Abstract: A carrier is coated with a suitable adhesive. That surface of the adhesive which is to be placed in contact with the support for the membrane is united with an assembly consisting of a film, and a sheet of material which does not bond to the film. The sheet is impermeable to the hot adhesive, and both film and sheet have perforations which are in substantial alignment. The sheet is positioned on the outside of the assembly, facing toward the support. The adhesive is exposed through the aligned perforations and provides continuity of material throughout the membrane. The imperforated portions of film and sheet can slide relative to each other, thus providing a so-called "limited-slip sheet" for the membrane. Preferably, the impermeable sheet is preperforated, while the perforations in the film are created by the heat of the adhesive, as both film and sheet are applied simultaneously with the coatings of the carrier by the adhesive.

Abstract: This under-roofing material for roofs to be covered with tiles, slates and the like consists of a sheet of agglomerated fibres coated on one face with a layer of bitumen just sufficient for constituting when cooled a micro-perforated structure preventing the passage of liquid by capillarity while permitting the passage or air or vapor, this material having a strength sufficient to withstand the fall of objects or personnel during its use, and being essentially liquid-tight and pervious to air and vapors.