Maybe I am using the wrong term...When I removed the original window, I
had nothing left except the 2x4 studs that make up the frame. Then of
course, you have a half inch of plywood, and the siding.

The original window butted right up againt the aluminum siding. So when
I removed the original window, I needed to do something with the
siding, like put a j-channel all around the perimeter.

If I have the window sit entirely on the frame stud, then the sill of
the new window, with it's drain holes, hangs over the plywood -not
good.


Keith