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Spray Applied Air and Vapor Barrier

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Product Data Sheet


Perm-A-Barrier Liquid is a two component, synthetic rubber, cold-vulcanized, fluid applied membrane. It cures to form a resilient, monolithic, fully bonded elastomeric sheet. 

Perm-A-Barrier Liquid will protect above grade wall assemblies against the damaging effects of air, vapor and water ingress. Perm-A-Barrier Liquid also provides an effective barrier against air infiltration and exfiltration and associated energy loss and condensation problems.

The Volatile Organic Compound (VOC) content of Perm-A-Barrier Liquid is less than 75 g/L. 


  • Air tight—exceeds CCMC requirements for air barrier membranes and complies with Massachusetts State Energy Code and meets new ASTM E2357 standard
  • Fully bonded—transmits wind loads directly to the substrate
  • Elastomeric—accommodates minor structural movements and will bridge cracks
  • Asphalt free formulation—does not become brittle with age and remains flexible to -23°F (-30°C)
  • Chemical cure—no loss of volume; wet thickness is equal to dry thickness
  • Seamless—continuous membrane integrity with no laps
  • Primerless—applied directly to the substrate with minimal surface preparation
  • Damp surface tolerant—can be applied to damp-to-touch surfaces
  • Solvent free
  • Cold applied—eliminates fire hazards during application
  • Quick and easy application—by airless spray
  • Wide application window—can be sprayed down to 20°F (-7°C)
  • Versatile—easy to use at details such as internal and external corners, brick ties, penetrations, etc.
  • Enhanced weatherability—product can be exposed to UV up to a maximum of 60 days 

Principal Applications

New and remedial air and vapor barriers for commercial and residential applications:

  • Concrete block walls with brick veneer or preformed cladding panels
  • Steel or wood stud walls with exterior gypsum board, brick veneer or pre-formed panels
  • Do not specify Perm-A-Barrier Liquid for interior applications. 

System Components

  • Perm-A-Barrier Liquid—for horizontal and vertical applications
  • Grace S100 Sealant—one part neutral curing, ultra low modulus silicone sealant for detailing and joint treatments.
  • Bituthene Liquid Membrane—for details and terminations
  • Perm-A-Barrier Wall Flashing—heavy duty fully-adhered membrane for through-wall flashing details
  • Perm-A-Barrier Detail Membrane—flexible fully-adhered membrane for flashing around window jambs, door jambs and sills.
  • Perm-A-Barrier Aluminum Flashing— flexible, aluminum faced, fully-adhered membrane for detail flashing areas 

Where should Perm-A-Barrier Liquid be used?
Perm-A-Barrier Liquid is intended for use as an above-grade air and vapor barrier.

Can Perm-A-Barrier Liquid be applied to green or damp concrete?
Perm-A-Barrier Liquid Air & Vapor Barrier waterproofing membrane may be applied onto "green" concrete or over damp substrates. Remove any visible water prior to application. Once applied, Perm-A-Barrier Liquid membrane will not be affected by light rain showers.

Is Perm-A-Barrier Liquid compatible with spray applied polyurethane foam insulation?
Spray polyurethane foam insulation is compatible with Perm-A-Barrier Liquid membranes. It will adhere to Perm-A-Barrier Liquid when used as an exterior insulation in air and vapor barrier applications. Perm-A-Barrier Liquid membranes adhere well to cured polyurethane foam insulation.

How is Perm-A-Barrier membrane applied?
Perm-A-Barrier is a spray application material.

How long can Perm-A-Barrier Liquid be exposed to sunlight?
Perm-A-Barrier Liquid should be covered within 60 days after installation.

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