Vapor retarder in ceilings?

I have a question about vapor retarders or barriers in ceiling assemblies, can anyone reference a code section that would clearly say that the barrier is required for ceilings with ventilated attics.


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I haven’t had time to look it up, but I don’t think it is or it may be subject to climate zone. Certainly not done here in the southeast. I’ll research when I get a moment.

In MN, vapor retarder and air barrier is required on the warm-in-winter side of wall and ceiling assemblies when insulated with anything except closed-cell foam. Not sure about Illinois.

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