Hello, so I lease an office/warehouse space and I am in the first unit so I have 3 exterior walls.  It’s 27’x 60′ and all along the 60′ wall where the ceiling meets the wall, the builder left the parapet open to the conditioned space.   It’s a balloon-framed parapet wall…   I can see up into the parapet and the inner wall above the ceiling was not insulated at all, just sheet metal.   So in the winter, the warm air rises up into the parapet then condensation forms causing major problems.  How do I seal the parapet off at the base? Is there some kind of self adhesive membrane that I can go from the ceiling across an 8″ gap to the wall to seal it off or?