Go to The Journal of Light Construction and enter vapor barrier in
their search engine
You will get more intelligent and consistent answers here than
most places. The issue will be whether your code enforcement will
allow you to put it where you want. Many places use national
energy guidelines which may ignore your high humidity, more
cooling days than heating days condition.
This article speaks most directly to your area and your problems:
Here is a partial quote:
Contrary to code, do not use a vapor diffusion retarder on the
interior of the wall system, because walls in the hot, humid South
dry to the inside, not to the outside. Especially avoid placing a
sheet of poly under the gypboard, or covering the gypboard with
vinyl wall-paper. The only place where we use poly is on the
interior side of walls around tub and shower enclosures that do
not abut an outside wall. In these localized areas, we feel its
prudent to protect the partition wall cavity from the high
humidity generated in the bathroom.
Keep the whole world singing. . . .
If you are going to use a vapor barrier, it belongs on the warm side of
the insulation. If you expect to be cooling your house more often than
you expect to be heating it, put the vapor barrier on the outside.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.