All the Parts of a Window You Need to Know About—and Why They Matter

The anatomy of a window is important. Here's a breakdown of all the major window parts.

Parts of a Window - Pretty Window
Photo: Courtesy of Marvin

Understanding the different types of window glass while picking out new windows or admiring previously installed ones is one thing, but what about the parts of a window? One aspect of appreciating what makes a window great is knowing how all the different parts work together. But if you can't tell the sash from the apron, you'll have a hard time articulating what, exactly, you like about the window.

No matter where you do your window shopping—we're partial to Marvin, makers of master-crafted, premium-quality windows and glass doors—knowing how to point out the window parts that you like and dislike will help you make the best window selection, changing the whole look and feel of your updated space in the process.

Learning how to hang curtains will help dress up your window selection, but picking the perfect windows—with just-the-right sash and ideal grille placement—will make window treatments more of an accessory than a way to make up for inadequate windows. Once you've found the perfect windows, you only need to learn how to clean them. You'll have bright, mood-lifting light in your space all day, every day.

Anatomy of a Window—10 Window Parts You Should Know

Apron: This horizontal piece of trim runs underneath the sill.

Glass: It's also called lite (industry terminology for the piece of glass used to create the window) or glazing. Four main kinds are available.

Grille: Also called grid or muntin, these decorative cross pieces divide the window into panes. Some grilles are suspended between the glass; others snap off for easy cleaning. Grilles for double-hung windows are named according to the number of squares they form (like six over six, as shown in the photo above). Not to be confused with mullions, which are vertical or horizontal pieces between adjoining window units.

Head: This horizontal piece forms the top of the window frame.

Jamb: These pieces form the top, sides, and bottom of the window frame (including the head).

Lock: Most new windows come with locks, and there are upgrades (such as magnetic locks) that allow windows to automatically lock when closed.

Rail: This is the horizontal part of a sash.

Sash: The movable part of the window, it's the framework that holds the glass in place.

Sill: This piece runs along the base of the window frame.

Stile: This is the vertical part of a sash.

Was this page helpful?
Related Articles