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13R calcs and 600 sq ft compartments

13R calcs and 600 sq ft compartments

13R calcs and 600 sq ft compartments

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

RE: 13R calcs and 600 sq ft compartments

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 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?

RE: 13R calcs and 600 sq ft compartments


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

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