I've got a UPVC double-glazed window that is perfect for my purposes except that it is 1/2" too tall. You might ask me why I don't make the opening bigger, but it's really not easy, as the house is built of hard stone, and there is a shaped stone sill at the bottom and a stone lintel at the top, both of which I'd like to avoid carving up.
I wonder if I can take 1/2" off the bottom of the frame with a circular saw. Once the window in place and securely bedded in with expanding foam, the fact that I cut 1/2" off is not likely to cause any problems, is it?
(The window is about 33" wide and 56" tall. The bottom half has a fixed pane and the top half has a top-hung opening.