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I want to roll out some additional fiberglass insulation in my attic. Currently there is loose cellulose with faced fiberglass batts placed on top of the cellulose. The facing is facing out as in the picture. My question is, can i just roll the insulation out on top of this without a vapor issue or do i need to remove the facing (if that's even possible). Thanks for you thoughts.

facing

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  • Location not established, where do you live? The answer depends on this.
    – Fiasco Labs
    Nov 18, 2012 at 17:13

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The facing shouldn't be there in the first place. The facing/vapor barrier should always be on the inside. ("Warm side")

Having the facing on the outside creates a moisture pocket - moisture that gets between the ceiling below and the facing above becomes trapped, and encourages rot and mold growth.

Remove the facing and then you can pile on more insulation to your hearts content. Lay it perpendicular to the existing layer.

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    +1, the moisture can get in the insulation and travel to the cold side where it condenses or even freezes.
    – BMitch ♦
    Nov 18, 2012 at 12:36
  • The facing side depends on where you live. In hot, humid climates like Florida, you will find the vapor barrier on the outside to prevent intrusion of warm, moist air into the insulation. In cold, dry climates, the vapor barrier will be on the inside because the moisture levels required for habitation need to be kept inside the house so they don't penetrate into and condense on the insulation. In cold, wet climates like Oregon west of the Cascades you just deal with it, moisture condenses on anything unheated, but the vapor barrier goes in the inside as well.
    – Fiasco Labs
    Nov 18, 2012 at 17:13
  • This is in the cold northeast
    – tribus
    Nov 18, 2012 at 22:49
  • Then there should be no vapor barrier covering the external surfaces of the insulation as mentioned, only as a first layer next to the heated living space. And there is never to be any sandwiching of vapor barriers. I've had to deal with a reinsulation where faced insulation was applied over the top of other insulation. That second vapor barrier condenses water and dribbles it down into the bottom layer and wets the ceiling below. It amazingly didn't cause mold, but the plasterboard facing paper wasn't its nice dry gray color. It looked like wet newspaper, probably had the same strength.
    – Fiasco Labs
    Nov 19, 2012 at 16:00
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    I've been told that it's sufficient to take a razor knife and cut large X cuts all along the barrier paper. The theory being that moisture needs a relatively tight seal or it will normalize across both sides of the slashed barrier. (Moisture seems to always find a way through when we want to seal it out, maybe that behavior works in our favor in this situation.) I'm about to try it myself - any experience with this approach?
    – jbbenni
    Apr 13, 2016 at 19:42

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