A single-pane window is usually built as true divided lit, meaning the window sash has a grille pattern that separates the individual panes of glass.

Insulated glass these days is usually 3/4 to one inch thick and too bulky to fit into metal frames made to hold single pane glazing.

Q: I have a large kitchen window that was installed around 1986. I don’t recall the manufacturer, but it could be Andersen. The window is single-pane glass with 16 panes, eight over eight, with ...