Expert: Dave Johnson - 1/3/2009

Question
I'm renovating our master bath, and on a home show or somewhere I thought I saw someone putting a plastic vapor barrier in addition to standard paperfaced between-stud insulation.  

I've done a little web-searching, and am not finding any reference to doing both.  Is my memory faulty, or does doing both plastic and paperfaced have any advantage?  Or, on the other hand, does putting TWO "vapor barriers" create moisture problems.

THANKS!

Answer
Hi Brian,
In a bathroom, you could run into moisture problems with two vapor barriers.
If the walls are going to be open anyway and you live in a colder climate, I'd use 2" foam between the studs sealed with spray foam and cover the studs with 1/2" foil faced foam and moisture resistant drywall over that.

If this isn't clear, please mail me again,
Best of luck,
Dave