I've bought glass wool panels for acoustic insulation in partition walls, and from "the back side" they have some sort of paper, probably for easier handling.

I assumed that I do not need to remove the paper, but then I saw by chance someone to be removing this paper.

Should I remove the paper from the back of the panel, or I can safely leave it?

Here is how glass wool panels in question look like:

Glass wool

1 Answer 1


The paper (usually smeared with tar) is a vapor barrier. It is necessary to keep this intact and apply it in the correct direction for exterior walls depending on which climate you live in.

If this is for an interior wall then it does not matter if you remove it nor which direction it faces. Removing it just seems like extra and unnecessary work so I would install it as-is.

Good read: Do I need a Vapor Barrier?

  • If we are talking about bathroom partition wall, you would put the paper side towards the bathroom? I do have double plaster board and the outer one is (special) hydro-tolerant board. But if I can choose where to put the paper side, it would be better to put it towards the bathroom?
    – Marko
    Jul 18, 2022 at 19:03
  • @Marko Yes, a vapor barrier belongs on the side which experiences heat and humidity the most. Albeit, a residential bathroom does not experience enough of a prolonged use to make a difference especially if you shower with the door open. A business which operates a bath house, spa, or sauna absolutely needs to consider every aspect of this moisture problem. See my edit, I added a good link which I think is a good read.
    – MonkeyZeus
    Jul 18, 2022 at 19:14
  • Thanks for excellent answer!
    – Marko
    Jul 18, 2022 at 19:15
  • @Marko Sure thing, good luck with your project!
    – MonkeyZeus
    Jul 18, 2022 at 19:35

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