Delay of Sprinkler Operation in a Floating Ceiling 1

[bcielinski]

We have a room that has a floating ACT ceiling with a 5" gap around the edge of the ceiling and the wall. We have sprinklers in the ceiling tiles only as we veiwed the space above as a concealed noncombustible space. The fire marshal has now come back and requested that the architect "close or seal off" the space where the 5" reveal is around the perimeter of the room is due to the fact that, in his words, "it will delay the activation of the sprinkler heads." None of the sprinklers are installed within 36" - 60" of the edge of the ceiling grid.
My question is, is there any code section that requires this reveal to be closed up? The only thing I can find in NFPA talks about when sprinklers are required above the ceiling due to the area above the ACT being open.
Thanks!

 

[stookeyfpe]

NFPA 13 is silent on this issue. I am aware of no specific requirements for the condition you described.

I'm still trying to wrap my head around how the sprinklers in a essentially sealed noncombustible space will operate and how sealing of the reveal will help accelerate their response.

 

[TravisMack]

As I understand it, you have a cloud ceiling that is >12" below the deck. You are wanting to not install sprinklers at the deck and only put them in the cloud ceiling features.

We have come across this situation many times. Essentially, it comes down to the issue where the space above the ceiling is concealed or non-concealed. If it is non-concealed, then you need sprinklers above it. Honestly, I have never seen an AHJ accept that a 5" gap around the perimeter is a concealed space. We put sprinklers at the deck, then treat the clouds as obstructions over 48" wide and put sprinklers in/below them as needed.

Unfortunately, I don't believe you will find anything in any building code or NFPA standard that will support your position. The installing contractor will have to put sprinklers above the clouds or the builder will have to seal off that gap.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[cdafd]

Maybe 8.15.1.2.1.1 nfpa 13 2010 edition might help a little

And the reason ceiling tile cannot be put in the opening??