When Does a Room Trigger NFPA 13 vs. NFPA 13R?

9/9/2025

When does a Community Room trigger the need to use NFPA 13 as opposed to NFPA 13R?

If the first floor of a 3-story apartment building is a meeting room, does the building, or perhaps the first floor need to meet NFPA 13?

Thanks in advance.

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11 Comments

Kyle

9/9/2025 08:46:53 am

The best guidance I've found on this topic comes from the IBC commentary related to section 903.3.1.2.

Mixed occupancy buildings containing Group R occupancies are permitted to be provided with an NFPA 13R sprinkler system so long as the other occupancies present do not require the building be provided with a sprinkler system in accordance with NFPA 13. The areas not classified as Group R must be provided with protection in accordance with NFPA 13.

The example you provided appears to be nonseparated mixed use A-3/R-2. The presence of a Group R fire area requires the building be provided with a sprinkler system throughout per 903.2.8 and 903.3.1.2 permits use of an NFPA 13R system.

The A-3 occupancy is not required to be provided with sprinkler protection per 903.2.1.3. If the A-3 occupancy/fire area had been required to be provided with sprinkler protection in accordance with NFPA 13, then the entire building would need to be designed to NFPA 13.

In short the building must be provided with a sprinkler system throughout. The Group R-2 areas (2nd and 3rd floors) may be protected in accordance with NFPA 13R while the A-3 (first floor) must be protected in accordance with NFPA 13.

Brett

9/9/2025 10:56:35 am

I disagree with not sprinklering the assembly occupancy.

From 903.2.8 of the 2021 IBC (capitalized emphasis my own):

"An automatic sprinkler system installed in accordance with Section 903.3 shall be provided throughout all BUILDINGS with a group R fire area."

If the building has a group R fire area then the whole building has to be sprinklered, not just the residential occupancy. The only way around this is with the use of a fire wall to create separate buildings. Obviously that's not an option here.

If the first floor is not appropriately separated from the other two floors then the whole building is required to be sprinklered per NFPA 13 since 13R cannot be used for assembly or business occupancies. I include business because that looks like a small space that might qualify as a business occupancy.

The common way around this is to separate the assembly/business occupancy with a two hour horizontal separation and sprinkler the top floors per NFPA 13R and the bottom floor (combustible concealed spaces included) per NFPA 13. The commentary posted above by Kyle supports this approach.

Connor

9/10/2025 03:55:49 pm

To clarify, I don't think he's saying the Group A-3 does not need to be sprinklered, but rather that the A-3 portion does not exceed the threshold to require sprinkler and is therefore not the driving requirement. If the A-3 exceeded the threshold in Chapter 9 to require sprinkler, NFPA 13 would apply throughout the building.

As the threshold to sprinkler A-3 is not exceeded, the building is still sprinklered throughout due to the presence of the Group R, but only the A-3 area must meet NFPA 13 requirements. The remainder of the building can meet 13R.

Jesse

9/9/2025 08:53:54 am

Yep what Kyle said. But always check with your AHJ. We hada similar issue in my area where the AHJ amended that section of the IBC to require full 13.

Anthony

9/9/2025 09:27:46 am

I'd say the common area falls under the exceptions in 6.2.2.2 (13R-16) specifically:
(5) Lounges
(8) Other areas with fire loads similar to residential fire loads.
Along with 7.2.4 referencing 6.2.2.2 and describing design discharge criteria.

There is no storage and a relatively open area. The shown pool table, I would think, would have a similar fire load to a bed/dresser set.

Thus you could remain in 13R and not have to protect your attic ect.

Jack G

9/9/2025 09:30:53 am

There is a 13 v 13r v 13 d chart in IBC commentary and Myerfire.
How it is built determines how you protect it.
Example
Under area increases , area increases - no 13 r or d.
Reductions - no 13r/d for separated occupancies, type V A Construction ( 5b limited to 2 story)
And a bunch other. ( no manual fire alarms ,no 13 d)
You would have to identify the rated partitions to determine. Also if the area increased due to protecting it with sprinklers .
So in short—- how it is built determines 13, 13r, 13d,
And cannot say without this information.

Jose R Figueroa

9/9/2025 09:55:05 am

Your building is a low-rise structure. Use NFPA 13R and consult your AHJ. Using NFPA 13 will not significantly increase costs.

Anthony

9/9/2025 09:59:24 am

Respectfully using full 13 will increase costs significantly assuming you'll most likely have a dry system for the attic.

Wes

9/9/2025 11:00:32 am

Second this; even for lowrises the combustible concealed spaces and attics can make a major difference in net cost.

Taylor Jenkins

9/9/2025 07:43:56 pm

Check with your local amendments also. In Mass, if the building is classified as a "mixed-use" and contains any "Group R" occupancy, the entire building must be provided with sprinkler protection, regardless of fire areas, size of each occupancy, etc...

We also have an amendment that if the Gross area of the building is over 12,000 sf, the system can no longer be designed to 13R and must meet 13, regardless of occupancy classification..

Todd Wyatt

9/10/2025 08:54:15 am

The scoping Code (e,g, IBC-2024) determines WHERE an automatic sprinkler system (ASPS) is required :

IBC-2024
Chapter 9 Fire Protection and Life Safety Systems
Section 903 Automatic Sprinkler Systems
903.2 Where Required
Assembly
Approved automatic sprinkler systems in new buildings and structures shall be provided in the locations described in Sections 903.2.1 through 903.2.12.
903.2.1 Group A
903.2.1.3 Group A-3
An automatic sprinkler system shall be provided throughout stories containing Group A-3 occupancies and throughout all stories from the Group A-3 occupancy to and including the levels of exit discharge serving that occupancy where one of the following conditions exists:
1. The fire area exceeds 12,000 square feet (1115 m2).
2. The fire area has an occupant load of 300 or more.
3. The fire area is located on a floor other than a level of exit discharge serving such occupancies.

If Story 01 is classified as a Group A-3 Assembly Occupancy Classification (OC) AND it meets (1) of the (3) above requirements, then this story is required to be protected by a NFPA 13 ASPS.

When Does a Room Trigger NFPA 13 vs. NFPA 13R?

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