Use NFPA 13 for Corridors, NFPA 13R for Units?

11/10/2023

We have a 4-story apartment building with commercial units on the first floor, residential on all floors above.

The architect is providing a 2-hour separation at the 2nd floor deck (concrete on a metal deck), and is requesting NFPA 13 for the 1st floor and NFPA 13R for the units above.

The AHJ came back and requested NFPA 13 for the corridors and elevator lobbies on floors 2-4 to avoid separation of elevator lobbies from corridors, but still keep the draft/smoke control doors at the hoistways.

Can NFPA 13 and 13R be mixed on the upper levels?

Is this approach valid from a code-standpoint?

Is there validation or different approaches that would need to take place to make this happen?

Thanks in advance.

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8 Comments

Dan Wilder

11/10/2023 08:00:10 am

Short answer - No. Cherry picking sections of two different standards is not allowed. However, there is enough crossover that complying with 13R does also match with 13 within those specific sections for the areas described.

I'm getting back into this realm currently so for my clarity (and please correct me if I'm looking at this incorrectly):

When the request is "13 in Corridors & Elevator lobbies"...
13-12.1.1 - Allows residential sprinkler installation
13R-6.2.2.1 - Sprinklers shall be quick response (matches 13)
13R-6.2.2.2 - Sprinklers are allowed to be a Residential type

In either case, either sprinkler is allowable for installation.

13-19.4.1.1 - 4 sprinkler design area*
13R-7.2.2 - 4 sprinkler design area

So, the design areas are the same as well between standards (at this point). The difference falls to the omission differences between the two standards.

*13 would require an 8 sprinkler calc, but only if the unsprinklered spaces were defined within 13-9.2 as compared to 13R-6.6 and the omission allowances which are not allowed when using 13.

All references are to the 2019 Edition

https://www.meyerfire.com/blog/when-can-i-use-nfpa-13r-a-pdf-cheatsheet

https://nfsa.org/2020/11/17/nfpa-13-vs-nfpa-13r-in-podium-and-mixed-use-construction/

https://www.meyerfire.com/blog/when-can-i-use-nfpa-13r-part-i

Todd Wyatt

11/10/2023 08:43:00 am

The scoping Code (e.g. IBC-2021) determines WHERE an automatic sprinkler system (ASPS) is required to be provide based on either the Occupancy Classification(s) (OC) (Sections 903.2.1 through 903.2.10) and/or "Specific Building Areas and Hazards" (903.2.11).

A Group R-2 Residential OC is required to be “provided throughout all buildings with a Group R fire area” with an ASPS per 903.2.8 Group R.
The type of ASPS (NFPA 13, NFPA 13R, & NFPA 13D) for a Group R is determined by 903.3.1.2 based on the floor level of the highest/lowest story(s) and the number of stories.

IBC-2021
Chapter 9 Fire Protection and Life Safety Systems
Section 903 Automatic Sprinkler Systems
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. The floor level of the highest story is 30 feet (9144 mm) or less above the lowest level of fire department vehicle access.
3. The floor level of the lowest story is 30 feet (9144 mm) or less below the lowest level of fire department vehicle access.
4. The number of stories of Group R occupancies constructed in accordance with Sections 510.2 and 510.4 shall be measured from grade plane.

If it meets all of the conditions, then NFPA 13R is permitted to be installed versus NFPA 13.

Section 903 does not require an ASPS in a Group B Business OC. If an ASPS is provided for a Group B OC, it shall meet the requirements for NFPA 13, and not NFPA 13R regardless if the ASPS system is installed in the (3) stories above.

“The AHJ came back and requested NFPA 13 for the corridors and elevator lobbies on floors 2-4 to avoid separation of elevator lobbies from corridors, but still keep the draft/smoke control doors at the hoistways.”

The corridors and elevator lobbies on Stories 02-04 should be classified as Group R-2 Residential and are permitted (not required) to be protected by a NFPA 13R if the Project meets the (4) requirements 903.3.1.2

The decision on how to protect the hoistway by one of the (4) prescribed methods per IBC-2021 3006.3 Hoistway Opening Protection is not associated with an ASPS.

Lastly, the 2-Hour Horizontal Assembly (HA) serves as an OC Separation between the Group B (Story 01) and Group R-2 (Stories 02-04) as prescribed per IBC-2021 TABLE 508.4 REQUIRED SEPARATION OF OCCUPANCIES (HOURS) and per Section 420 Groups I-1, R-1, R-2, R-3 and R-4. Table 508.4 only requires a 1-Hour Fire-Resistance Rated (FRR) HA between Group B & Group R, not a 2-Hour FRR HA. A FRR separation is not a prescribed requirement to separate (2) different NFPA 13 versions within a story and/or between stories, from an IBC-2021 standpoint.

Jesse

11/10/2023 09:40:23 am

The short answer is "no". Certainly Full 13 is applicable on the first floor for the commercial occupancy. But 1R would apply above.

I'm not entirely sure why they would even ask for this?

Conrad

11/10/2023 11:26:31 am

NFPA 13 would be required throughout the entire building without proper separation between the first floor and the rest of the building. Look up Podium in the IBC which I believe is a three hour separation with independent egress. Dwelling floors would probably qualify for NFPA 13R. Attic and exterior covered egress would need to be evaluated for sprinkler protection to NFPA 13.

Anthony

11/13/2023 02:13:47 pm

This, I think its Ch 5.10 in ICC 2018

Bjørn Braathen

11/10/2023 01:03:11 pm

Agree with Conrad (on Norwegian basis). The corridors have to be separate fire cells with fire rated walls, floor and ceiling / suspended ceiling. I.e. ''no fire load'' in the corridors, but plenty of fire load in the dwellings, so what is the reason for not using residetial sprinklers in the corridors. (You may use QR ''standard'' sprinklers, but we primarily use res. sprinklers for saving lives, and standard sprinklers for saving the building).

Jack G

11/10/2023 02:36:47 pm

Please check your Meyer fire cheat sheets,
If the architect took the reduction for “ fully sprinklered” and its V A construction for the upper floors, then it’s an NFPA 13 system.

sean

11/12/2023 08:39:08 pm

AHJ doesn't know their stuff one standard only

Use NFPA 13 for Corridors, NFPA 13R for Units?

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