Patent ID: 8323770

Claim:
A non-asphaltic roofing underlayment, comprising: a first perforated coated scrim; a second perforated coated scrim; and a non-perforated, breathable and waterproof monolithic or microporous thermoplastic film bonded to and sandwiched between the first and second perforated coated scrims, said thermoplastic film bonded to and sandwiched between the first and second perforated coated scrims via thermal bonding or ultrasonication; wherein each of the first perforated coated scrim and the second perforated coated scrim comprises a material chosen from woven fibers, polyolefins, polyethylene terephthalate (PET); polyamides, polyvinyl chlorides (PVC), polystyrenes, polyacrylics, polypropylene, polyester, fiberglass, cellulose fiber and any copolymers or blends thereof; wherein the breathable thermoplastic film is selected from the group consisting of a polyurethane based thermoplastic film, an ethylene methacrylate copolymer based thermoplastic film, an ethylene acrylic acid based thermoplastic film, a micro-porous polyolefinic film and a micro-porous polyester film; and wherein each of the first perforated coated scrim and the second perforated coated scrim has a thickness of about 6 to about 60 mils, and wherein perforations in the first perforated coated scrim or the second perforated coated scrim or both can be varied in number, size or shape or a combination of any of these so as to allow tailoring of breathability of the non-asphaltic roofing underlayment when applied upon a roof surface.