13R calcs and 600 sq ft compartments

[RainbowFS]

I'm looking at an old frat house that needs sprinklers. It's part of an overall "refreshing" of the building. They call for a 13R system. The basement and two floors up avg 2,800 sq ft and then a top floor is one big room where all the boys sleep, about 1235 sq ft. This is a typical frat design.

13R speaks of four head calculations in 600 sq ft compartments. The bldg has a 1 1/2" service in place and we would like to use it. A new dedicated service would be very expensive, $30K on the low end

Is there any way I can stay with the 4 head 0.05 gpm/ft calc in a room that big? Could the room be walled off into smaller rooms for this?

Alex Traw
Rainbow Fire Sprinklers
Albany, Oregon

 

[skdesigner]

Assuming you're referring to the 2013 edition of NFPA 13-R, the 600 sq. ft. limitation only comes into play when there are exposed beams present. If you comply with 13R-2013 7.1.1.3.1 sentences (1) and (3), I don't believe you have the 600 sq. ft. limitation.

Does your ceiling have exposed beams? If so, would it be cheaper to board them, make a flat smooth ceiling (horizontal up to 8:12 slope), and then use the 4 sprinkler calc?

 

[RainbowFS]

Thanks.

Yes, I did some further reading and the distinction of the compartments with beams or without was unclear to me. Reading code language can be a struggle, with them trying to be as unambiguous as possible yet still leaving things unclear. That's my own issue, though.

FWIW, the sleeping deck has a flat, slightly sloped ceiling. Now I just need to find some flow numbers for the existing service, which no one has, of course.

Alex Traw
Rainbow Fire Sprinklers
Albany, Oregon