Prosoco FastFlash

FastFlash is a liquid flashing membrane available in gun or roller grade. Use FastFlash in rough openings, to fill joints and seams, to counter-flash waterproofing and air barrier components in new or existing wall assemblies, and to seal around penetrations. Use FastFlash independently or with compatible R-Guard products to prevent the unwanted movement of water and air through building envelopes.

FastFlash | High-Performance Liquid Flashing Membrane

FastFlash is a versatile liquid flashing membrane designed for use on rough openings, transitions, and seams in new or existing wall assemblies. This gun- or roller-grade solution creates a seamless, durable barrier against water and air intrusion, effectively protecting building envelopes. Engineered by PROSOCO, FastFlash is ideal for waterproofing projects in commercial and residential construction and is a key component in the R-Guard air and water barrier system.

Product Description

Formulated as a red, viscous paste, FastFlash cures to a durable elastomeric seal that is compatible with most building materials. It fills small cracks, counter-flashes joints, and can be used around penetrations to eliminate water entry points. With a VOC content of only 30 g/L, it meets sustainability benchmarks while delivering performance that exceeds industry standards. Its high solids content and wide temperature tolerance ensure it remains reliable in varied environmental conditions.

Key Benefits of FastFlash

  • Forms a seamless, fully adhered waterproofing layer
  • Compatible with R-Guard air and water barrier systems
  • Primerless adhesion to most common construction surfaces
  • Quick and easy application with gun or roller
  • Highly flexible and durable once cured
  • Passes key sustainability standards, including Red List Free, Declare, and VOC Compliance

Common Applications

  • Rough openings in windows, doors, and curtain walls
  • Transitions between dissimilar materials
  • Sealing cracks, seams, and penetrations
  • New construction and retrofit waterproofing projects

Storage & Packaging

FastFlash is available in 29-oz tubes, 20-oz sausages, and 2-gallon roller-grade containers. Store unopened in a cool, dry place for up to one year. Protect from freezing temperatures.

Product Properties

Property Value
Shelf Life 1 year in tightly sealed, unopened container
VOC Content 30 g/L maximum
Form Viscous paste, mild odor, red color
Flash Point >200 °F (93 °C)
Total Solids 99%
Coverage Rate 22–28 sq ft per 29 oz tube, 15–17 sq ft per 20 oz sausage, 50–100 sq ft per gallon
WT/GAL 11.75 – 12.5 lbs
Available Sizes 29-oz tube, 20-oz sausage, 2-gal (roller-grade)

Looking for a companion product for detailed joints and seams? Check out the Joint & Seam Filler Sealant. Learn more about FastFlash at PROSOCO.