Eurovent Aktiv vapor barrier membrane is used in residential and industrial construction as a vapor barrier layer that protects the attic against penetration into thermal insulation by excess moisture in the interior of the room. Thanks to the variable Sd value, it gives the possibility to drain moisture from the attic towards thermal insulation, as well as in the case of excess moisture in the insulation drains its excess towards the attic. This intelligent solution used in Eurovent Aktiv prevents, among others the effect of the Foil Bag, i.e. the formation in the attic as a result of excess moisture: fungus in mold, also prevents rotting of structural timber.