1035 Secure Start® Permeable underlayment is a breathable, synthetic membrane designed to both prevent water from penetrating a roof and help release trapped moisture from poor attic ventilation. It is lightweight despite three durable layers, the middle a monolithic membrane that provides vapor permeability. Secure Start® Permeable is suitable for use as a water-shedding underlayment or dry-in sheet in steep slope roofing applications with asphalt shingles, wood shakes/shingles, metal, and mechanically-fastened roof tiles. Secure Start® Permeable is approved for use under fire-rated, code-compliant roof coverings.