Quote Originally Posted by ordjen View Post
The problem being encountered here is not interior generated moisture, but moisture that is being driven through the exterior walls where it encounters a cold, impermeable air barrier on the inside. Here it condensates. This type of problem did not exist before the advent of air-conditioned homes and the use of absolute air barriers such as plastic. Those interior walls must let the moisture continue on through. Similarly, wall papers with plastic coatings or metalic finishes should not be used on exterior wall surfaces as they also form impermeable barriers.

In hot humid climates, if a vapor barrier is to be used at all, it should be on the exterior side of the wall, the opposite of in Northern climates. An absolute vapor barrier such as sheet plastic should not be used at all in either climate. My house here in Portland ,Oregon does have such a plastic barrier in back of the drywall. However, the air in Portland in summer is very low in humidity. Also, air-conditioning is not used here as much as in other parts of the country, so condensation inside the wall is not a problem.
Using a vapor barrier on the outside is not a good idea except in a very few areas in this country. See my first response to this thread.


I don't want to rewrite the whole post, but you can use the references to determine if the climate in your area would call for an exterior vapor barrier. Not many places in this country would have a dew point above room temperature, and if they did, it would be for only a few days each year.

I think you are right about just not using any vapor barrier in Florida. The dehumidifier should take care of the problems with condensation.