Is the foam on ICF an air barrier?
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.
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Very low density EPS in relatively thin sheets is likely not an air barrier, but the higher-density type used in ICFs probably is. Nudura is a reputable company and an engineer has staked their license on it being one, so I think it's ok to assume that it is. But I don't work with ICFs or use EPS as an air barrier so I don't have deep knowledge on the subject.
I have read some ICF planning and installation manuals, so not an expert - but a self adhered membrane such as Colophene ICF or ProtectoWrap are suggested in manuals for water proofing the exterior.