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Community and Q&A

Zip System vs. OSB

Brian Ducharme | Posted in Energy Efficiency and Durability on

I am in the process of choosing between zip system and osb sheathing for the exterior of a new home project. I have read through a lot of articles on this site though I am still trying to decide on if it is worth the added cost if OSB is installed cautiously. I would still use a high quality tape on all seams. I intend to use a high quality sealant inside at the plates and blocking to sheathing joints. I also intend to install Tyvek on the exterior since the home will have vinyl siding and I don’t want to rely on the tape alone at sheathing joints (if using zip). Therefore I feel that there may not be much benefit to paying the additional cost for zip system. If I carefully install the OSB should I have any cause for concern with the air tightness performance of the wall?

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  1. Expert Member


    To me the choice would be between plywood and Zip. OSB works well as an air-barrier, but is too susceptible to any moisture the sheathing may be subjected to.

  2. user-1072251 | | #2

    It's been demostrated that plain osb does not work well as an air barrier, unless it's painted such as ZIP. I prefer fir cdx for the durability.

  3. jberks | | #3

    I have OSB sheathing on my current project and I regret it. Tapping is horrible, most of then don't stick, unless you roll on a primer, which is just more costs, labour, time.

    I was at a builders conference and got talking to a zip rep on pricing. After learning about what zip costs, I should have used it, when compared to the time spend priming, taping, sealing, and tyveking my OSB sheathing.

    Also in my case, I'm applying roxul outaulation, so I could have saved myself another step if I used zip 2" insulation sheathing.

    Next time I will also use zips liquid flashing for all the seams, liquid applied membranes are now my fave, since its so much easier to work with. Matt risinger recently posted a video on it.

  4. Expert Member


    You are right. I had forgotten about OSB's air-leakage problems:

  5. GBA Editor
    Martin Holladay | | #5

    I think you have read about the pluses and minuses of these sheathing choices. The further comments posted here clarify the issue.

    Either plywood or Zip sheathing is a higher quality choice than ordinary OSB. The only advantage of OSB is the low price -- so a lot depends on your budget.

  6. Brian Ducharme | | #6

    Thank you for the feedback. I think deep down I knew zip system was the right answer but was hoping that taped seems on osb was comparable. I think I’ll be going with zip.

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