Zip System vs. OSB
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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Replies
Brian,
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.
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.
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.
Bob,
You are right. I had forgotten about OSB's air-leakage problems:
//m.etiketa4.com/blogs/dept/musings/osb-airtight
Brian,
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.
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.