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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