I may have screwed up the custom window measurement, or not.
I am trying to fit a new window w/ frame into the frame of the old window (old frame still in place). As a result, I have a window with two sills (see photo). I want to keep the old will. Should I simply cut off the sill from the new frame?
The other alternative is to order a new window w/o frame to replace existing. This will also avoid coming short on the 4 1/2" trim (no brick molding) with the shingles.
Another option is to order a low-E pane and affix, somehow, to the old single unit window (6 panes). Has anyone done this before?