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Community and Q&A

Adhering Tape to Liquid-Applied Flashing

finePNW | Posted in General Questions on

Anyone have experience sticking 3m 8067 tape (or any kind of flashing tape) to Prosoco’s FastFlash? I have flashed a window buck with FastFlash and am hoping to tape over the window nailing flanges from flange -> over FastFlashed buck -> Tyvek Commercial D wrap to unify the system.

Edit: to be clear, my question is about sticking it to already-cured FastFlash, not wet-setting it in “liquid” FastFlash! My mistake on the wording there.

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  1. finePNW | | #1


  2. Ryan_SLC | | #2

    One thing, you could try it.

    I think the reverse is typically the issue as the tape is slick and stuff doesn't stick? Liquid flashing by application troweling isn't very smooth. I don't have the answer, happy to bump because I'm interested too. I would bet the answer is Yes it will stick.

    I have read ask the manufactures for a letter, but having done so with multiple wraps and different liquid flashing, not one company has said yes to another company's product sticking--or responded at all. Benjamin Obdyke has been the best with "should work, but test in the field first."

    1. finePNW | | #4

      I appreciate your input! I've had the same experience with manufacturer's taking an understandably very hands-off approach to discussing interaction/compatibility with other company's systems or products. Some one did some backyard testing in 2018, and it appears that 3m actually doesn't stick terribly well to FastFlash, whomp whomp.

  3. Patrick_OSullivan | | #3

    Zip Liquid Flash is widely believed to be a black colored version of FastFlash. Huber does not recommend trying to tape onto FastFlash.

    Here's their document on this topic:

    1. finePNW | | #6

      Thanks kindly for this.

  4. Gnoll | | #5

    How long it is exposed to dust and pollen is a major issue, the gummy finish of stpe will collect dust. 8067 will "stick", but likely not seal air/water if the fastflash is not fresh and super smooth too. Id suggest using a new layer of fastflash or their pink gap stuff, over/under will build up great.

    1. Ryan_SLC | | #8

      Thanks. That was a helpful website!

    2. finePNW | | #10

      Very helpful indeed -- thanks!

  5. Ryan_SLC | | #7

    On the other hand, Benjamin Obdyke shows their liquid flash first, then their UV+ tape going over it.

    I also have read huber zip liquid is the same a prosoco...but then you hear Matt R. state prosoco has fiber that fills gaps better than zip...

    1. Patrick_OSullivan | | #9

      > I also have read huber zip liquid is the same a prosoco...but then you hear Matt R. state prosoco has fiber that fills gaps better than zip...

      That's a different Prosoco product: Joint & Seam Filler.

      1. Ryan_SLC | | #11

        oh. gotcha. Would be weird that the Huber/Prosoco story is true and Zip didn't have the same though...

        1. Chris_in_NC | | #12

          The Huber product seems to sit in the middle of Fast Flash and Joint & Seam Filler as far as physical properties, so it's almost like a combination of the two Prosoco products. That said, the Fast Flash is easier to gun and spread, and the Joint & Seam Filler seems to fill gaps better. I've used all 3 products on Zip sheathing, and they all work, they're just different.

  6. steve41 | | #13

    I've not had success in my taping tests over cured Prosoco FastFlash with typical flashing tapes (zip, siga, etc.). I did use a butyl based roof self adhered product that seemed to adhere very well to cured liquid flashing, though I did not perform any extensive testing. If I had no other alternative I would research further and do some testing with something like this:

    Again, I'm not suggesting that this is the answer... but it may be worth looking into.

    As a side note: If your bucks are liquid flashed, and you are using flanged windows, won't all but ~1/2" of the fastflash be covered by your window flanges? If this is correct than I would believe that using a tape like Siga fentrim 15/85 pre-folded would work well as the small area of exposed buck would not impact the full tape coverage over the Tyvek, over the flange, and up the window frame edge. Or just run the Tyvek under the window flange and then tape? Either way it seems like there is an option there. You'd still have to wet-set some Tyvek under the sill.... as shown in the Hammer and Hand link previously posted.

    Good luck!

  7. Ryan_SLC | | #14

    Old, but DuPont did get back to me. They said they have no compatibility testing on any Prosoco products to their products. I'm bumping because I had read a few places to ask the manufacturers for letters supporting their product with other products not on a compatibility sheet.

  8. nrosdal | | #15

    why tape? just use more fluid applied over the window flange. That is what i did and it was very easy fast and didn't not use all that much product (only 3 sides so that it can drain if water ever finds its way in).

    1. Ryan_SLC | | #20

      It's messy and hard to mil gauge on the flange...

      I would also say it's pretty questionable to assume compatibility of your window flange with Prosoco. How would you even know?

  9. tg_johnson | | #16

    We used 3m all weather flashing tape 8067 over the Prosoco fast flash and haven’t had any issues. We initially tried 3m 3015 tape because it says it adheres to difficult substrates but it didn’t work as well.

  10. Expert Member
    ARMANDO COBO | | #17

    This a bit off the topic, but a good reason to advocate the use of outsulation on top of the Plwd and sprayed-on WRB in all climate zones. Since window bucks go on top of the rigid foam, we have zero issues installing tapes on rigid foams, as long it's an approved tape by the foam manufacturer.

  11. nrosdal | | #18

    What do you mean bucks on top of the foam? That seems unconventional and I can't see why you would do it that way. Attached is my house under construction currently and this is what I would see as the nest way to do the buck and fluid applied (not that your way may not be better but am curious on the details).

    1. Expert Member
      ARMANDO COBO | | #19

      Usually, we install flat 1x4 window bucks on top of the rigid foam when we have brick or stone cladding to give solid stability and square frame to install the window fins. The buck on top of the foam also reduces the brick gap to the window frame.
      If we were installing fiber cement siding, the 1x4 bucks will match the 1x4 rainscreen.
      If we were to use stucco, we use 2x8 window edge frame on a 2x6 wall and allow the rigid foam to match the window thickness.
      I’m sure Northern climates installing thicker rigid foam, would need larger window edge bucks.

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