Roxul in the attic-vapor barrier?
mike7811
| Posted in General Questions on
I’m thinking of replacing the old fiberglass insulation in my attic. I’d like to use roxul but was wondering about the vapor barrier. Can I simply remove the old insulation and lay the vapor barrier over the ceiling joist and friction fit the roxul over the plastic? What thickness vapor barrier should I use? I live in zone 6A.
Thanks!
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Replies
Mike,
Building codes do not require, and building scientists do not recommend, a vapor barrier in this location. All you need is a vapor retarder -- and a few coats of ordinary latex paint is usually enough.
In all cases, your ceiling needs to be as airtight as possible. In other words, an air barrier is more important here than a vapor barrier.
For more information on this topic, see:
Vapor Retarders and Vapor Barriers
Forget Vapor Diffusion — Stop the Air Leaks!
Do I Need a Vapor Retarder?