I have a metal roof with bubble wrap insulation. I am building under this and have a cathedral ceiling with trusses. There is a range of about 8 inches to 30 inches between the roof and ceiling. I have a vented soffet and an eave vent on both gable ends. I am wanting to use corragated tin for the ceiling. What should I do to be sure it won't sweat. I am considering different types of insulation, what would be best? The building is near a creek so it may be damp.