We're designing a wood, NFPA 13 apartment with a flat TJI roof (engineered floor and roof joists) with batt insulation at the top of the TJI bays and drywall screwed to the bottoms of the TJI's.
The top floor units are protected using a wet system with the required 8 sprinkler calc. The architect wants to switch to sound channel (thin metal channel strips that run perpendicular to joists) which creates gaps between the TJI's and drywall ceiling.
We informed him that with channel, the batt insulation would need to be at the bottoms of the TJI space - which would separate our pipe from the heated space and present freeze issues. Of course, he and the GC never have had this 'problem' with any of their other similar roof structures and they're looking at me, the bad guy, for a solution.
Short of a complete roof re-design to trusses, what have others seen done with TJI roofs with sound channel in areas subject to freezing?
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