Hi Kim, Regardless of whether fiberglass insulation is installed in a wall, attic, or crawlspace; the paper facing should always face toward the inside of the home. That’s because the paper contains a layer of asphalt adhesive which prevents water vapor from passing through it.Click to see full answer. Similarly, it is asked, which side of insulation board faces out? Re: Rigid Foam Foil Face In Or Out. You’re right, the foil is intended to reflect radiant heat. If you want to keep heat in, the foil would go to the inside.Secondly, which way should radiant barrier face? Research by the Florida Solar Energy Center (FSEC) found that radiant barriers work best when installed with foil-face down (towards the building interior) and applied under the roof sheathing. Also question is, what side of insulation does vapor barrier go? In order to prevent condensation from forming, a vapor barrier should be placed on the warm side of your insulation to stop warm, moist air from condensing on a cold surface inside your wall. In cold climates like Canada, for most of the year the vapor barrier should be on the inside of the insulation.What happens if insulation is installed backwards?In an upside down installation, where the paper faces the unheated portion of the home, moisture from the humid inside air can condense and become trapped inside of the insulation during cold winter months. This will likely result in fungal growth (mold) and rot.

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