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R-Guard Fast Flash

RG Fast Flash
2.00 LBS
  • Product Description

    The Architectural Record recognized R-Guard FastFlash and Cat 5 air/water barrier in the category of "Top Waterpoofing Products of 2010".


    FastFlash is part of the family of PROSOCO R-GUARD® products developed to prevent the unwanted movement of water and air through building envelopes. Utilize FastFlash as a liquid flashing membrane in rough openings and to counterflash waterproofing and air barrier components in new or existing wall assemblies.

    Prosoco R-Guard FastFlash is a gun-grade waterproofing, adhesive and detailing compound that combines the best of silicone and polyurethane properties. This single-component, 99% solids, Silyl-Terminated-Poly-Ether (STPE) is easy to gun, spread and tool to produce a highly durable, seamless, elastomeric flashing membrane.

    Use FastFlash as a liquid flashing membrane in rough openings of structural walls. Allows same day installation of windows, doors and other wall assembly, waterproofing or air barrier components. Use FastFlash to adhere, transition and counter-flash through-wall sheet flashing. Suitable for all climates, FastFlash bonds directly to damp or dry surfaces and cures under a variety of weather conditions. It simplifies the process of producing watertight details in new or existing construction.

    Use FastFlash as part of a continuous, building-wide air barrier system, or to complement conventional waterproofing or air barrier components.

    Appropriate for vertical or horizontal, above-grade applications to concrete, masonry, natural stone, structural sheathing, architectural metals, painted metals, glass, PVC, FRP, EPDM and most other building materials. Covers 15-20 square feet per sausage.


    • Solvent-free, isocyanate-free. Complies with all VOC regulations.
    • Silane functional polymer provides superior long-term adhesion, crack bridging and weathering characteristics.
    • Bonds to most common building materials without priming to produce a durable, structural, weather-tight seal which is not subject to tearing or displacement when subjected to wind loads during construction.
    • Will not tear or lose effectiveness when exposed to weather during construction.
    • May be exposed to weather for up to 6 months without compromising performance.
    • Single component formulation saves time and requires no mixing.
    • Easy to gun and spread in all climates.
    • Produces an opaque membrane when installed at the recommended 12-15 wet mils to simplify inspection and quality control.
    • Bonds and cures in wet weather and on damp substrates.
    • Paintable with most paints after 2 hours.
    • Compatible with most urethane, silicone, and acrylic sealants and coatings.
    • No shrinkage. No staining. No yellowing. 
    • Breathable - allows damp surface to dry.
    • Will not support mold growth.
    • Cured service temperatures: -75 degrees F to 400 degrees F.
    • Meets IITS-0230C and ASTM-C-920.

    . Load up the Fast Flash suasage bag into the Siga Pistol for Tubular Bags to apply and use R-Guard Fast Flash Spreader to sread into a thin layer.

    For a more detailed description, videos, and images please visit PROSOCO's page:

    R-Guard Fast Flash

  • Product Reviews


    Write A Review

    1. Good flashing material with a few application caveats

      After seeing Hammer and Hand use FastFlash for their Passive House projects I decided to I'd try it on my own project. The material itself is pretty amazing. Its mechanical properties are similar to automotive RTV silicone; high modulus of elasticity, thick, very sticky, difficult to remove once cured. The biggest difference between FastFlash and RTV silicone is vapor permeability. If applied to a damp substrate the material will transport moisture to the surface where it will actually bead.

      For application, a Bondo-type spreader was found to be most effective. Since FastFlash is quite thick a fair amount of force is required to achieve desired application thickness. This is especially true when working around 35 fahrenheit which is the low temperature limit of the material. At the end of a day applying FastFlash the tendency is to ease up which winds up wasting a fair amount of very expensive material.

      While FastFlash can be applied to damp substrates I found that it cannot be successfully applied to wet substrates. To me the difference between damp and wet is the ability to see a sheen of water on the substrate surface. If the surface is wet FastFlash appears to skin over before it has a chance to stick to the substrate. It won't stick to the substrate but it will stick to anything else that's not wet like your hands etc.

      If it does stick and cure FastFlash is very difficult to remove. I tried a Stego Wrap / FastFlash detail I later had to take apart. Polyolefins are notoriously difficult to adhere to. FastFlash did not have a problem sticking polyolefin to itself. I ended up tearing the Stego Wrap before the bond between two pieces came apart.

      Overall FastFlash is an amazing flashing material. If forced to build in a cold location or one that's particularly wet the low temperature limit of 35 degrees and skinning behavior when applied to wet substrates are drawbacks that will slow construction.
      on 16th Jan 2014

  • Product Videos

    • Installing the FastFlash System

    Installing the FastFlash System