Revisions log for Answer #2216

That you want to lay the OSB boards at a distance from the insulation makes sense. However, I would leave a few larger gaps at the boards so that the air can really circulate.

I think your plan is critical. The attic would then be insulated but still unheated. All around closed with foil, so no air circulation. Logically, the air will stand there and very likely become a problem at some point. You would then have to design this open to the OG, but open an existing insulation level I would think twice. As it sounds it is also still very easy to renew or strengthen the insulation if necessary. From such a thing I would keep open for me