December 15, 2020

Application Guidelines for Installing XL-Perm (STPU) Hybrid Based Air, Vapor, & Water Resistive Barrier Coatings at Various Temperatures

Pecora’s air, vapor, and water resistive barrier system consists of fully engineered and compatible products that work together to provide complete air, vapor, and weather barrier protection for your building envelope. Our products can be used together as a system or independently as needed. The system products include: AVB Silicone Sealant, ProPerm VP Water-Based Fluid Applied Barrier Membrane, XL-Flash STPU Flashing and Joint Filler, XL-Span Preformed Silicone Transition Membrane, XL-Perm ULTRA VP STPU Permeable Fluid Applied Barrier Membrane, and XL-Perm ULTRA NP STPU Non-Permeable Fluid Applied Barrier Membrane.

Our XL-Perm air, vapor, and water resistive, fluid-applied coatings utilize a solvent based hybrid (STPU) formulation which allows the coating to be successfully applied at a variety of temperatures including below freezing (32°F/0°C). We have developed a list of installation guidelines which address roller and spray applications including applying these coatings at low temperatures.

Before we jump right into the installation, the following steps are required prior to the roller or spray application of our XL-Perm coatings:

  • Ensure all surrounding areas are protected from damage during installation of the Pecora XL-Perm coatings.
  • Complete all change of plane, seams, static joints, and flashing with Pecora XL-Flash before applying Pecora XL-Perm coatings. When used as a flashing, apply XL-Flash at 20-40 wet mils.
  • For transitions between building components with significant movement, use Pecora XL-Span transition system.

XL-Perm Coating General Installation Guidelines

  • Pecora XL-Perm coatings may be applied with a roller or approved airless sprayer (refer to Technical Bulletin #210 & Technical Bulletin #211 for equipment requirements and standard operating procedures).
    • Spray apply to exterior wall in a single coat through approved airless spray equipment.
    • Roller apply to exterior wall assembly using vertical strokes with slight diagonal slant.
    • Recommended nap size:
      • Rough surfaces such as CMU = ½” to 5/8” (depending on porosity)
      • Smooth surfaces such as exterior sheathing = ½”
    • Apply coatings at recommended wet mil thickness.
  • Inspect for pinholes, voids or gaps in the membrane and repair as needed.
  • Allow product to cure; these times will vary depending on temperature, substrate, and humidity. At 70°F and 50% humidity, Pecora XL-Perm coatings should be dry to the touch in one (1) hour.

Low Temperature Applications

Our XL-Perm STPU hybrid-based fluid applied coatings, XL-Perm ULTRA VP and XL-Perm ULTRA NP, may be successfully applied at various ambient temperatures ranging from 5°F to 100°F. The following will apply to low temperature applications:

  • Areas to received coating must be clean, dry, and FREE OF FROST or any contaminating substances.
  • Material temperature should be at 65°F or greater. Store coatings in a temperature-controlled area, if possible.
  • Pecora XL-Perm Coatings may be ROLLER APPLIED at ambient temperatures down to 5°F (-18°C). The adjacent graph illustrates the change in product viscosity as temperature decreases.
  • Pecora XL-Perm Coatings me also be SPRAY APPLIED at low temperatures provided the material conditioning and equipment requirements published in Technical Bulletin #210.
  • Low temperatures and relative humidity will reduce the cure rate of moisture cure, fluid-applied coatings. The Pecora XL-Perm hybrid (STPU) formulations are less sensitive to low temperature/relative humidity and will continue to cure at these conditions. See table below for skin times and cure rates at low temperature/relative humidity.


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