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Community and Q&A

Outside Corner Zip Sheathing – Tape or Not?

stuartd | Posted in General Questions on

What happens if a builder does not tape the outside corners of zip sheathing (NOT zip R)? In addition, some of these corners are not installed such that one side overlaps the other … some corners have a gap where the corner bead is exposed.
Would taping in a haphazard way, leaving bubbles, etc. be worse than leaving it exposed, which may make drying easier if the sheathing became wet? What about bug infiltration?

Corner is covered by vinyl siding corner piece at the moment, but builder is willing to remove and redo.

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  1. nynick | | #1

    If I went to all the expense and of trouble of using Zip and taping the seams, I sure as hell would tape the corners.

  2. Expert Member
    Michael Maines | | #2

    The corners should be taped. All ZIP tape should be installed flat and--importantly--it must be rolled for the adhesive to fully adhere. Best practice is to overlap sheathing at the corners but that's pretty rare these days and not a problem if it's not done. If you're concerned about bugs getting in from the bottom, squirt a little caulking into the gap.

    If it's not taped properly, they should remove the tape and start over.

  3. monkeyman9 | | #3

    I'd tape it if it were me. Kinda doubt it would leak water, but I'd want it for air sealing either way.

    None of my sheathing is overlapped, I just put caulk on the bottom of the corner. Bugs, rodents tend to eat spray foam.

    On the horizontal runs you don't want the tape bunched up or bubbled near the edge. Once it temp cycles in sun enough it may leak.

    1. Expert Member
      MALCOLM TAYLOR | | #9

      "Kinda doubt it would leak water"

      Zip only acts as an effective WRB because it is taped. The primary job of a WRB is to keep out bulk water. It's very likely it would leak.

  4. Expert Member
    Akos | | #4

    Outside corners of a building are one of the most exposed part of the house. Even with overhangs, if there is water damage, it will be there.

    Along with windows and doors, this is the one area of the house where you don't want to skimp on waterproofing, so tape is a must.

  5. Expert Member
    BILL WICHERS | | #5

    Proper taping is important enough that they print text on the tape saying it needs to be rolled. The reminder is basically built into the product. That should give you an idea of the importance that manufacturer puts on proper taping.

    Zip has basically two advantages over regular structural sheathing: the first is that it is generally regarded to be a superior grade of OSB to what you would normally get a the lumberyard, and the second is that it has a factory-applied WRB. If you don't properly tape Zip, you compromise the factory-applied WRB, at which point you aren't much better than if you'd just used regular OSB.

    Absolutely tape it properly. Taping is relatively simple, it isn't difficult to do correctly.


  6. walta100 | | #6

    Seems to me you and your builder have very different expiations for this build.

    I am guessing you are expecting a tight well insulated house and paying extra for Zip system. It sounds like you builder is building same leak boxes he did 50 years ago just using OSB that comes with green paint on it.

    It is clear you builder refuses to spend a few minutes to read the zip instructions or watch Zips YouTube videos and learn anything about the products he is installing.


  7. stuartd | | #7

    Thanks for your help, excellent advice, I'll have corners taped one way or the other. As Walta surmised, yes builder in business for decades, but actually has been responsive to my building science-based requests for this project.

  8. walta100 | | #8

    If the contractor is not going to do the training you may want to at least watch the training videos so someone on the job site understands how it should be done.


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