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Vapor retarders on insulation batts

Joe Norm | Posted in General Questions on

There are a lot of different kinds of insulation batts sold.

Some have kraft face, others are fully encased in plastic, and some are without any facing on either side.

Most batt jobs I see done by insulation companies are of the bare variety.

All the ones sold at my local lumber yard are either plastic encased or have the kraft paper.

Can someone explain when/where you’d use all these various types of batts.

Thanks

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Replies

  1. Expert Member
    Michael Maines | | #1

    Joe, batts of all types are hard to install properly, without gaps, so it's better to chose a blown-in insulation when possible. But if you decide to go with batts:

    Kraft facing is a vapor retarder, and in some cases makes installation easier. But it also makes it easy to miss gaps between insulation and framing. The facing should generally face the warm side of the assembly.

    Unfaced batts are fine in most cases, as long as there is another, properly located vapor retarder in the assembly.

    Plastic-wrapped batts are strictly for comfort of installation. Newer formulations of non-wrapped batts are not as itchy as they used to be, so I don't see the need for plastic-wrapped batts. But then again, I don't often install batts of any type.

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