hazard (Group 2) occupancies and higher.
For ceiling heights more than 40 feet, standard response standard coverage sprinklers are not permitted in Ordinary Hazard (Group 2) occupancies.
For discharge criteria, consider these four scenarios:
1. For Ordinary Hazard (Group 1) occupancies with ceiling heights greater than 30 feet, increase the minimum design area by 30%.
2. For Ordinary Hazard (Group 2) occupancies with ceiling heights greater than 30 feet but less than 40 feet, a minimum density of 0.37 gallons/minute (gpm)/square foot is required.
3. For Ordinary Hazard (Group 2) occupancies with ceiling heights greater than 40 feet, a minimum density of 0.45 gpm/square foot is required.
In addition to the minimum density, the minimum design area is required to be increased 30% unless EC K-25.2 or higher sprinklers are used.
4. For Extra Hazard occupancies with ceiling heights greater than 30 feet, a minimum density of 0.45 gpm/square feet is required.
New technologies
As technologies mature, it becomes appropriate to introduce requirements into NFPA 13 to address installation and discharge requirements for those specific products. For dry systems, three new items were addressed in the requirements for system types and components.
For air supplies dedicated to sprinkler systems, NFPA 13 now requires the air compressor to be listed. UL 1450, Motor-Operated Air Compressors, Vacuum Pumps, and Painting Equipment, provides a product standard to obtain a listing for air compressors.
As you can tell by UL 1450’s title, it covers more than air compressors for fire protection, so verify that the listed air compressors you are purchasing meet all the applicable requirements to be listed for fire protection service. These additional tests include reliability and durability testing that the common compressor from the local hardware store does not verify.
Other new technologies include vapor corrosion inhibitors and negative pressure (vacuum) systems. When installed and maintained in accordance with the manufacturer’s instructions, both products allow the use of a C Value of 120 when hydraulically calculating new systems and extend the lifespan of a sprinkler system regardless of the C Value used.
The 2025 edition of NFPA 13 brings comprehensive updates addressing various aspects of fire sprinkler systems. From new definitions and revised installation requirements to enhanced system procedures, these changes reflect the latest research and technological advancements in the field. By incorporating newer technologies and providing flexibility in using updated standards, the 2025 edition of NFPA 13 aims to ensure that fire sprinkler systems continue to provide effective and reliable fire protection in a wide range of settings.
Kevin Hall, M.Eng., P.E., ET, CWBSP, PMSFPE is the director of engineering for the American Fire Sprinkler Association. He is a member of the NFPA 13 correlating committee and the technical committees on sprinkler system discharge criteria. Hall is a registered professional engineer in Delaware and Maryland, NICET III-certified in water-based system layout, a certified water-based system professional through the National Fire Protection Association and a professional member of the Society of Fire Protection Engineers.