Trimming the Sides of the Window

With the Mitered method, you simply measure the side of the window from the top edge of the trim to the bottom and add the width of the J (the visible part). On the bottom end of the J you´ll cut a miter, like in this picture. Then make a notch in the other end like this. This will be used to help shed water with the top piece. Getting this cut right will just take a little practice.