thats why i mentioned the rubber,make shit simple,to much thinking for something so simple,i have no doubt the spray in foam will do the job,but the cost factor,now this is gonna be a finished home when done take that in account ,so do it once,spray foam plastic vapor barrier over it and sheet rock ,done ,if you loved in a fantasy world were shit didnt happen,just fans in there would keep condensation down,but you got mountains hills to deal wit also,shit were im at most of what is called winter is the only time we have humidity ,just dry as hell all year,like breathing fire all the time hahahah