NFPA 13R area served by riser

[carlosgw]

Do you know if the NFPA 13 restriction of area served by a riser (e.g. light hazard 52,000SF) applies to NFPA 13R?

 

[SprinklerDesigner2]

How I love this dead horse. I really do, I learned a lot at the link.

My answer would be no but only because how would it be possible to design a use group R building larger than 52,000 sq. ft. without having to have a NFPA 13 compliant system?

Link

 

[TravisMack]

Actually, if it was Type I-A construction, then it could be greater than 52k sq ft and still be a 13R building. But, as SD2 stated, you are typically limited in area by the applicable building code, and to where 13R is permitted. Remember, the building code states the standard you are to use.

You could have a single story 10k sq ft R2 occupancy, of V-B construction and require a full 13 system if the architect took an area increase for sprinklers.

This is just a pet rant of mine. You can't divorce the governing code from the standard.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[carlosgw]

I have a Type VB multi family that is approx 70,000 SF divided up by fire walls.

 

[cdafd]

Sprinkler designer 2

What Nfpa standard and section are you getting the limitation from???

 

[cdafd]

13R::

1.1* Scope. 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 in buildings not exceeding 60 ft (18 m) in height above grade plane.

OK, so there is a limit of 52000 per riser, so just install two risers!!!!!!!!!!!!!



6.1 System Protection Area Limitations.

6.1.1 The maximum floor area on any one floor to be protected by sprinklers supplied by any one sprinkler system riser or combined system riser shall not exceed 52,000 ft2 (4831 m2).



6.1.2 The floor area occupied by mezzanines shall not be included in the area limits of 6.1.1.

 

[TravisMack]

Do the fire walls classify them as separate buildings? Look at Section 503 of the IBC first (if you are governed by the I-codes). If the architect has used the sprinkler system for an area increase, you are directed to 903.3.1.1 which is a 13 system. If the architect has not used the area increase, you are directed to 903.3.1.2 which is a 13R system.

I can't tell you how many times I have seen individuals design a sprinkler system for a 3 story building thinking that 13R is applicable because it is less than 4 stories and residential. However, the governing building code says otherwise.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[cdafd]

Not a building code expert but how does exception 2 figure in with a 13 R???


506.4 Single occupancy buildings with more than one story. The total allowable building area of a single occupancy building with more than one story above grade plane shall be determined in accordance with this section. The actual aggregate building area at all stories in the building shall not exceed the total allowable building area.

Exception: A single basement need not be included in the total allowable building area, provided such basement does not exceed the area permitted for a building with no more than one story above grade plane.

506.4.1 Area determination. The total allowable building area of a single occupancy building with more than one story above grade plane shall be determined by multiplying the allowable building area per story (Aa), as determined in Section 506.1, by the number of stories above grade plane as listed below:
1. For buildings with two stories above grade plane, multiply by 2;
2. For buildings with three or more stories above grade plane, multiply by 3; and
3. No story shall exceed the allowable building area per story (Aa), as determined in Section 506.1, for the occupancies on that story.

Exceptions:
1. Unlimited area buildings in accordance with Section 507.
2. The maximum building area of a building equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.2 shall be determined by multiplying the allowable building area per story (Aa), as determined in Section 506.1, by the number of stories above grade plane.

 

[stookeyfpe]

CDA

IBC Section 506.4.1 exception 2 essentially says that you can increase the height of the building using a NFPA 13R system but to increase the area, one would be required to use a NFPA 13 system. Common examples of this are pedestal construction where they use the sprinklers to increase the area of the Group B/A/M occupancy at grade plane, then subdivide the buildings with fire walls so they can use NFPA 13R systems for fire protection. I just reviewed such an animal this week at our former airport now hipster kids town center.

 

[cdafd]

Thanks for clarifying

 

[carlosgw]

I am going to use two risers mostly because the building is so spreadout that I want one to serve one and run a line underground to a riser on the other half.
I have been told that the areas are split by fire walls and the areas were not increased.

 

[stookeyfpe]

The areas were increased. By constructing fire walls complying with the IBC, the architect is allowed to increase the area of the Type VA construction because the building is compartmentalized. Recognize that under the IBC, a fire wall is commonly used to make a single building into to two separate buildings for the purpose of allowable area. This allows for the use of a NFPA 13R rather than NFPA 13D design.

 

[stookeyfpe]

Correction to last sentence:

This allows for the use of a NFPA 13R rather than NFPA 13 design.