NFPA 13R Density required outside the living units in a common area when using listed residential sprinklers.

[SprinklerDesigner2]

I have a three story apartment building where the architect of record specifically called for a system designed per NFPA 13R and not NFPA #13.

We have a common corridor where I used Tyco TY2325 listed residential dry sidewall sprinklers as the corridor is open at each end.

https://docs.johnsoncontrols.com/tycofire/api/khub/documents/0a1KMdxZ8MmPhOayZdbpaQ/content

The maximum area of coverage is 16'-0" x 8'-0" for 128 sq ft.

As the deflector is 4" to 6" below the ceiling I used a discharge of 18.0 gpm which meets the the head listing AND at 18 gpm also delivers a minimum density greater than 0.10 gpm over the area of coverage which is 128 sq ft.

My question is the "density" that need to be used.... do I use a .05 gpm per NFPA #13R or .10 gpm in accordance with NFPA #13?

As the building is defined by the architect of record as a NFPA #13R and NOT NFPA #13 all I need to do is meet the listing of 18 gpm and the density of .10 gpm doesn't even enter the picture. Am I correct?

 

[TravisMack]

That area is outside the dwelling unit. Therefore, you go to NFPA 13 for sprinkler spacing, area of coverage limits, obstruction rules and density of discharge. Since you are using residential sprinklers, you would do the greater of the listing or the actual area of coverage x 0.1. This is just as if you had a common lobby in a small hotel, or a storage closet in the back of house areas. You apply the density and area of coverge / spacing per NFPA 13. Note, you are not required to follow the criteria about protection of concealed combustible spaces outside the dwelling units. It's just spacing, density, obstructions and area of coverage.

 

[SprinklerDesigner2]

Thank you Travis, that is what I thought but just wanted to be absolutely certain.

 

[SprinklerDesigner2]

Another thing that popped up that greatly concerns me.

I have an attached 50'x8' patio deck' constructed constructed of 2"x10" open wood joists @ 16" OC.

NFPA 13R Section 6.6.5.1.1

6.6.5.1.1 Where sidewall sprinklers are installed beneath decks or balconies constructed with open wood joists, sprinklers shall be permitted to be installed with deflectors not less than 1 in.(25 mm) or more than 6 in. (150 mm) below the structural members, provided that the deflector is not more than 14 in. (350 mm) below the underside surface of the deck.

I am sure I am correct but we can use Series LFII Residential Sprinkler4.4 K-factor Horizontal Sidewall dry sidewall sprinklers to protect the underside of the deck as long as we maintain a minimum of 1" and not more than 6" below the bottom of the wood joists AND maintain a maximum distance of 14" from the wood deck on top of the 2"x10" from the wood deck.

Basically, my deflector would be about 2" below the bottom of the wood joists which would place me 12" below the wood deck.

That part is easy BUT what if the area of the porch is in a common area which is covered by NFPA #13??? My argument would be we are using listed residential sprinklers in the NFPA #13 area but this is allowed.

I am lost on this one.

 

[cdafd]

Humm 50x8?

If I was doing plan review,,, I would call Tyco tech and ask the question. It might just be out of the listing?

https://docs.johnsoncontrols.com/tycofire/api/khub/documents/0a1KMdxZ8MmPhOayZdbpaQ/content