Window Lingo: Shedding Light on All the Different Parts of a Window

Bry'Ana Arvie
Written by Bry'Ana Arvie
Updated April 27, 2022
Woman at home opening the window
Photo: Westend61 /Westend61 / Getty Images


  • Most windows have 10 universal parts, and up to 15 additional parts.

  • The number of extra parts depends on the window style and type.

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Your windows do more than just offer a beautiful view outside while letting natural light pour into your home. Windows have several parts that are crucial to keeping them working well—and certain types even have extra parts to boot. So if your window ever needs some TLC, you should be armed with the right information before calling a window repair pro. This guide will give you the window vocab needed for window replacement or repair.

Universal Parts of a Window

A wooden window open
Photo: Catherine Falls Commercial /Moment / Getty Images

Here are some of the common parts of a window that most window types share:


The frame supports the window and consists of the head, jamb, and sill. 


Of course, this one’s self-explanatory; the glass, also referred to as a pane, is the window’s glass portion. 

Acting as the head-honcho of the window, the head is the horizontal jamb at the top of the frame. 


Your window jambs are the vertical sides of your frame. 

Jamb Liner

A jamb liner is a strip located on the inside of your window’s frame, providing a tight fit for your windows. 


Your window rails are the horizontal top and bottom components of the window sash. 


The window sash is the movable section of a window that holds the glass.


The sill, also referred to as stool, works as the horizontal jamb at the bottom of the frame. 


Stiles are the vertical portions of a window that holds it together at its sides. 

Weep Holes

A window’s weep holes are small holes located at the bottom of a metal or vinyl window to allow for proper drainage of precipitation on the window. Its purpose is to protect the window sill from rotting and causing water damage inside your home.  

Additional Parts of a Window

Now that you have a good idea of some of the main parts of your window, let’s cover some other less common or window-specific components that you should know:

Aluminum Cladding

While not all windows have it, aluminum cladding is aluminum surrounding the window’s sash and frame, acting like a protective layer on wood windows.   


The apron is the decorative trim underneath the sill or stool of a window located on your wall. 


Found on some single- and double-hung windows, balances are located inside the window’s frame and work as a counterbalance weight, helping you open and close it.  


The trim border around a window is known as its casing, and it’s useful for hiding flaws in drywall cuts. And most window casings are made of wood, pressboard, bamboo, extruded plastic, plaster, or hardwood veneer. 

Check Rail

The check rail is a window component commonly found on double-hung windows. It’s located in the middle of the window and is the rail where the upper and lower sashes meet. 

Fixed Panel

Typically found on single-hung windows, fixed panels are a portion of the window that’s stationary and can’t move. 


Grilles, also known as the muntin bar or windowpane divider, are decorative bars on the window that give the illusion of multiple panes of glass. 


Hinges hold your window’s sash to its frame, keep it stable, and allow it to swing outward or inward, depending on how they’re installed. 


A lintel is a load-bearing or decorative architectural feature spanning the area above a window. Lintels are generally structural in Western architecture and ornamental in Eastern architecture.

Locking Handle

This handy tool allows you to lock your window’s sash when you’re not using it, mostly found on casement windows. 

Insulating Gas Units (IGU)

While you can’t see it, argon or krypton gas is found between each pane of glass on double- or triple-hung windows, increasing your home’s energy efficiency. 


A mullion is a horizontal or vertical division in your window that holds, supports, and separates panes of glass. 


Commonly found on casement windows, the operator and its handle are what move the window sash open and close. 

Sash Lock

Standard on double-hung windows, sash locks allow you to lock your window and keep the sash from rattling. 


On the outer-facing side of your window, a window screen is a mesh screen made of fiberglass, metal, or plastic that protects your home from external elements such as insects, dust, and dirt.  


Typically used in double- or triple-hung windows, spacers are strips of plastic, metal, or foam found between each pane of glass to create an air-tight seal to help contain the gas insulators for more effective insulation. 


Your window’s weatherstrip is an additional piece of material around your window’s frame and sash to perform an air-tight seal to offer protection from the elements and boost energy efficiency.

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