Exterior insulation window detail – GreenBuildingAdvisor

Hey all, please see photo for better understanding of what I am about to describe.

I am wrapping my timber frame with polyiso foam board. 2 layers of 2″ on my walls. When I got to my windows, I became hesitant on butting up my polyiso directly to the bottom flange of the window. I purposefully left this area zip tape free in case water got behind the windows, it could escape. However, if I butt the polyiso to that, it pretty much defeats the purpose. Especially once I add my strapping and suck everything tight. (FYI, I know a lot of people build a structural buck that their windows sit on, and then the window is outboard of the foam layer. However, in my case, my windows are framed directly to my zip layer, and I built 5/4 x 6 “window trim bucks” to accommodate my thickness

As you can see in the attached photo, I left the areas below my windows open, and I started thinking of purchasing some rockwool comfortboard to put in its place with the idea that at least rockwool can drain water a bit. I am not sure if this is worth doing, but it sounds like it kind of makes sense in my brain, ha. Let me know what you guys think, thanks!