Home | Chimney Supplies | Chimney Accessories | Sealants, Caulking & Mortars | FlashSeal Sealant 1-Gallon Black

FlashSeal Sealant 1-Gallon Black

FlashSeal Sealant 1-Gallon Black
Free Shipping
SKU DP-24636
Weight 14.00 lbs
UPC 709057740012
MPN 24636


FlashSeal is a versatile and easy to use flashing repair system that, when dry, forms a flexible waterproof membrane. It’s formulated for permanent adhesion to asphalt shingles, metal flashings, brick, and other chimney and roofing materials. Use FlashSeal to solve problem leaks around the base of chimneys, stacks, and vents. It is also great for sealing around skylights.
Repairing flashings that have been tarred over, split, cracked, or are in disrepair is easy with FlashSeal. It’s like installing a custom fit rubber boot at the base of the chimney! It remains permanently flexible and has a 7 year warranty when used with FlashSeal Reinforcement Fabric.
For complete chimney protection, we recommend waterproofing the chimney and sealing the chimney crown.
  • 7 Year Warranty
  • Stops Leaks Around Chimney, Stacks, and Vents
  • Stays Flexible Over Time
  • Available In Black, Brown, and White
  • Easy Brush-on Application
  • Soap And Water Clean-up
Technical Information:
  • Coverage Rate: Approx. 28 linear feet
  • Available Sizes: 1 gal. gallon containers
  • Application Temperatures: Minimum 45° F
  • Application Method: Brush
  • Dry Time: 12 hours of dry, clear weather for proper curing
  • Cleanup: Soap and water while product is still wet


Average customer rating:
(1 reviews)  

1 Most recent customer reviews (see all reviews):
Dec 5, 2016
11/5 stars, this stuff saved me close to 1100 dollars in roofing repair.

So, my situation: My house is nearly 150 years old with a steel roof of indeterminable age. Spoiler alert, it leaks. Particularly bad was the flashing around the chimney, which was "sealed" with sheet steel, mortar, and dreams. It leaked like a sieve. In addition to a few other repairs I needed (rusted out roof bolts, seam leaks where roof meets exterior wall, etc), roofers and chimney specialists quoted me between 1100 and 1800 to stop all the leaks. I asked them what products they'd be using, and they all said "FlashSeal and mesh".

Being the cheapskate, DIY nerd that I am, I googled it. Any moron can apply this stuff. I cleared the old flashing, pressure-washed the contact areas, and painted the stuff on. Done in less than an hour. So then I looked at my remaining 9/10ths of a bucket of Flash Seal, and got a little crazy. I put down FlashSeal, Mesh, and more FlashSeal anywhere that even *looked* like it *might* be the source of a leak. It's been two weeks, and I have not been able to locate a single continued source of leaks.

So far, so good. I will update in a year to see if the stuff has withstood the test of time.

For those curious, the installation goes thusly:

Clear the contact surfaces thoroughly. I used a pressure washer, windex, and a towel.
Apply a generous coat of FlashSeal. Let it get a little sticky.
Apply a layer of FlashSeal reinforcement mesh, covering the gaps you're looking to seal. If it's on an angle, start from the bottom and layer the mesh such that the 'higher' part that overlaps is on top.
Apply a generous coat of FlashSeal on top of the mesh. Keep applying until the mesh is coated into a single, continuous surface without any holes. Wait 45 minutes, repeat.
Keep doing that until you are confident that nothing can get through.