A vapor barrier as you described will cause condensation on/in the
drywall.  If you use bathroom grade (blue) drywall and it is properly
taped you do not need a vapor barrier as the drywall serves as such.

On Thu, 7 Sep 1995, Michael Knies wrote:

>         We are in the process of renovating an old department store to serve
> as a new museum.  It is an 80,000 sq. ft. building and it will be multi-tenant
.
> We will occupy about 15,000 sq. ft. on the third and fourth floors. There will
> be about 11,500 on the thid floor and 3,500 on the fourth floor (to be
> developed in the future). There will be a 30'x16' cut-out between the floors
> to be sealed until fourth floor development.  There will be a rubber roof.
>         The exterior walls are brick (three courses thick I think).  The
> architects plan to attach metal studs to the brick walls, place rigid foam
> insulation between the studs and screw drywall onto the studs.
>         We would like to place a vapor barrier behind the drywall to help
> retain winter humidification in our space.  I'm looking for suggestions
> concerning options for vapor barriers, keeping in mind that the barrier will b
e
> punctured by screws and that we are on a very tight budget.
>         Thanks. Post to me directly unless you think the list will be amused
> by talk about neoprene, etc.
>
> Michael Knies
> Collections Manager/Archivist
> Canal Museum, Easton PA
> [log in to unmask]
>