Understanding window components is crucial before updating or replacing them. It will enable you to make well-informed choices. So, you might be looking for a guide to know the different parts of a window. This article will help you in this regard!

The window frame and sashes are two essential parts of a window. However, each of these parts also consists of several other components. In addition to the sashes and framing, other significant window components include the casing, mullion, and window grids.

Each part of a window serves a specific purpose and adds to the window's overall effectiveness. In this guide, I'll go over all the necessary parts of the window, along with some other information that you might find helpful. So, let’s get started!

Parts Of A Window Frame

The window frame is the component that holds the other elements in place and supports the entire window. Several pieces, such as the head, jamb, sill, etc., make up the frame. Generally, manufacturers use timber, uPVC, fiberglass, or aluminum to make window frames.

Well, there are names for every component of a standard window frame. So, now, let's go over every window frame part:


The head of a window is the top, horizontal portion of a window frame. However, this part may also consist of numerous smaller components. These include the plaster, lath, parting bead, header, and stop on the inside. Moreover, there are also the sheathing, casing, drip cap, siding, and blind stop on the exterior.


The vertical portions of the window frame are called jambs. To be more precise, these are the outside window frame's sides. Well, your sashes will slide upward and downward on the outer edge with the aid of these to assist them. However, traditional double-hung windows might incorporate pulleys into the jambs' top.

Weep Holes

The weep holes are the individual perforations in the window frame that allow water or moisture to leave. Generally, you may find them in vinyl or metal window frames. These are essential parts of a window as they enable the drainage of precipitation gathering inside the window frames.


The lowest horizontal section of the window frame is known as the sill. However, a window stool is another name for it. Furthermore, the sill comprises numerous tiny sections, similar to the head.

It mainly consists of the sub-sill and the sill frame. Moreover, this part has the sheathing and siding on the exterior and the lath and plaster on the interior.


Under the stool or sill of the window, there is ornate molding or trim called an apron. The apron fills the space between the window's frame and the wall. This part helps give the window's interior a contemporary style and look.

Part Of A Window Sash

Window sashes are the internal "frame" that supports a single glass pane. Any knobs or operating mechanisms for the windows are typically affixed to the sash and constructed from the same material as the window frame. Pane, weatherstripping, sash lock, lift, etc., are some notable parts of a window sash.

Sashes glide upward and downward for opening and closing windows that are single-hung or double-hung. However, sashes on casement windows swing open. Now, let's discuss the parts of a window sash:


A window pane is simply a window glass. In some situations, manufacturers use muntins, which resemble grids, to link panes to the sashes. However, window panes might be one, two, or three layers thick to increase efficiency.


Individuals install weatherstripping around the window sash and frame where two substances intersect. In addition to adding a second layer of weather resistance, it also increases energy efficiency.

Nowadays, weatherstripping is frequently composed of robust, flexible materials like rubber, silicone, foam, or vinyl. However, it used to be constructed of pliable metal, such as brass, in the past.

Sash Lock

A sash lock is a component on either a single-hung or double-hung window. It stops the sash from swinging around in the frame. So, this part is a locking system that keeps the windows safe and prevents them from rattling.

Window Rail

The window rails are the sash's top and bottom portions. There are mainly four rails. And two of them are on the top, and two are on the sash's bottom in double-hung windows. On the other hand, a check rail is present in single-hung windows.


The window frame has spacers at both the bottom and top. This part supports a minimum of two or more glass panes, aiding in insulation.


The handle used to lower or raise the sash is called the lift. One can use the lift to move the window in a double-hung or single-hung window.

Other Window Components

The window includes more than just the frame and the glass. It has many other components, such as mullions, grilles, casing, etc.

Additional components may be present in more intricate or ornamental window types as an aspect of their elaborate design. However, the following are some other window parts besides the frame and sash that are present in most windows:


Mullions are structural elements connecting two separate but tightly spaced windows. Both horizontal and vertical mullions are available.


Casings are the moldings that surround the window frames outside the house. They keep external air from getting into your home by sealing the structure.


A window grille is a purely ornamental element that gives the impression of dividing a vast window pane into multiple smaller panels.

It was not yet possible to produce robust enough glass to withstand larger pane sizes. So, this grid structure was required to make big windows in the past. Due to their high price, individuals regarded them as a prestige symbol in keeping with the vogue of the time.

However, they are no longer physically necessary due to advancements in glass manufacturing. So, people frequently set them on top of one large window pane as an ornamental but unusable addition.

Energy-Efficient Window Attachment

Along with window components, the terminology regarding energy efficiency might be confusing for the ordinary individual. So, let's discuss a few energy-efficient window attachments for your convenience:

Low-E Glass

The complete form of low-E glass is low-emissivity glass. Well, it is a type of glass that saves energy. It helps control the heat entering your house by filtering the amount of sunlight that comes in. As a result, it makes the temperature in your home more stable.

Argon Gas

Individuals generally use colorless and odorless argon gas as insulation in double and triple-pane windows. It keeps the temperature of the windows closer to the indoor temperature. When combined with Low-E glass, it helps to reduce drafts and increase energy efficiency.


It is essential to educate yourself on various window components before making a purchase or starting a project that requires constructing windows. Hopefully, this article on the different parts of a window was helpful in that regard. Thanks for reading through.

January 18, 2023 — Della Wang