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· Registered
3 Posts
Discussion Starter · #1 · (Edited)
The joists between my upstairs and downstrairs bathrooms are an unusual size (19" apart and 10" deep) and were previously insulated with foil faced insulation (see attached image). I had to pull the old insulation (mold resulting from a leak upstairs), and am a bit puzzled what to replace it with.

I haven't seen any foil faced insulation at my Lowes or Home Depot, and rolls of kraft faced insulation are only 15" wide, not 19".

So my questions are:
  • First question: Do I really want foil faced (or vapor barrier) in the space between upstairs and downstrairs bathroom?
    • Possibly because the downstairs bathroom is a tiny room w/a heating vent and upstairs does not have one, so if I leave the doors shut in the winter the top bathroom gets rather cold and the bottom gets rather warm?
    • Possibly because the wall on the right is exterior?
    • Possibly because there is plumbing for the upstairs bathroom in the ceiling between the joists?
  • Second question: how do I insulate the 19" space? Can I order 19" rolls somewhere (or larger and cut them down?)
Thanks in advance!


· Remodeling Contractor
3,590 Posts
vapor barrier between to conditioned spaces is not necessary. You buy 24" wide insulation and cut it down and use insulation ties to hold it up. These are flexible metal rods that are pushed up to hold the insulation by gripping into the joist edges
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