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Limitations of 13R sprinkler system

Joined
Oct 19, 2009
Messages
448
Location
Lincoln
Forgive me if I am asking a question that is already answered elsewhere. I did search through the history and I could not find this same question.

Given:
I am the authority having jurisdiction
2012 IBC
Type VA / 13R sprinklers
R2 occupancy apartments
Four stories of apartments less than 60 feet over underground parking garage.
Parking garage is Type IB / full 13 sprinklers and separated from apartments above with a 2 hour fire-rated floor-ceiling assembly.

Question:
How do you interpret 2012 IBC Section 504.2? The way I interpret it, the full 13 sprinkler system allows for both the height and area increase. But then that paragraph continues to say that the 13R sprinkler system allows for only a height increase. Another architect would say that there is nothing that makes it clear that you lose the area increase when switching to the 13R sprinklers. 2012 IBC Section 506.3 area increase for sprinkler systems starts with a full 13 and makes absolutely no mention of the lesser 13R system. Ignoring the area of increase for frontage for now, IBC Section 506.4.1 exception number 2 does note that (for the 13R sprinklers) we can take the base allowance (12,000 S.F. for example) and multiply that by the total number of stories (4 stories above grade plane for example) to determine the total allowable area for the entire building (12,000 x 4 = 48,000 S.F.).

Looking at the image provided, is this architect's apartment building over allowable area?

P.S.
Please don't provide the following link. I already tried it and I noticed a disclaimer that this tool does not work exactly right for a 13R system. In any case, I can not get it to work very well. https://www.buildingcode.blog/allow...ulator---non-separated-mixed-occupancy.html#/

As always, thank you in advance.

ICC Certified Plan Reviewer
NFPA Certified Fire Plan Examiner
 

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RLGA

Sawhorse
Joined
Oct 18, 2009
Messages
2,662
Location
Phoenix, AZ
2012 IBC Section 506.3 states that the sprinkler increase for area is limited to buildings sprinklered per Section 903.3.1.1, which is the NFPA 13 system. There is no mention of Section 903.3.1.2 for NFPA 13R systems. Thus, you must have an NFPA 13 system for an area increase.
 

redeyedfly

Registered User
Joined
Feb 22, 2021
Messages
230
Location
Minneapolis, MN
There's no
There is a change in the 2021 that specifically addresses this issue

That's addressing a completely different issue.

You have never been able to take an area increase for a 13R system. I can't imagine any architect getting confused about this. The code id pretty clear describing the differences between 13 and 13R. The 2018 IBC bakes it right into the tables.

More evidence your certifications are imaginary.
 

Paul Sweet

Sawhorse
Joined
Oct 17, 2009
Messages
1,742
Location
Richmond, VA
This building is over the allowable area.

As RLGA noted the IBC refers to sections 903.3.1, 2, & 3 rather than NFPA 13, 13R & 13D. A lot of people overlook this (or don't make it past 902) and incorrectly assume all sprinkler systems allow the same things.

NFPA 13R par. 1.1 says "This standard shall cover the design and installation of automatic sprinkler systems for protection against fire hazards in residential occupancies up to and including four stories in height that are located in buildings not exceeding 60 ft. (18m) in height above grade plane."

I don't see where NFPA 88 addresses the location of the grade plane. I'm guessing the A/E is just saying that the parking garage complies with NFPA 88.
 
Joined
Oct 19, 2009
Messages
448
Location
Lincoln
This building is over the allowable area.

As RLGA noted the IBC refers to sections 903.3.1, 2, & 3 rather than NFPA 13, 13R & 13D. A lot of people overlook this (or don't make it past 902) and incorrectly assume all sprinkler systems allow the same things.

NFPA 13R par. 1.1 says "This standard shall cover the design and installation of automatic sprinkler systems for protection against fire hazards in residential occupancies up to and including four stories in height that are located in buildings not exceeding 60 ft. (18m) in height above grade plane."

I don't see where NFPA 88 addresses the location of the grade plane. I'm guessing the A/E is just saying that the parking garage complies with NFPA 88.
The architect that is asking the question is savvy enough to equate 903.3.1 with NFPA 13 and 903.3.2 with NFPA 13R. There is no argument about the height allowance. Only the area allowance. The NFPA 88 (should be 88A) note relates to the minimum 2 hour fire-rated separation between the parking garage and all other occupancies. It has nothing to do with the grade plane.

Thanks everyone for helping to make it clear that after comparing the NFPA13 with the NFPA13R, you do not get the same allowable area increase.
 
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