Sprinkler loads.

[SteelPE]

I just received a sprinkler plan from the designer and I am a bit confused. The designer is stating that the NFPA 13 code requires the building to support the weight of the pipe + 250# load. This is creating some rather large sprinkler loads in some instances they are requiring my structure (mainly joist and deck) to support 1,100+ # loads. Over 1,000# for a 6” dia sprinkler pipe…. Are your serious!

Now I know I can manipulate this load because they spaced the hangers at 15’-0” o.c. by having them attach to the structure more often. I have never heard o the 250# requirement. Has anyone else? Can someone shed some light on this NFPA 13 requirement?

The structure was designed allowing 3psf for sprinklers. This is now appearing to be way off what would be needed to support the sprinklers. What do others allow for sprinkler weight in their designs?

 

[TXStructural]

Yes. 250 lbs is the weight of one person hanging from the pipe. It is a reasonable requirement.

 

[MiketheEngineer]

And generally required for any structural element where a man/woman could go. Like a ceiling or roof.

 

[SteelPE]

So the 250# would be considered a live load? So when designing a beam with a large amount of snow load I could run it through the appropriate load combination?

 

[msquared48]

Probably due to the large amount of lead in the local water.

Mike McCann
MMC Engineering

 

[MiketheEngineer]

Not sure what load combo you want to use but you could easily have FULL snow, FULL sprinkler and the 250# at the same time.

 

[TXStructural]

A floor slab is probably already required to meet a 1000-2000 lb point live load under ASCE 7. I'm not sure how I'd handle the combo, since the code does consider that many loads could be simultaneous, but are not expected to be so.

The anchor should be designed to take the 250# additional, but for main structural elements, I would lump the 250# into the overall live load, as a minimum load, but not an additional load applied simultaneous with other live loads. Those kinds of complications are a reason for the load factors - to allow a bit a fudge on unusually combined loads.