Composite films include a water-impermeable substrate layer composed of plastic having a coating. In such composite films, the hot-melt adhesive can also be activated in a contactless manner from the side of the composite film opposite the hot-melt adhesive layer. In the application of roof membranes, this leads to the advantage that the membrane no longer has to be moved after the activation of the hot-melt adhesive and can be laid in final positions of the membrane even before the activation of the hot-melt adhesive. In addition, by such composite films, the need to activate the hot-melt adhesive by open flames is avoided and thus the hazard potential of the processing is significantly reduced. Further, a method applies corresponding composite films to a substrate wherein the hot-melt adhesive layer is activated and melted by an inductor.
