Screens that hinge over UPVC, metal casement or louvre windows require a  sub-frame to avoid handles and fasteners. It is preferable to hinge the screen to the sub-frame and remove it before mounting the sub-frame to the window. To hinge the screen see "Hinged Screens" There are three alternative ways to mount a sub-frame to a window. Drill a pilot hole through the face of the sub-frame and secure with wood screws. Use a " liquid glue" solution to hold the frame in posistion. Double sided tape used on the corners will hold the frame in position while the glue sets. Fill any gaps between the sub- frame window with decorative silicone filler. Hold the sub-frame in position with double sided tape as above, drill pilot holes from the outside through the rebated window section of the frame (where the closing light would be) and fix through into the sub-frame with wood screws. This has the effect of not showing any face fixings. Re-fit the screen as before and hold closed with the turn buttons.   COMING SOON !