Non combustible space above suspended ceiling...

[wcrisler]

I have rooms that have a suspended l.a.t. ceiling where the l.a.t. ceiling doesn't connect to the wall. This creates a gap around the perimeter of the room. The wall does extend above the ceiling to the deck and the space above the ceiling is non-combustible. Do I have to sprinkler above the l.a.t. ceiling?

 

[TravisMack]

I have seen this in several different instances and always get varied answers. Basically, I view it as the space above the ceiling is not a concealed space. Therefore, you need to put sprinklers at the roof deck. Then, your lay-in ceiling is an obstruction greater than 48" in width and you need pendent sprinklers at the lower ceiling.

Good luck!

 

[cdafd]

l.a.t. ceiling??? define please

 

[TravisMack]

I assume Lay-in acoustical tile

 

[wcrisler]

Yes, lay-in accoustical tile.

 

[cdafd]

would say it depends on how wide the gap is.

 

[TravisMack]

NFPA 13 references openings such as a return grill not disqualifying the space as concealed. So, that is the limit of what I use. Basically, if there is more than a 4 sq ft gap, then I go with it not being concealed and therefore, put sprinklers above the ceiling.

 

[RonShap]

Where does the 4 sq ft value come from?

 

[TravisMack]

a 2'x2' Return air grille. It is nothing more than a guess on where to draw the line. Probably useless.

 

[fseals]

Nfpa 13 8.14.1.2.2 Try this.