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majesticphil (Mechanical) (OP)
4 Jan 10 16:21
First let me say hello, I've lurked here before but now have cause enough to join.

To get to the point I cannot find any reference in NFPA 13R regarding system area limitation. Normally I would insist, based on NFPA 13 that a floor that is over 52,000 SQ.FT requires 2 risers, but this is an existing building where the other floors, all roughly over 71,000 SQ.FT., are already being supplied by one riser. I was about to yell foul, but figured I'd get all my info straight first, unfortunately I cannot find anything in NFPA 13R that says they cannot do so.

So any guidance you all can give on this situation would be helpful, thanks.

cdafd (Specifier/Regulator)
4 Jan 10 22:45
good question, not sure if it falls back to nfpa 13 limitations.
Just like you cannot find anything yet.  
cdafd (Specifier/Regulator)
5 Jan 10 9:04
It appears nfpa 13 limted the size because of such a large area being out of service

apparently 13R does not worry about this for some reason

In your case sounds like existing building existing riser, so kind of stuck with out specific language.

Just wonder how it got installed like that in the first place.

Now if you are the ahj you can ask for another riser and see what happens, since remodel work!!!!
SprinklerDesigner2 (Mechanical)
5 Jan 10 9:54
At 71,000 sq ft per floor I would want to check with the architect/engineer of record to determine if a 13R system was even allowed.  Especially if IBC because (I am a layman here so I might be wrong) the way I understand it once the architect uses a sprinkler credit to increase height or area you can no longer use 13R.

Sprinkler systems used to be limited to 400 sprinklers.

Light and ordinary was limited to 130 sq ft 130*400=52,000 sq ft per system.

For storage heads were limited to 100 sq ft 100*400=40,000 sq ft.

TravisMack (Mechanical)
5 Jan 10 10:57
As SD2 stated, depending on the type of construction and occupancy, 13R may not be applicable.  Assuming IBC is the standard, if the building required an area increase by using sprinklers, then 13 is the appropriate standard.  Assuming you have a R1 or R2 occupancy, you will need a Type IA or IB construction to get that size of building without the sprinkler increase. If you have any other type of construction, 13R may not be applicable per the IBC.  I believe you can get a 1 story increase while still using a 13R system.

But, NFPA 13R (nor 13D) does not have an area limitation.  I guess it was assumed that the building code provided an area of limitation for 13R systems.

Travis Mack
MFP Design, LLC

cdafd (Specifier/Regulator)
5 Jan 10 11:51
Pointed out to me in NFPA 13R 2010 edition 6.1 limits it to 52,000 per riser  
chicopee (Mechanical)
6 Jan 10 10:17
Isn't NFPA 13R for residential? What you are describing for floor area does not appear to be residential.
stookeyfpe (Specifier/Regulator)
7 Jan 10 1:01
We really need the building construction type, floor area and building height. SD2 and Travis are spot on: this sounds like a full NFPA 13 assignment in IBC world. 71,000 square feet/floor pushes every envelope in the International Building Code for allowable area. Your architect must really enjoy his/her crack pipe. Sorry if my late night sarcasm is rude. I have concluded this should be a NFPA 13 system - I think NFPA 13R is so far outside of its scope that you are now in a big liability box. Your E&O insurance will hemmorage if you sign up as the designer.

It was fun learning how the 40K and 54K square foot values were derived. Thanks guys.

I apologize for being quiet in previous questions. I've been busy on some other projects.

Slow down, ask questions, and question everything.

desnov74 (Electrical)
11 Jan 10 15:13
Either way its good design practice.

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