Prosoco R-Guard FastFlash Liquid Flashing Membrane 20 oz. Sausage

Prosoco R-Guard FastFlash is a single-component, rapid-curing liquid flashing membrane designed to seal transitions, penetrations and rough openings in weather-resistive barriers. Formulated for high adhesion to common substrates—such as CMU, concrete, metal, brick and gypsum sheathing—FastFlash creates a durable, rubber-like waterproof seal that remains vapor-permeable while blocking air and moisture intrusion.

Ideal for both new construction and retrofit applications, this STPE (Silyl-Terminated Polyether) membrane offers exceptional elongation, crack-bridging performance and resistance to UV exposure. Its sausage-style packaging is perfect for use with standard caulking guns, enabling precise application around windows, doors, pipes and control joints.

Key Features

• Single-component, fast-curing liquid flashing
• Forms a tough, rubber-like, waterproof seal
• High elongation and crack-bridging capability
• Vapor-permeable yet air* and watertight
• Bonds to masonry, concrete, metal, gypsum and more
• Easy application with standard 20 oz. sausage caulking guns
• UV-stable for temporary outdoor exposure