Following my earlier question about Air-Sealing on Piers (https://www.greenbuildingadvisor.com/question/air-sealed-on-piers-open-to-the-elements), I wonder about humidity in the assembly and i-joists.

I read the specs on some that are available in my area of Minnesota and they give a little note at the end which says to avoid high humidity (which we often have in abundance during the summer).

It seems to me that 2×10 or 2×12 dimensional lumber would suffice for the joists to give me enough insulation space, but my contractor neighbor keeps pushing i-joists for this project. I respond with the aforementioned concern about humidity. We’re at an impasse.

Would not the thermal bridging where the underside sheathing meets the i-joists also allow enough humidity that the adhesive between the bottom flange and the webbing would fail?