Fiberglass window not plumb, how to fix?
I had three Marvin Integrity All-Ultrex (all fiberglass) windows installed. One of them bows inward on one side (vertical). The instructions say do NOT screw through the fiberglass!
I intended to install shims every foot or so, and then insert screws. What to do?? I was going to do the same on both sides of all three windows so they would look uniform.