Size-adjustable window insert assembly

Abstract From the Canadian patent

A window insert assembly is disclosed having a spring-biased frame construction used to secure the insert within existing window frames of varying size. The insert assembly is particularly useful for mounting interiorly of an existing window pane to form a "double pane" insulative window structure, i.e. by creating a thermal cavity between the interior side of the existing window pane and the window pane of the insert. The insert assembly comprises a solid pane such as a glass, pane, mounted in a first frame. The first frame is received within a second frame which has movable sides for changing the size of the second frame. Springs are provided between the second frame and the first frame …