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What Are the Different Parts of a Window?



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  1. Window Frames
  2. Window Sashes
  3. Other Window Parts
cross section of window showing its parts and technical drawing

A cross section of a window showing parts and a technical drawing. Can you identify all the different parts of this window?

When you’re shopping for windows, it helps to know what the different parts of a window are. Like most building materials, windows have their own lingo that’s clear to installers but not to an unfamiliar homeowner.

This glossary will fill you in on the basics and point out some things our installers do when we measure your windows. When you know a bit of window terminology, you can feel more confident in your purchase.

Window Frames

The window frame is the part of your home that surrounds the installed window. When our installers put a window into your home, they attach it to the frame. Frames can be made from wood, metal, vinyl, or other materials. They have three main parts:

  • Head – The top of the frame
  • Jambs – The sides of the frame
  • Sill – The bottom of the frame

When we measure your home for windows, we will measure this opening’s width, height, and depth at different points. Window frames aren’t always exactly the same, so installers use multiple measurements and shims to center your window properly in space.

Depending on your window, your frame may also have a decorative apron underneath the sill and weep holes for drainage.

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Window Sashes

A sash is the part of your window that moves to open or close the window. A window with one sash is a single-hung window, and one with two sashes is a double-hung window. Fixed panels are window panes that don’t move.

The top and bottom parts of the sashes are called window rails. Sashes also have a lock to keep them in place, as well as a handle for moving the sash called a lift. Between the sash and the frame, you may have weatherstripping for insulation. In a double-hung window, a check rail keeps the two sashes from moving past the middle of the window.

Finally, the glass part of the window is called a pane. Window panes may have multiple layers of glass with gaps between them. This means the pane is insulated. There may also be decorative work on the pane to make it look like multiple panes of glass. This piece is called a grille.

Other Window Parts

If you need to connect two windows side by side, there is a piece called a mullion that links them together. On the outside of your house, special molding might surround your window to cover the gap in the frame. This molding is called casing. Your windows could also have screens to keep bugs out while the window is open.

Little latches hold some windows up along the sides, but other models have a balance system to hold them open or shut. In older wooden windows, these might be actual ropes tied to pulleys and weights that rest in the window frame. Modern windows usually use springs for balance.

Your windows could also have special parts because of their design. For instance, a casement window opens from side to side on a hinge and crank system. Our window dealers can point out the special features and parts of more exotic window types.

As long as your chosen window can fit inside the space of your home’s frame, our installers can place any window type you would like into your home. Try looking at your current windows and naming all their different parts!