Notch the vinyl.
How to install window trim over vinyl siding.
Install j channels at doors and windows and under roof eaves and rakes.
Cutting and installing the siding 1.
Pry off the vinyl siding and j channel from around the perimeter of the window.
Along the tops install j channel trim with horizontal siding and base trim with vertical siding.
Unscrew and remove the storm window from the outside of the window.
Install the tops first then the sides and then the bottoms of the window surrounds.
Use tin snips to trim off the metal flashing covering the exterior windowsill.
Place the piece of siding to be installed under the window along the bottom edge and hold it where it will be located.
Lock the notched.
How to install window casing for vinyl siding 1.