is a double vapor barrier on a South Florida roof bad?

Arthur Moore
Updated: April 9, 2020

I am building a new home in Naples Florida with a metal roof and open cell foam sprayed on underside of roof deck.

I am considering a peal and stick membrane under roof panels but have been advised I would be creating a 'double vapor barrier' potentially trapping moisture in the roof deck causing long term issues given Naples is hot and humid.

I was of impression open cell foam is an air barrier but not a vapor barrier, would the moisture only travel one way?

I have read one option is to a/c the attic space, another is to install the 'peel and stick' over old fashioned roof felt which seems like putting the new modern material over old technology material.

I am owner builder and will be installing roof myself, but spray foam of course by professionals.

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