vapor barrier?

[Sylvain_tp]

Hi all,
the ceiling of my house is in stucco and I would like to cover up with a new drywall. Presently the ceiling is made with stucco, drywall, vapor barrier and insulation. The question is: Do I have to put a 2nd vapor barrier between the new drywall and the old stucco or just put the drywall again the stucco.
Thanks,

[Rich]

Just drywall against the stucco.

[danh]

Rule of thumb:
If you ever put two vapor barriers in, there must be a way for the moisture to get out from between them. Otherwise moisture that gets between will never be able to dry out.

For example:
1. Installing a 1-inch layer of sprayed-in rigid foam plastic insulation in a wall cavity, then batt, then a vapor barrier ensures doesn't work: any moisture (pipe leak, roof leak) that gets into the wall cavity is trapped there, with nothing to do but rot wood & grow mold.

2. Constructing a vented attic with a foil-faced radiant barrier roof decking with the foil facing inward in combination with a both a vapor barrier & batt insulation on the floor of an attic DOES work. The entire attic is between vapor barriers, and moisture that gets into this space is vented.

Um yeah, stay away from double VDR systems.