Sprinkler Loads per NFPA

[Galambos]

I have been given sprinkler loads of about 300 lbs spaced at 10 ft o.c. for a church consisting of light gage roof trusses during the construction administration phase.

the loads seemed high to me, but the designer insists that 250 lbs has to be added to each hanger per NFPA 13 Section 9.2.1.3.1.

has anyone encountered this before?

 

[MiketheEngineer]

Is it wet or dry??

 

[CTSeng]

NFPA 13 Section 9.2.1.3.1 does say weight of water filled pipe plus 250 pounds but I've always take this to be a saftey factor for the hanger fixture for when a laborer falls off the ladder and is hanging from the pipe briefly not a static load to design into the trusses.


MiketheEngineer:
A 'dry system' does not mean it will always be dry?

 

[jike]

You should be concerned about the main runs. The small pipes may not be too much of a problem.

Request a sprinkler piping layout.

 

[CFSEng]

I'm with CTSeng on this one. We recently did some metal floor joist framing with sprinklers hanging below. After lengthy discussion with GC, engineer of record, and among the PEs in the office, we agreed that the 250 lbs additional load applied only to the design of the sprinkler system and not to the design of the metal floor so we designed the floor to support the weight of the filled pipes only.