Your Guide to Window Anatomy


Pane refers to a single, contiguous peice of glass. More broadly speaking, a light is a section of a divided sash, and can refer to the pane or the section that the pane fits into. Lights are divided by muntins. An undivided sash can be referred to as "single-light."

To say that a sash is "double-pane" can lead to confusion, as that can also refer to thermal or insulated glass that is made up of two pane layers.

A window that has a three-light upper sash and a single-light lower sash, can be referred to as a "three-over-one" window.

diagram of a window highlighting the windows lights or panes