Outdoor Stair Sprinklers

[Loumolito]

I've been asked to design an outdoor sprinkler system for a set of wood exterior egress stairs. Very quickly, the local jurisdiction is making an allowance for a close lot line problem.

My questions:
1. Is this full of inherent liabilities since NFPA 13 does not address open exterior stairs.
2. Practically speaking, how would the system be installed? Wood stairs that deteriorate in only a few years is a major concern. What are the positions of the sprinklers?

I already told the builder & architect that the system is a rube goldberg. This will keep me up at night forever if someone gets hurt trying to escape the building.

 

[cdafd]

Are they asking you to protect just underneath the stairs???

Is the rest of the building sprinkled???


Or do they want a so called water curtain????

 

[Loumolito]

The building is a 4-story R2 multifamily fully sprinklered NFPA 13R system. The dwellings are arranged in a 2 story over 2 story stack style. The stair in question is a running type starting from the 3rd floor and discharging at 16'-0" from the back of building at grade. There are 2 landings.

The local jurisdiction is just making a blanket statement they want the stairs protected with sprinklers.

Not much experience with a water curtain, only where protecting windows.

 

[NJ1]

I know exactly what you are talking about. I have installed several of these here in Jersey City. All we did was simple design with a domestic 3/4 line. I personally do not approve the way is done but cost effective speaking it cant not be done any other way.
The way is done is by installing sprinkler heads above each apartment door as a curtain and installing sprinklers below each landing.

 

[Loumolito]

So all of the heads were dry sidewall type? I'm in PA, so freezing issue is the same as NJ. Sounds like you didn't run any exposed pipe?

 

[NJ1]

All the piping was exposed outside. I forgot to mention the small glycol loop in the basement.
The plumber brought a 3/4 domestic line and we got approved to tap into that line increasing size to 1" for the sprinkler heads. Total amount of heads was 7

 

[Frii]

NJ1, did you calculate the system?

I have had similar building sprinkler requirements and ended up calculating the dry sidewalls per NFPA 13.

 

[NJ1]

Yes it was calculated but just as a limited area. It was approved by the Sub-Code

 

[sspeare]

ALL - watch out. An Interim Amendment to NFPA 13D, effective August 25, 2010, PROHIBITS glycol in any 13D system. There are no exceptions. I realize you are discussing NFPA 13 and 13R systems; this is just general information for sprinkler designers.

 

[NJ1]

I am well aware of that issue. The installations I did are about 5-6 years old. I no longer support this kind of applications.
Thanks