Knowing what the parts of a window are makes it easier to communicate with contractors, shop for replacements, and feel more informed during the window selection and installation process.
It’s easy to become overwhelmed with all the terminology when trying to order a replacement window. If you can’t name the parts of a window, don’t worry. This helpful guide will walk you through each section of a window, making it easier to understand the function of each component for painless maintenance and replacement ordering.
If your home is in need of a window installation or replacement, get started today with a free quote from the window pros at MEI.
Parts of a House Window
Though there are design variations between different manufacturers and window types, there are a few components that every house window has. As shown in the above window parts’ names diagram, the main components include functional elements like the sashes and frames, as well as decorative pieces like grilles. We’ll dive deeper into each of these components and more below.
Frame
The frame is the outer, stationary component of the window. It holds the entire system in place within a building’s structure. A window frame is made up of the head, jamb, and sill, and they are commonly made from solid wood, fiberglass, or vinyl.
Pane
The window pane is the sheet of glass that fills the frame. It’s what allows light to enter the interior space while still protecting the home from outside elements. Windows can be single-, double-, or even triple-paned, representing the number of glass layers in the system.
Sash
The definition of a window sash is the component that holds the glass pane. Depending on the type of window, sashes may be movable, allowing the window to open. A sash is made of window rails, which are the horizontal pieces, and window stiles, which are the vertical components.
Weatherstripping
Weatherstripping provides a seal around the window frame, which helps to keep insects, drafts, and moisture out of the home. It’s used to enhance comfort and energy efficiency. Common weatherstripping materials include felt, metal, foam, or rubber to seal up any small cracks between the frame and the main building structure.
Mullion
A mullion is a vertical or horizontal bar that’s used to separate two or more window units within one large opening. Mullions help provide support, plus they offer a decorative element to the building’s exterior.
Grilles
Grilles are decorative strips of wood, vinyl, or metal that are meant to give the appearance of having multiple panes or special designs. They don’t have a structural role in the window system and may also be referred to as a grid or muntin.
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Parts of a Window Frame
As mentioned above, one of the key components of any window is the frame. The frame itself is comprised of three main components—the head, sill, and side jambs—all of which play important roles in the overall function, structure, and appearance of the window. Let’s take a closer look at the window frame parts’ names.
Head
The window head makes up the top part of the frame and is typically made with a wooden beam. It helps support and distribute weight from above the window opening, preventing the wall from cracking or sagging from a weakened structure.
Sill
The sill is the bottom part of a window frame, and may also be referred to as the window ledge. It sits horizontally, and often has a shelf-like appearance where people store small plants or knick-knacks. The sill supports the window structure, and its exterior portion helps direct water away from the home.
Stool
In some cases, manufacturers or contractors will refer to the interior and exterior parts of the sill as separate components. If so, the interior portion may be called the stool, while the exterior portion is what’s considered the sill.
Apron
Window aprons are the decorative pieces of trim that are placed on the interior wall, right below the window sill. Aprons play an aesthetic role in enhancing the appearance of the home, while also helping to cover any seams between the window frame and the wall.
Jamb
Window jambs are the vertical components of a frame. Looking at a window components diagram, the jambs are found at either side of the opening. Their function is to help hold the window sash in place.
Unique Parts to a Window Based on Window Type
Several components are universal to all window types, like the frame and glass panes. However, certain types will have unique characteristics. If you’re interested in casement, double-hung, or sliding windows, continue reading below as we cover some of the features that are unique to each type.
Casement Window Parts
A casement window is designed to swing open or closed rather than slide. They may also be referred to as a crank window, referencing the hand crank that’s used as the opening mechanism. Here are some of the unique parts of this type of window:
- Crank Arm: The crank arm and operator sit at the bottom of the window frame. The crank arm slides out, and you open or close the sash by turning the crank.
- Hinges: The window sash is secured to the frame with hinges on one side, the bottom, or top, controlling the direction the window will open.
- Lock: The locks are placed on the opposite side of the frame from where the hinge is located. Depending on the window size, there may be more than one locking handle to keep the window secure when shut.
Double-Hung Window Components
A double-hung window features two operable sashes. Both sashes can move on their own, allowing for more versatility with air flow and ventilation. The unique features of double-hung windows include:
- Upper & Lower Sash: The window has two sashes that move independently, one above the other. These sashes may include a tilting function for easier cleaning.
- Sash Lock: To secure a double-hung window, one sash will have a lock, and the other side will have a keeper, which engages to keep the window closed tightly.
Sliding Window Parts Names
Sliding windows, also known as gliding windows, feature sashes that slide horizontally to open and close. One or both sashes may be movable, with the entire system working similarly to a gliding door.
- Track: The channels located at the top and bottom of the frame that guide the sashes as they slide open and closed.
- Rollers: Small wheels between the sash and tracks that reduce friction and enable smooth gliding.
- Interlock Rail: A security rod placed in the track when the window is closed to prevent forceful entry.
Find the Right Windows for Your Home with MEI
If you’re in the process of replacing or installing new windows and you need some help understanding the different components, the team at MEI can help.
As the most trusted home improvement company in the Twin Cities, the experts at MEI will provide you with all the information you need to feel confident in your selection. Whether you need help finding the right window type for your home or determining the best time to replace your windows, we have you covered.
Reach out to our team today to receive a free window replacement estimate or explore our selection of residential-grade windows for commercial and residential properties.