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Community and Q&A

Sill plate flashing

WinnDesign | Posted in General Questions on

I’m in the process of building a new home where we’re using ProtectoWrap Triple Guard Energy Sill Sealer and Zip R-Sheathing. The idea was that the sheathing would be in the same plane as the foundation wall, run down to the top of it and be flashed with the Sill Sealer. Unfortunately the framing crew set the sill plate flush with the foundation wall and, because we have a brick veneer planned, had to set the sheathing on top of the sill plate instead of covering it (see attached image). Another issue is that they didn’t brush the face of the foundation before trying to adhere the Sill Sealer and so it’s not adhering in many locations. My initial thought was to cover the sill plates, while overlapping both the sheathing and Sill Sealer with 6″ ZipTape and maybe apply some acoustical sealant between the Sill Sealer and foundation wall in any locations where it wasn’t sticking. We’ll also be spraying closed cell foam on the interior side of the sill plates.

Should I bother with the correction I described, do something else or just move on?


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  1. GBA Editor
    Martin Holladay | | #1

    Is this a slab on grade, a crawl space, or a basement foundation?

    I'm not sure why the fact that you will be installing brick veneer resulted in the sheathing installation shown in the photo.

    Clearly, you'll have air leakage issues. I'm not sure whether Zip System tape sticks to concrete -- but Siga Wigluv tape does. (Siga Wigluv is often used to seal an exterior crack between the mudsill and a concrete foundation.)

    One way or another, you need to seal these cracks with air-sealing tape.

  2. WinnDesign | | #2


    It is a basement foundation. Again, we'll be spray closed-cell foam at the bands on all levels so we'll have some air-sealing in addition to whatever we do on the exterior.

    My comment regarding the brick veneer was simply to say that, after the sills had been set, the R-sheathing couldn't be applied to the face of the sills or it would encroach on the requisite air space behind our brick veneer.

    I'm not sure if Zip Tape will stick to concrete either but I'll ask my rep. If not, I'll see how quickly I can get my hands on the Siga Wigluv tape.


  3. WinnDesign | | #3


    Are you sure the Siga Wigluv tape will stick to concrete. Concrete isn't on their website's listing of suitable substrates. What do you think about us using a liquid-applied like Zip Liquid Flash?

    Thanks again,

  4. GBA Editor
    Martin Holladay | | #4

    I've heard good reports from builders who have used Siga Wigluv at the location. I thought I had a photo, but I can't find it.

    The photo below shows something different -- a combination of Siga Wigluv and Siga Fentrim. I took the photo at a job site in New Hampshire. Siga advertises Siga Fentrim as suitable for concrete.

    You might want to call one of the tech help people at 475 High-Performance Building Supply to ask their advice.


  5. Stockwell | | #5

    This is why I want to be around when my house is being built. Getting the details right is critical. I would make them tape up or use fluid applied on every overdriven nail in your Zip as well.

  6. WinnDesign | | #6

    Just FYI...

    After speaking with a variety of manufacturers, the solution I decided to proceed with was to spray 3M Super 77 adhesive anywhere we weren't getting good adhesion under the Sill Sealer. That should work but, in event it doesn't in some locations, the next step would be to use a brushed-on primer.

    The gap between the Zip Sheathing and the sill tape will be covered with 6" Zip Tape.

    Thanks for your feedback!


  7. Jon_Lawrence | | #7


    I am using Siga Fentrim to seal the mud sill joint - see picture. It sticks to concrete, wood and Zip sheathing. The 9" wide roll allows me to cover the entire area and meet the minimum 2" concrete overlap requirement. I am not sure if it will stick to a waterproofing membrane, which I assume is the black covering your concrete, but I can try it on a waterproofed are of my foundation wall tomorrow.

  8. Expert Member
    Michael Maines | | #8

    For what it's worth, 475 sells Pro Clima products; Siga is sold by Performance Building Supply and Small Planet Supply. Steve Konstantino, owner of Performance Building Supply, told me recently that Siga Fentrim is now their go-to product for this location, because it sticks extremely well to concrete.

  9. GBA Editor
    Martin Holladay | | #9

    Thanks for correcting me concerning the rival tape distribution outlets operating in the U.S.

    And I guess there is a reason that the photo I took shows Siga Fentrim. Thanks.

  10. WinnDesign | | #10

    Jonathan & Michael,

    Thanks for the suggestion. I think the Siga Fentrim is exactly what I need!


  11. user-6184358 | | #11

    The sheathing not attached to the sill plate could be a major structural issue.

  12. jpavia1 | | #12

    I've had nice results using Pro Clima's CONTEGA SOLIDO EXO to seal the Zip sheathing to the foundation. Since it's vapor-open it works great around windows also!

  13. Stockwell | | #13

    I am not a Zip expert(or fan), but in Joe's picture, aren't those overdriven nail mushrooms an eventual problem?

  14. jpavia1 | | #14

    Yes, they are. Good eye Kevin. I pointed them out to the framer and they were eventually taped

  15. kevinjm4 | | #15

    This is a great thread. I’m working on the same thing however I am using just plywood sheathing under a rainscreen.

    I heard going with Siga Fentrim is a good way to go, especially if primed first.

    I’ve got a question for all of you though... I’m not primarily going to be using this as an air seal, but more of a way to protect bottom couple inches of sheathing from moisture. Is this overkill for this particular goal - would there be a better, more cost effective solution for what I’m going for? Is there a good detail out there to follow...

    Thanks, wasn’t sure if this was appropriate or not in an already started thread to ask a question - but I saw the product I’m looking at in question so thought I’d just ask here... sorry if this in error on my part. I’m new here!

    Thanks again.

    1. maine_tyler | | #16


      "I am using just plywood sheathing under a rainscreen."

      Is this to imply no WRB? Is that a thing: just plywood--> rainscreen--> siding?

      1. kevinjm4 | | #17

        Sorry, yes there is a wrb- tyvek homewrap

        1. GBA Editor
          Martin Holladay | | #18

          You don't need to use tape at this location to protect sheathing.

          Here are the principles:

          1. You want to minimize splashback by three approaches: (a) keep the grade at least 10 inches below the lowest wooden components of your house, (b) make sure that your roof has adequate roof overhangs, and (c) install gutters at the eaves of your roof.

          2. The siding gets wet from rain. The sheathing shouldn't get very much exposure to rain at all.

          3. The WRB protects the sheathing from any water that gets past the siding.

          4. The ventilated rainscreen gap (between your WRB and your siding) helps everything dry quickly after a rainstorm.

        2. maine_tyler | | #19

          If you really wanted to seal the tyvek to the concrete it might be a wee bit cheaper (depending on if you already had some primer handy) to use something like Contega HF (a tube sealant that sticks to concrete). I do think they recommend the primer for concrete though.

  16. delson | | #20

    Which primer to promote adhesion of tape to concrete?

    1. jmidway22 | | #21

      I would look at the manufacturer recommendations. Since the tapes can have different binding materials, you want to make sure the primer doesn't degrade it. I had looked up Duponts flashing tape primer recommendations but forget. Believe it was a locktite product.

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