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Parts of a Window

Learn the common parts of a window, their function, and where they are on a window.

Check rail

A check rail is the horizontal part of a double hung window where the top and the bottom sash meet. Simulated check rails can be found on casement or glider windows to mimic the look of a double hung window.


A frame is what surrounds the glass or the sash of a window. A frame has a header across the top, jambs down the sides, and a sill at the bottom.

Head jamb

The head jamb is the horizontal piece that forms the top of a window frame.


Jambs are the two vertical sides of a window frame.


A lite is a separately framed piece of glass in a window.


A sash is the part that holds the glass in a window and is separate from a window frame. A sash can remain stationary or move.


The sill is the lower, horizontal piece of a window, and supports the frame.

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