Ideal window depth to minimize window perimeter thermal bridging through frame
I am replacing the windows and redoing building envelope in my 30 year old house. Currently have 2×6 framed wall, covered with 5/8 tentest type fibreboard and then wood siding. Windows are original 30 year old solid wood. I am replacing windows with the following: Basic flush mount vinyl high efficiency windows, 4 5/8 thick with interior jamb slot for interior trim to be added to. For building envelope, I am removing Tentestboard and siding, and new wall will consist of 2×6 framing, covered with 7/16”OSB sheathing, DuPont Drainwrap, Silverboard Graphite XS cap nail fastened, and then covered with a rainscreen consisting of vertical 7/16 strapping with coravent SV3 top and bottom, and then finally horizontal 1/2 strapping on top of this. The double furring is installed to allow for installation of Maibec shingles and provide the proper drainage plane. My plan is to install the windows at 1/2” beyond the foam exterior, so basically approximately 2” out from wall frame studs. The horizontal 1/2” furring strips will be stepped out from the window to allow for a 1/2” piece of trim to surround the window, and then on top of this will be the finished trim 5/4 thick top and sides, and a deep angled sill on bottom. So, based on the detailed description of this building envelope upgrade, the dilemma I face is determining the ideal window depth, and minimizing any thermal bridging from the perimeter if the window is too far out. Not sure if I need to insert window closer to surface of foam and then make trim thicker to accommodate for this. I’d like to use a product like Thermal Buck, installed flush to the silverboard foam surface to allow for a better nailing surface and not compress the silverboard with the furring strips, however my windows are already on order and rough opening won’t accommodate the lip of the Thermal Buck. I thought about maybe purchasing Thermal Buck and trimming the lip off of it, basically creating 1” thick rectangle that I would picture frame install around opening and make flush with the foam. Any alternatives or suggestions?