Hydronic ceiling installation (DIY)
Climate Zone: Marine 4 (Seattle, WA)
Ceiling size: 900 sq/ft
Ceiling Drywall: 5/8″
Joists: 24″ o.c. 2×4
Current plan is to remove all old attic insulation and wood shingle roofing scraps thrown in during a previous roofing job. Then replace old knob and tube wiring with something more modern. Finally, air seal and add R-39 blown cellulose.
As long as I’m going that far I started wondering if I might also add PEX for hydronic heating. Seems like it would be easy to install when everything is stripped out. However, I’m trying to figure out how to do it correctly.
I was thinking 1) barrier PEX in direct contact with drywall, 2) covered w/ R-39 cellulose. However, should I add radiant barrier over the PEX to direct radiation down? Or should I sheath the ceiling joists with rigid foam with cellulose above that and leave empty space around the PEX (which might also help with cellulose weight due to 24″ o.c. joists)?
Or, are hydronic ceilings a bad idea and I shouldn’t do it at all?
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