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Vapor barrier paint over drywall with poly under it? overkill or will it trap moisture?
Vapor barrier paint over drywall with poly under it? overkill or will it trap moisture? (post #187206)
1) Four mil polythene was installed as a vapor barrier on the inside face of the exterior walls of a new construction house on the water near Seattle WA, per inspectors advice rather than using a vapor barrier paint. (drywall, poly, 2x6 studs, unfaced fiberglass batts, plywood, tar paper , and hardiboard lap siding). The drywall is now on and the installer is suggesting spraying it out with a vapor barrier paint (for 400 more dollars) rather than use the standard primer. Does this create a double moisture barrier with attendant problems or is it a good idea or just a waste of money?
2) Ten years ago I was required to use polythene in the houses I built in Portland, Oregon, but have been unable to find out if vapor barrier paint is a superior solution for this climatic area. Using paint in place of the polythene would allow greater permeability - is this a good thing with the previously mentioned wall construction?
Thanks for your input .