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INSTALLS FAST
Forget peel-and-stick if you don’t want to waste time and money. Fluid-applied FastFlash installs 34% faster than traditional peel-and-sticks.
BONDS TO DAMP SURFACES
Take rain out of the equation and circumvent project timeline delays. FastFlash can be applied to damp substrates and rained on immediately -- making rain a non-issue when it comes to your construction schedule.
DUMMY-PROOF
Irregular, complicated transitions are no problem for fluid-applied FastFlash, which easily covers all kinds of details that are extremely difficult and cumbersome with peel-and-stick, sheet goods or fabric-reinforced products. FastFlash always fits.
HIGH-PERFORMING
Make your energy goals a reality. FastFlash performs to such a high standard that they are continuously selected for some of the world’s most high-performing, energy-efficient buildings.
PROVEN & TRUSTED
FastFlash is the *only* fluid-applied flashing material on the market that’s been independently proven to perform for 10+ years. It's trusted by professionals and homeowners alike.
PROMOTES COMFORT & HEALTH
FastFlash is VOC-compliant, solvent-free, isocyanate-free and phthalate-free, giving it the green light for use on the most stringent environmental projects on the planet.
Mad-Gunner
2025-09-05 10:58:26
Prosoco R-Guard Fast Flash (and related Joint & Seam Filler) works as described to seal the gaps between different building materials. Tape and caulk products aren't all-purpose as liquid flashing products, where you apply a large bead in bulk, and then spread as needed for the situation. Corners, odd shapes, vertical, horizontal, works equally well inside tight spaces as it does across large flat areas. You can push the liquid flashing into cracks in the same way that caulk is applied, plus you spread it out with a plastic fin or other spreader tool. Cleans up easy with paper towels before it dries. The finished product is a rubberish mastic that provides a permanent barrier to water, air and insects.Cure (drying) time is dependent on humidity. If you're working in a very dry environment (e.g. below 50% humidity), a small amount of water misting with a spray bottle will speed things up. I'm in central Texas and find most days that I can spread the joint and seam filler in the morning, and then after lunch apply the fast flash. On especially dry days (humidity below 30%), I'll very lightly mist the substrate before applying the joint and seam filler. A great benefit, rain isn't a worry - you can apply these products and not worry about rain later in the day!The joint and seam filler is pink and reinforced with fibers, designed to fill large gaps between material, goes on very thick and the finished surface isn't as smooth/flat in comparison to the fast flash.Fast flash can be used by itself, or on top of the joint and seam filler. Dark red in color, nearly the same product as the joint and seam filler, but less fiber reinforcement to allow being applied as a thin top-coat that finishes smooth and sexy!Applied successfully at the foundation between concrete and base angle (e.g. sill plate) for metal buildings, workshops, and barndominiums. Works great for commercial and residential construction across a wide variety of materials!
Michael Neumann
2025-07-05 14:27:21
It's not cheap, but it does a great job. It dries to a hard rubber consistency which worked really well to flash the tar paper around our windows. We flashed the rough opening first, to seal the tar paper to the OSB, and then flashed a second time after installing the window itself.
Daddy D
2025-07-04 13:12:44
Bond will last a lifetime.Probably the best product on the marketWill tolerate weather changes and most movement if applied thick enough.Is not low costRequires appropriate sized gunDifficult clean up.Once cured, it will take great effort to remove from any surface (not even a power washer will work)Red color not aesthetically pleasing for exposed work.
Ed
2025-07-03 15:36:34
This stuff is amazing. Great grip, easily seals even big gaps for a smooth waterproof seal. Used on window rough openings, but will work anywhere you need waterproofing
Flyway
2025-06-10 18:28:28
Phenomenal product, sticks to everything, maintains its pliable rubbery qualities. Can’t imagine flashing an opening any other way. Air and water tight. Window flashing tape sticks like glue.It’s messy and sticky, if that’s a con it’s the only one I found.
Rubyshield
2025-04-25 18:30:08
Great product. I would buy more from Amazon if shipping wasn’t so long. Otherwise, I get it from Small Planet.
Brent Duncan
2025-03-06 14:27:25
Works, but a little spendy. Need to sell a 2, 3, 4 pack for cheaper or something
Sam B
2025-01-31 12:32:44
I used this to seal the transition between OSB sheathing and sill plates that are sitting on concrete. It was easy enough to apply, although more liquid than expected. Once cured, it felt like rubber and it gives me confidence that it's a great seal. It took two sausages to cover 40 feet of sill plate.
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