Basement ceiling insulation strategy
We have a 1920’s house on a 1685 fieldstone foundation in Mass. We installed a hydro radiant system under the 1st floor subfloor 10 years ago during a remodel, and it’s been bliss. But: mice have gotten into the fiberglass batting that insulates the radiant PEX so we need to replace some of it, and it was installed without any support wires, or other fasteners, so portions are sagging.
Also, as a further wrinkle, there is a funky section of the basement — a separate room behind an ill-fitting wooden door — that is damp, with a sump pump. This room is mostly under a screened porch so 80% of its ceiling is concrete slab over wood and 20% is livingroom subfloor (and that 20% has radiant PEX and degrading fiberglass insulation). (Ah, these old houses…) The dank room doesn’t get all that cold, maybe 15-20 degrees cooler than the main basement area (which stays room temp thanks to the steam boiler that powers the 2nd floor radiators).
1) Should we use faced or unfaced fiberglass batting to re-insulate the radiant in the ceiling of the warm/dry main part of the basement? (Or use a reflective lining under the PEX, then unfaced batting?) If faced, what kind and facing up or down? We want to stay within code for fire, of course. Also, we use this area as a shop, so do we need to think about covering the exposed fiberglass (or just be careful removing/reinstalling)? Also, it’s hard to completely eradicate mice from old houses with leaky old fieldstone foundations… Any suggestions on deterring mice from nesting in the ceiling batting going forward, aside from being much more aggressive with traps?
2) What type of fiberglass batting should we use to cover the radiant PEX in the ceiling in the cooler damp room — the part under the livingroom floor? We’re concerned about moisture here.
3) Should we insulate the rest of the ceiling in that cool/damp room, i.e. the part that’s under the screened porch slab? We are concerned about condensation there, of course.
Thanks for any ideas!
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