Abstract: A built-up roof structure includes an insulating layer of expanded, foamed, closed cell, polystyrene insulation panels covering an entire roof. A water impermeable membrane is laid loosely over all of the insulation panels, and a protective layer of extruded, foamed, closed cell, polystyrene protection panels is installed over the membrane to have fissures between each protection panel to allow rain water to run down to the upper face of the membrane. Downwardly open channels are provided in the bottom of each of the protection panels to facilitate runoff.

Abstract: In a house structure in which insulated material is placed between and over attic floor joists, an insulation vent provides an air channel to allow free flow of ventilating air along the underside of roof sheathing between the exterior soffit and the interior of the attic above the insulating material. The vent is molded of one piece of expanded polystyrene. The vent has a base with longitudinal ribs, a pair of walls extending upward at an angle, and a pair of flanges extending outward from the edge of the wall, for attachment to the roof joists. The cross section of the vent is generally U-shaped. The vent is installed by flexing the walls inward, inserting the vent between a pair of roof joists and against the roof sheathing, and releasing the walls. The walls expand, pushing the flanges against a pair of roof joists. Friction holds the vent in place. The center of the U forms a channel for the passage of air.

Abstract: An insulation material having relatively high moisture permeability, includes an inner sheet of expanded polystyrene of substantial thickness. Attached to the polystyrene is an impermeable kraft supported aluminum foil outer layer having the paper side facing the polystyrene. An adhesive layer is provided to join the outer layer to the inner layer. Finally, a plurality of moisture permeation creating perforations are intruded through the outer layer and the adhesive layer and extend into the inner layer to render the outer layer and adhesive layer moisture permeable. The perforations are formed by bonding the layers with the adhesive, allowing the adhesive to set and thereafter passing the bonded layers against a means for forming perforations.