Air sealing when working with heavily punctured osb
We will be installing new siding on our house and as part of the project we are adding exterior insulation. The house previously had vinyl siding and 1/2″ polyiso when we bought it. The polyiso was installed very poorly and as we are in climate zone 6, wasn’t a good choice in the first place. That has been removed. We would like to air seal as best as we can, but the osb sheathing is full of thousands of nail holes from the previous siding and foam and no longer have a nail in the hole. My question is what is the best way to air seal in this situation. My understanding is that best practice is to tape the sheathing joints, but I assume this is pointless with all the holes in the field of the sheet? Our install will be the existing OSB, Hydrogap WRB, 2″ Halo Exterra, furring with rainscreen gap, and then LP Smartside. Do we need to caulk all those holes? Should we use the WRB for air sealing and tape it to the foundation? Would the Halo Exterra be a resilient enough air barrier? What would you do in this situation? Thanks for the help!
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Replies
Use a peel and stick wrb
It seems that a peel and stick wrb would make the most sense in your case.
Having recently gone through a similar wall build assembly, I noticed a few things you may want to research further:
1. The Halo Exterra is 10psi. I believe code calls for min. 15psi for use under rainscreen furring.... but perhaps your area has different requirements.
2. Zone 6 requires min R11.25 exterior insulation when used, and 36%min of total insulation is to be rigid (exterior). The Halo product is R5 per inch, so R10 in your case for 2". This would not meet code. You also need to be mindful of the 36% ratio.
Best of luck with your project!