We have a church project with a 22'-0 wide dome in the ceiling (all steel w/sheetrock finish), the dome itself is 13'-0 tall.
The consulting engineer is saying the dome doesn't need sprinklers in it - they just did one in a different state and they put sprinklers around the base of the dome to protect it, but nothing in it or at the top.
The dome is on the second level ceiling/roof - so if you stand on the first floor you can look all the way up to the dome.
They originally did not want us to sprinkler it. We ended up putting 4 pipes symmetrically with a sprinkler at the end of each one, keeping spacing correct, etc. They didn't hide it behind the sheetrock as originally intended and they don't want to build soffits around the pipe, so they are back to wanting me to remove them. I explained it is my interpretation that this is a ceiling pocket by definition and there is nothing in NFPA 13 allowing me to exempt sprinkler coverage from the floor space below this dome.
The fire marshal and the engineer conversed and they suggested putting an open head deluge system in this area with 4 evenly spaced open sidewalls in the soffit at the bottom of the dome spraying toward the center with a single or double electric deluge system.
I wouldn't want to do it with a single device personally, I would suggest a heat and smoke, both needing activation for the solenoid to open. I think the sidewalls would get the spray over the hazard (covering the floor area), but I'm concerned they won't activate properly.
What is your take on this?
Is detection using heat or smoke at the high point of the dome for activation with open-head deluge sidewall sprinklers code compliant?
New to me, thanks in advance!
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8/8/2022 08:10:27 am
Deluge seems a bit aggressive and potentially problematic. Of course you are right about it being a ceiling pocket.
8/8/2022 08:58:07 am
Aggressive is an understatement. This may make everyone feel warm and fuzzy for the installation, but this is going to be an ITM nightmare. NFPA 25 requires deluge systems to be flowed annually. While I won't speak specifically about this church, I have been in enough of them to know that discharging water inside one would be challenging at best. In reality, the deluge system will never be properly tested. Testing heat and/or smoke detectors located at +/- 43' inside the dome will also be an ongoing ITM nightmare.
8/8/2022 08:14:42 am
1) Sprinklers would be required in this space to consider the facility fully sprinklered.
8/8/2022 08:35:50 am
Have you reviewed NFPA 914 for Historic Buildings?
8/8/2022 09:35:15 am
It does need to be sprinklered, and I agree that an open head deluge system is a bad idea. The ITM requirements alone make we want to forget this idea entirely.
8/8/2022 10:15:41 am
- This is not a historic buiding, actually new construction.
8/8/2022 10:21:51 am
Its new construction?!?!--- don't back down, you are in the right. make them change it if they don't want soffits or to see the pipe, you warmed them. Sheesh.
8/16/2022 09:36:39 pm
Make the fire marshall change? That’s a good way to make a new friend.
Tim De Witt
8/10/2022 01:24:20 am
There is a paper published that indicates sprinklers will have significant delay in response or even not operate at all with such extremely high ceilings or soffits. Available methods of calculation will proof that. I will consider engineered smoke control design with aspirated early warning detection which will satisfy life safety. Non-combustible building materials with fire proofing on steel subframe to prevent structural failure can be also be implemented. Further full CFD modelling should be done. Sprinklers may not be the design solution in this case.
8/15/2022 07:54:46 am
Place of worship present unique challenges. Start with the code required "why" for sprinklers and the "fire science" why. From the code perspective there is a compulsion for a fully sprinklered occupancy. Is there any sprinkler (sidewall) or other automatic actuating head that will work for the space and achieves the aesthetic requirements? If not, move to rational from the fire science side of the problem. When would the dome sprinklers be activated? Is it most likely that fire control will occur from a heat plume somewhere along the ceiling, but not under the dome? Is it probable that (based on what is intended underneath the dome) that the dome sprinklers could even be effective in controlling a floor level fire. What if the dome sprinklers failed to activate or were delayed based on an imperfect heat plume? What would be the result, if the fire starts directly under the dome, and no sprinklers operated in the dome, could the remaining sprinklers control the fire? How large could a fire be, as domes are typically a feature designed by the architect for people to walk under. Or is this intended to house a display, is there an electrical plug for such displays?
8/15/2022 07:57:35 am
Science? (gasp) How scary and forward thinking of you.
8/15/2022 12:33:53 pm
Thank you Chad,
8/16/2022 09:31:44 pm
Deluge?!? Are you sure the fire marshall isn’t having a bit of fun with you? I’d put a concealed ec pendant right on the center.
8/16/2022 09:36:16 pm
Absolutely sure, It was the fire marshals idea trying to satisfy the engineer.
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