46 Different Parts of a Window and Window Frame

Last Updated on November 25, 2021 by Kimberly Crawford

There are no homes without windows, so we must take these structures seriously. You might think that just because they are thereby default would mean that they are not worth getting to know.

It might be surprising for you but there are more than twenty parts of a window. There are even added parts for different types of windows. 

In this post, we will give you a rundown of these various parts and some of the window parts in specific types of windows. If you are here for all of these, read on. 

parts of window

Related: Parts of a roof | Parts of a door

Parts of a window

window parts

All window types have the following parts. It is easy to mix them all up especially that most of them are just tiny parts and they can be easily missed. Some of them are so unknown that most of us do not even know how they function.

To understand the anatomy of the window and to understand how they work and how you will take care of them, here are the parts of a window. 

1. Head

This is considered as the horizontal part of a window frame. It rests on the lintel and is attached to the topmost edge of the window frame and the surrounding wall. 

2. Interior Casing

This one is the polished trim that surrounds the frames of the window. Aside from enhancing the finished look of the window, the interior casing also prevents draft and cold air. 

3. Head Jamb

It is where the window sash rests. It is located on the uppermost, vertical side of a window frame. Head and side jambs are considered as interior structures of the window frame. 

4. Side Jamb

They are vertical strips that connect the sides of a window frame. It comes with a short strip called the jamb liner in which the window sash is placed. 

5. Sash Lock

It is basically the lock system installed in either a single or double-hung window. It reduces window-rattling by tapping with the lock strike. The sash is the moveable fixture of the window. It holds the glass panels on the horizontal and vertical frames. 

6. Upper Sash

It holds the upper part of the windowpane by being attached to the window’s framework. It basically holds the upper division of the glass panes. The upper sash offers all the natural light a window could let in. 

7. Stile

This one is usually located parallel to the window jambs. It is the vertical fitting of the window sash. Both the upper and lower sash have a stile. The stile is located on the sides of the window. 

8. Top Rail

It is the upper horizontal section of a window frame or casement.  

9. Bottom Rail

It connects the vertical parts of a window frame. It is also considered as the lowest horizontal section of a window frame. 

10. Balance

It is a spring-loaded mechanical device used to balance both sash’s weight every time you open or close the window. It is located on the jamb and it is more notable on hung windows. 

11. Stool

It is attached to the windowsill. It is also called the bottom horizontal shelf. It is where the windowsill descends. It is also where window plants are positioned. 

12. Lower Sash

Like the upper sash, it also holds the windowpane by being attached to the framework, only it is attached on the lower part. It is also called the lower calf of the entire window frame. Unlike the upper sash which provides natural light, the lower sash provides the view outdoor view. 

13. Channel

This would be the grooves surrounding the window frame. Its main function is to seal the window from water and debris. A channel is typically made of plastic or rubber. 

14. Exterior Sill

It is both decorative and functional. It is located in the external, bottom part of the window frame. It is horizontal in shape and it protects the window from over moisture when it rains or when it is too damp or cold.  

15. Apron

It is the raised part of a windowsill. While it is considered as more decorative than functional, the apron actually supports the sill. As a decorative element, it allows us to see what the inside of the home looks like from the outside. It is like an installed moulding. 

16. Weep Hole

This is a small opening along the windowsill which allows moisture to escape through. Through this, your windows are protected from locking or it being inoperable. 

17. Screen

This one is a protective fitting that keeps the insects from entering the home through the window while still allowing natural light and air to seep through. It is usually a woven mesh made of either fiberglass, metal, or plastic. 

18. Window coverings

They are also called window blinds. They are made of either hard or soft fabric materials. They include roller shades, shutters, shades, and all types of window blinds. They could also be curtains, fabric shades, or valances.  

Related: Types of window treatments | Do thermal curtains work? | Types of kitchen curtains | How To Fix Vertical Blinds That Won’t Rotate

19. Hinges

It is a glass panel that opens inwardly and functions for ease of access in the grilles and window shades. The most durable and go-to choice for hinges would be stainless steel. They are not prone to friction and at the same time provide a smoother surface. 

Parts of a Casement Window

casement window

This is a popular window type for homeowners. It is designed with fiberglass, wood or vinyl. It is opened or closed through a crank. You could overextend it so that you could get more natural air during hot seasons. A casement window is composed of the following parts. 

20. Lock Handle

It is located on the window jamb which acts as the lock system of the casement window. 

21. Operator

It is operated using a crank device which basically sets casement windows apart from others. It is the one used to open or close a casement window. Most of the time, it is even interchangeable with the crank itself. 

22. Casement

It does more of a decorative function to the window system. It is the frame or mold of a window. It covers the spaces between the window frame and the wall. The casement is used more in sliding windows because they offer greater insulation. 

23. Fanlight

A fanlight can be installed in a door or window. It is like a tiny window whose main function is to give greater ventilation for the entire room when you open it. 

24. Transom

This one works as a window divider. It horizontally divides the upper part of the window from its lower part. So if you only need the window half-opened, you have the transom to pull. 

25. Argon

It is labeled as non-toxic gas used as an insulating component for glass. It functions to reduce heat, UV and to keep your home cooler even during hot months. 

26. Aluminum Clad

It is an exterior wood part that is polished with aluminum. It has a glossy, smooth finish to be protected from harmful outdoor elements. 

27. Weather Stripping

It is made of a durable material used to cover the space between the sash and the window frame to prevent water or air leaks to seep through the window. On top of it, it adds more insulation to the room. As a watertight seal, it is usually made of metal, vinyl felt, or rubber. 

Parts of a double-hung window with circle head

Circle heads are usually done to provide more natural light in home offices, closets, staircases, and other entryways in the home or a building. If you are working with customized double-hung windows like those with circle heads, these are the three parts that you should know about. 

28. Fixed Panel

As the term implies, it is the structure of the window that cannot be operated. It is likable to a glass pane of a picture window. 

29. Grilles

These are decorative fittings that divide the window panels. They can be fixed, removable, or installed between the glass. 

Parts of window glass

Window glass is essentially the sheet of glass cut and designed to fit the window frame. It is also called glazing. Window glass can be tinted, insulated, or thickened. You can generally control the amount of light and air that comes in through the window depending on the window glass that you install. 

30. Windowpane

The windowpane would be the sheets of glass inserted within the window frame. They could be designed as single or double pane, made of glass or other ornate materials. They can be insulated by applying the surface with argon. 

31. Mullion

It is considered a major structural part of a window. It can either run horizontally or vertically. It works by combining the two window panels together. Unlike the transom, the mullion is basically the vertical separator of two parts of the window. 

32. Muntin

This one would be the fitting in between adjacent planes which creates the grid pattern in a window frame. It is a long strip usually made of wood, steel, or metal. It is also called the glazing bar. 

33. Window Film

This one is a thin laminate film spread over the window glass. It acts like a tint or insulator to control heat and airflow. It also serves as a barrier to limit the UV light which enters the room. 

Related: Why birds hit the windows?

Parts of a window frame

It is the exterior area of the window and it is also called the window casing. The window frame is one of the two major structures that compose the window. The other structure is called the sash. Window frames are mostly made of wood, vinyl, fiberglass, and aluminum. 

Related: Exterior window trim ideas and designs

34. Air Latch

It is the movable latch that keeps the window open regardless of the angle it is opened on. It is typically attached to the meeting rail when using a double-hung window.

It is in the stile of a casement window and it is positioned in the bottom rail of an awning window. It also helps the weatherstripping by adding another layer where moisture and too much air could be blocked. 

35. Aluminum Bracket

Its job is to offset the window away from the wall through a bracket system. It is made of aluminum. 

36. Glass Sealant

It is a protective coating usually applied to the glass panes for it to remain clean and dry. It is a silicon-based product and when applied, it could be foam, liquid, or gel. 

37. Hollow Glass

This is basically the windowpane. 

38. Pane

This is the glass sheet cut and inserted in a windowpane. 

39. Spacer

It keeps the windowpanes apart through an aluminum glass sealed in between two other glass panels. 

40. Meeting Rail

This is where the two sashes literally meet when the windows are closed. 

41. Sloped Sill

It is one of the window’s exterior parts. It is strategically sloped down so that water could easily runoff. 

42. Drain Hole

It is where the water and other fluids flow. It is a small metal channel attached to the frame. 

43. Lift Rail

This is the handle that you lift for you to open or close the window. It is usually found in wood and single and double-hung windows. 

44. Lower Sash

It holds the windowpane by being attached to the lower part of the window frame. 

45. Bottom Rail

It connects the vertical parts of a window frame. It is the lowest horizontal section of a window frame. 

46. Frame

This is the support structure of the whole window. It makes up the entire window’s parameters. 


Windows are more complex than how you conceive them to be. Of course, there are default parts of a window. These would be the sections that are found in all types of window systems.

On the other hand, there are specific parts that could only be found in specific types of windows. Some have seemingly overlapping functions and it is important that you know the similarities and differences of these parts. 

At some point, you will have to know how each one works and where to find them. Renovations are always on the loose and if you ever switch up your window design, knowing all of its parts may come in handy.