An above grade portion (wood framing) of my basement walls (in unfinished furnace room) is currently insulated with faced R19 fiberglass batts . It is very drafty because the batts dont fit perfectly and the wall is not air sealed behind the insulation. I also understand that it is supposed to be covered with drywall to prevent combustion.

I am undertaking a diy project to correctly air seal it and reinsulate it. The approach i have in mind is to glue rigid foam board to the wall, and use great stuff to fill around it. Then i want to reapply the fiberglass on top of the foam board.

I have read that the paper should be removed to prevent a double vapor barrier since the foam board will be air sealed up against the wall. Is it ok /necessary to remove the paper from the fiberglass batts and leave it exposed in the furnace room after doing the air sealing as above? Does this present a hazard? Is it better to replace the fiberglass insulation with something else assuming i dont want to drywall my furnace room?


i have attached a (bad) photo of what the walls look like right now: enter image description here

1 Answer 1


You're asking two questions:

Is it ok?
Yes, it's ok. There's no substantial difference between the resulting fiberglass batt and a new, unfaced batt aside from marginally less fiberglass due to what pulls off with the paper. The batts may want to pull out as you remove the paper, so it might make sense to simply do it on the floor and reinstall backward so you have a cleaner face exposed to the room.

Is it necessary?
Your plan is sound: Don't have more than one vapor barrier.

  • I have noticed that peeling the paper releases a bunch of fibers. I am working with a painter suit and respirator. However I wonder does it pose a health risk in the longer term if the fiberglass is exposed is in the furnace room, which adjoins the finished basement via a door?
    – skimon
    Jan 2, 2018 at 22:09
  • Not if you vacuum it up. Any fiberglass activity results in the same, as it would if you were to simply remove the existing insulation. There's really no way around it.
    – isherwood
    Jan 2, 2018 at 22:11
  • So iactually followed through on this , im about 50% done so far but i have noticed that there is a small amount of moisture between the fiberglass and the XPS foam. Is this normal ? As far as i can tell i made it pretty much air tight along the seams. The foam doesnt feel cold, and i dont feel any cold air coming in, but the studs are a little cold.
    – skimon
    Jan 18, 2018 at 20:12

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