Insulation and plastic barrier?

Old 01-13-19, 06:47 AM
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Insulation and plastic barrier?

I have a new build addition and putting faced insulation in the walls. Should I also put plastic vapor barrier over the insulation for extra draft protection? Sometimes you get those little draft leaks coming through the top and bottom sill plates, thought maybe with the plastic it would help keep some of it out, I live in a cold high wind area.
Old 01-13-19, 07:10 AM
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There is so much discussion, some conflicting, some personal, regarding vapor barriers (barriers and retarders) that you will find.

A barrier (plastic) does not allow anything to pass and that can cause issues unless the house is specifically designed to handle the excess moisture that will be generated.

Personally, if you have an exterior wrap (tyvek). have addressed all the openings (air infiltration) and proper insulation (with kraft paper) I would never install plastic!.
Old 01-13-19, 09:26 PM
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The paper is somewhat of a vapor barrier and general thought is not to use two, as that can trap moisture. Air sealing, prior to insulating, unfortunately, was probably what you should have done to the walls.

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