Prosoco FastFlash is designed to prevent the unwanted movement of water and air through building envelopes. You can use R Guard FastFlash as a liquid flashing membrane in rough openings and to counterflash waterproofing and air barrier components in new or existing wall assemblies. R Guard FastFlash is a gun-grade, waterproofing adhesive and detailing compound that combines the best of both silicone and polyurethane properties. This single-component, 99% solids, SilylTerminated-Poly-Ether (STPE) is very easy to gun, spread and tool to produce a highly durable, seamless, elastomeric flashing membrane. You can 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 counterflash through-wall sheet flashing. R Guard FastFlash is suitable for all climates, bonds directly to damp or dry surfaces and cures under a host of weather conditions. R Guard FastFlash 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. R Guard FstFlash is solvent-free and isocyanate free and complies with all VOC regulations. Silane functional polymer provides superior long-term adhesion, crack bridging and weathering characteristics. FastFlash 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. R Guard FastFlash will not tear or lose effectiveness when exposed to weather during construction. R Guard FastFlash may be exposed to weather for up to 6 months without compromising performance. It's single component formulation saves you time and does not require mixing. R Guard FastFlash is quite easy to gun and spread in all climates. R Guard FastFlash produces an opaque membrane when installed at the recommended 12–15 wet mils to simplify inspection and quality control. R Guard FastFlash bonds and cures in wet weather and on damp substrates.
For vertical or horizontal above-grade applications to:
most other building materials
Not for use as a structural sealant.
Not for use in place of appropriate through-wall flashing.
Not for use below grade or in locations designed to be continuously immersed in water.
30 minutes (at 70°F (21°C) and 50% relative humidity)
4 hours (at 70°F (21°C) and 50% relative humidity)
Hardness Shore A
3/16" thickness/24 hours
Elongation at break
Application temperature range
35°F to w 110°F
30 g/L maximum
Usable life and storage
12 months in unopened, factory-sealed container
Always test a small area of each surface to confirm suitability and desired results before starting overall application. Test with the same equipment, recommended surface preparation and application procedures planned for general application.