A novel and flexible test setup to measure the vapour diffusion resistance of building materials and wall components

A novel test setup and procedure to measure the vapour diffusion resistance of building materials and components are presented. In this test setup, a vapour flux across the test sample is induced by cooling down one of the sample’s surfaces by a cooling plate. The cooling plate also acts as a vapour tight plane and hence condensation is created. The vapour diffusion resistance is, via a Glaser-based calculation, inferred from the mass of condensation. Benefits of the novel procedure are its applicability to building components such as masonry, CLT, etc., and its larger flexibility in respect to the boundary conditions. The non-isothermal approach allows the induction of a large (and thus measurable) vapour flux while a quasi-constant relative humidity across the sample can be imposed. In the paper, the novel method is validated based on a bituminous impregnated fibreboard with known diffusion resistance. Thereafter, the method is applied to a masonry wall, showing the importance of diffusion measurements on the component level