Jefnik Windows and Doors is your source for new windows and replacement windows. We provide sales and installation of vinyl windows, aluminum windows, fiberglass windows, awning windows, casement windows, single-hung windows, double-hung windows, single-sliding windows, double-sliding windows and picture windows, all available in custom shapes and sizes and in a variety of colour finishes. Jefnik Windows and Doors is based in Mississauga Ontario and proudly serves Mississauga, Oakville, Milton, Brampton, Etobicoke, Toronto and the surrounding GTA.