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Self-adhering vapor permeable air barrier membrane

38-3/8" X 141' Roll

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Availability: In stock



GCP Applied Technologies (Formerly Grace) Perm-A-Barrier® VPS (Vapor Permeable Sheet) is a vapor permeable air barrier membrane consisting of a proprietary breathable carrier film with a specially designed adhesive.

This product provides superior protection against the damaging efects of air and water ingress on building structures. It creates a solid barrier against air infiltration and exfiltration, which minimizes associated energy loss and condensation problems.

Perm-A-Barrier VPS membrane is vapor permeable for wall assemblies requiring this “breathable” characteristic. As a vapor permeable membrane, it permits the difusion of water vapor that may otherwise condense in the wall structure; but is impermeable to liquid water, which allows the material to act as a water drainage plain.


  • Fire Resistant—meets NFPA 285 as part of various wall assemblies •Air tight—protects against air passage and associated energy loss
  • Vapor permeable—“breathable” membrane prevents moisture from being trapped in the wall cavity by allowing walls the ability to dry
  • Water resistant—resists hydrostatic water pressure and wind driven rain
  • Self-adhered—eliminates the need for mechanical fasteners
  • Controlled thickness—factory made sheet ensures constant, non-variable site application
  • Lightweight—allows for easy handling and installation
  • Flexible—accommodates minor settlement and shrinkage movement; bridges crack and joints in substrate
  • Strong adhesion—to prepared construction substrates such as plywood, oriented strand board (OSB) block, masonry and exterior gypsum boards
  • Compatible with GCP Perm-A-Barrier® FlashingSystems

Principal Applications
Vapor permeable air barrier for new and remedial commercial and residential applications. Perm-A-Barrier VPS membrane is installed onto exterior wall substrates and behind the exterior cladding.

System Components

  • Perm-A-Barrier® VPS — for use on above-grade walls at installation temperatures above 20°F (-6°C)
  • Perm-A-Barrier® Primer Plus — Water-based vapor permeable primer used to facilitate tenacious adhesion of Perm-A-Barrier VPS to the substrate. For use at temperatures between 40°F and 120°F
  • Perm-A-Barrier® Adhesive — Low temperature vapor permeable primer used to facilitate tenacious adhesion of Perm-A-Barrier VPS to the substrate at temperatures as low as 20°F (-7°C)
  • Perm-A-Barrier® Wall Flashing — heavy duty, fully-adhered membrane for throughwall flashing detailing
  • Perm-A-Barrier® Detail Membrane — flexible, fully-adhered membrane for detail flashing areas
  • Bituthene® Liquid Membrane — two-component, elastomeric liquid applied detailing compound used for details and terminations
  • Bituthene® Mastic — rubberized asphalt-based mastic used for details and terminations
  • Sealants — refer to Technical Letter 1 for details on compatible waterproofing sealants

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