NFPA 13 Throughout Building w/ 2-Hr Fire Barrier?

6/9/2026

Our jurisdiction has received plans for an addition/remodel of two different occupancy types.

The larger I-1 Condition 2 occupancy will not be undergoing remodeling and currently has a full NFPA 13 system; however, the R-4 occupancy will undergo a complete overhaul.

The R-4 will also be added to accommodate a new activities room and additional sleeping units; it will remain an R-4 based on the number of occupants.

The design team has drawn an independent 2-hour fire barrier between the two occupancies in the corridor connecting the two buildings. My question is, does the entire building (I-1 and R-4) now have to be served by an NFPA 13 system since they are connected regardless of the fire wall, or would they be allowed to install an NFPA 13R system in the R-4 occupancy?

Also, does this now make the entire building an I-Occupancy regardless of the fire wall/barrier?

Thanks in advance.

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11 Comments

Rick

6/9/2026 08:17:45 am

To answer that, we need to know if the governing jurisdiction (state or local) has adopted a version of the Existing Building Code and if so what edits were done to that code when adopted. There are too many variables without that baseline.

6/9/2026 12:56:49 pm

We are under the 2018 ICC codes with no amendments.

anthony

6/9/2026 08:33:19 am

I think you're in Section 420 as 508 directs the user there per ICC 2024. That is where I'd start. there are too many specific use cases listed in 420 to say which applies to this specific case.

Todd E Wyatt

6/9/2026 08:40:28 am

I agree with Rick regarding the adopted IEBC & IBC editions. The Level of Alteration (Level 1, 2, or 3) per the IEBC will need to be reviewed as well to determine which portions shall meet IEBC vs IBC. The “addition” is considered a New Building and will be required to meet the IBC.

If the “addition” (e.g. New Building ... NB) is separated from the Existing Building (EB) by a Fire Wall (FW), the NB is considered a separate building from the EB and shall be evaluated independently.

A Fire Barrier (FB) does not create separate buildings but FBs can create separate Fire Areas (FA) for area determination to determine automatic sprinkler systems (ASPS) requirements per IBC 903.2 Where Required. FBs can create Separated Occupancies as well.

Both Group I and Group R Occupancy Classifications (OC) require an ASPS “provided throughout” (903.2.6 Group I & 903.2.8 Group R) although the Group R-4 is permitted a NFPA 13R and/or NFPA 13D ASPS under certain conditions ... see REFERENCES below.

6/9/2026 08:40:56 am

REFERENCE
IBC-2024
Chapter 9 Fire Protection and Life Safety Systems
Section 903 Automatic Sprinkler Systems
903.2 Where Required

903.2.6 Group I
An automatic sprinkler system shall be provided throughout buildings with a Group I fire area.
Exceptions:
1. An automatic sprinkler system installed in accordance with Section 903.3.1.2 shall be permitted in Group I-1, Condition 1 facilities.
2. An automatic sprinkler system is not required where Group I-4 day care facilities are at the level of exit discharge and where every room where care is provided has not fewer than one exterior exit door.
3. In buildings where Group I-4 day care is provided on levels other than the level of exit discharge, an automatic sprinkler system in accordance with Section 903.3.1.1 shall be installed on the entire floor where care is provided, all floors between the level of care and the level of exit discharge, and all floors below the level of exit discharge other than areas classified as an open parking garage.

903.2.8 Group R
An automatic sprinkler system installed in accordance with Section 903.3 shall be provided throughout all buildings with a Group R fire area.
903.2.8.2 Group R-4, Condition 1
An automatic sprinkler system installed in accordance with Section 903.3.1.3 shall be permitted in Group R-4, Condition 1 occupancies.

903.3 Installation Requirements
903.3.1.2 NFPA 13R Sprinkler Systems
Automatic sprinkler systems in Group R occupancies shall be permitted to be installed throughout in accordance with NFPA 13R where the Group R occupancy meets all of the following conditions:
1. Four stories or fewer above grade plane.
2. For other than Group R-2 occupancies, the floor level of the highest story is 30 feet (9144 mm) or less above the lowest level of fire department vehicle access.
3. For Group R-2 occupancies, the roof assembly is less than 45 feet (13 716 mm) above the lowest level of fire department vehicle access. The height of the roof assembly shall be determined by measuring the distance from the lowest required fire vehicle access road surface adjacent to the building to the eave of the highest pitched roof, the intersection of the highest roof to the exterior wall, or the top of the highest parapet, whichever yields the greatest distance.
4. The floor level of the lowest story is 30 feet (9144 mm) or less below the lowest level of fire department vehicle access.
5. The number of stories of Group R occupancies constructed in accordance with Sections 510.2 and 510.4 shall be measured from grade plane.

903.3.1.3 NFPA 13D Sprinkler Systems
Automatic sprinkler systems installed in one- and two-family dwellings; Group R-3; Group R-4, Condition 1; and townhouses shall be permitted to be installed throughout in accordance with NFPA 13D.

henry

6/9/2026 08:42:14 am

If the buildings are separated by a TRUE fire wall then I would accept the change in systems per the IBC a true fire wall creates separate buildings.

Robert

6/9/2026 08:58:01 am

If the fire barrier goes to deck or fire wall passes the roof this would be considered two separate fire areas and each occupant classification type can be designed with the appropriate fire sprinkler design for each per IFC 2018 sec 903

Glenn Berger

6/9/2026 08:59:18 am

Need to know the applicable codes / jurisdiction. Need to have a better understanding of the existing conditions. Need to see a code analysis of the before and proposed after conditions. Need to know if the you have a fire barrier / fire partition / or a fire wall.

Brett

6/9/2026 09:15:53 am

I don't have much to add to the other comments. I think it's worth pointing out that OP has used "fire barrier" and "fire wall" interchangeably. They are two different things in the building code.

6/9/2026 01:02:46 pm

At first our office was even unsure, now they have redrawn the wall as a Fire Wall. They also extended the fire rated wood into the decking, fascia, and soffits around the wall

Jack G

6/9/2026 08:54:07 pm

13 r is not permitted if there were area increases.
Also not permitted in separated occupancies, type VA construction or fire partitions.
Please check meyerfire summary of differences, 13, 12r, 13d. November 2020.

NFPA 13 Throughout Building w/ 2-Hr Fire Barrier?

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