Is the foam on ICF an air barrier? – GreenBuildingAdvisor

New to the site here, first post.  Forgive me if I do something “wrong”.  New construction, working on the design.  I live in the south, and would like a fully encapsulated attic space.  I plan to build using ICF for a variety of reasons this post isn’t about.  However, my question is this:  How do you create a continuous air barrier from the ICF wall up to the roof?

I’m drawn towards the “monopoly” framing concept, of taping directly from the wall to the roof.  More specifically, can you tape (using something like Siga Wigluv) from the *foam* of the ICF to the roof air barrier?

I’ve seen people on this site indicate the foam is not an air barrier–only the concrete core is.  However, this letter (https://www.nudura.com/media/2934/nudura_air_barrier_report.pdf?sfvrsn=0) makes me believe the foam is also an air barrier.  Does anyone have insight on this?

Kody Horvey (Canadian builder on youtube who uses ICF) regularly tapes/seals directly to the foam, and he gets fairly air tight numbers.  Curious if anyone has had a different experience.