Apparently, there are no materials that are both compressible and have zero water vapor permeability. I recently came across an application that requires such a solution. To address the problem, I devised an approach that combines a deformable gasket (round – orange) and a flexible vapor barrier film (thin – light blue) like aluminum foil. The foil prevents vapor migration, while the gasket provides compressibility. Since the foil is flexible, it can conform as the gasket changes shape.