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Taped ZIP over polyiso, over taped plywood; can I omit taping the polyiso seams?

chrisd_innc | Posted in Energy Efficiency and Durability on

I’m almost ready to put the metal roof on my 12×20 shed/shop, which I’m building as a small-scale test bed for materials, processes, etc.

At the moment it has a bare plywood roof deck with taped seams.  

I was protecting it with a layer of Titanium UDL (fastened with cap nails) for a while, and then decided to totally remove the UDL today after some spot checks revealed some leaky cap nails.

Now that it’s uncovered, I’m letting it dry out, at least overnight.  So now I have taped plywood with a bunch of little holes from the removed cap nails.

I will be adding one layer of 1″ polyiso, and topping that with a layer of taped ZIP.

So now the questions:
Is it necessary to fill/strike all the empty cap nail holes in the plywood with FastFlash for air sealing?  I hope not. I’m only concerned about condensation damage, not blower door scores.

Is it necessary to tape the polyiso seams if the outer layer of ZIP will have taped seams?
My intuition says the taped ZIP seams should perform that function, as the location of the air barrier is just moving from foam to ZIP.

Climate zone 3A, north of the Warm/Humid line.

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