Areas of application, Vapour check (alternate terms: vapour control or retarder) membrane for use on the inside of insulation installed between rafters or wall framework, in combination with fibrous insulation mats and boards. Can be installed directly on top of sheathing for use underneath exterior insulation, also in combination with blown-in insulation materials. This membrane can be permanently exposed to diffuse UV light – e.g. in areas without inner cladding. In the case of refurbishment from the outside and installation between two layers of insulation, the choice of insulation materials for the two layers is limited to mineral or rock wool. The thickness of the external mineral wool insulation needs to be calculated on a project-specific basis; please contact Technical Support at pro clima in Germany for assistance. This membrane can be used on building components that are diffusion-open to the outside or are diffusion-tight, e.g. pitched, flat or green roofs, after appropriate design calculations have been carried out.