Windows are indispensable parts of a house. They facilitate the entry of light, air, and beauty to make your home into a comfortable living space. However, since we are so used to seeing windows in our daily lives, we seldom pause to familiarize ourselves with the specific parts of a window and its functions.
Knowing the anatomy of a window might not come in handy during your day-to-day life. But when it’s time for a window repair or replacement, being familiar with window terminology will save you a lot of time and research.
Anatomy of a Window
Depending on the style of window you have, window parts may vary. However, the ones listed below are the most essential parts of a window that you should know.
Window Sill
A sill is a flat piece of the window trim found at the base of a window. It is a fundamental part of the window structure because it prevents moisture from entering the house. The main difference between a window sill and a window stool is that sills are situated outdoors whereas stools are indoors.
Window Stool
A window stool is the bottom horizontal portion of the window. It extends inward from the bottom part of the sash, and is situated inside the house. Compared to sills, window stools are more visible, and often serve as a space for plants or decor.
Window Sash
The main function of window sashes is to hold glass panes together. Ensuring the stability of window sashes is important because a distorted sash can cause the window to not lock firmly and warp.
Head
The head is the uppermost horizontal part of a window frame. It spans horizontally across the window, serving as a support to prevent the full weight of the wall from resting directly on the window.
Glazing
Glazing is the glass inside of a window. It is often used as a general term to refer to panes of glass, which can either be single, double, or triple. Double-glazed windows are some of the most common for homeowners seeking insulation and security.
Jambs
Jambs are the vertical sides of a window frame. Occasionally, jamb extensions may be required for window openings that have greater depths.
Muntins
Muntins are the strips or dividers that separate individual glass panes in a window. Originally, the objective of muntins was to evenly distribute the weight of large windows, especially for older buildings. Nowadays, muntins mainly serve an aesthetic purpose.
Latch
A latch is a lock that holds sashes together. Latches are some of the most common types of window locks due to their convenience and simplicity, and are found mostly on single or double-hung windows. For increased safety, homeowners are often recommended to pair latches with other locks to reinforce security.
Stile
Window stiles are the vertical-edge framing parts of a window sash, and are positioned on each side of the window.
Parts of a Double-Hung Window
Double-hung windows are among the most popular window styles available. Homeowners often opt for double-hung windows for their timeless aesthetic as well as their tilt-in feature which makes cleaning convenient. If your next job is installing or replacing a double-hung window, here are some common window parts you’ll need to know.
Lift
Lifts provide easy opening and closing for double-hung windows. Sash lifts come in a variety of styles, including recessed and surface-mounted lifts.
Top & Bottom Rail
Every window has a top and bottom rail. They are located on the upper and lower horizontal parts of a sash. On a double-hung window. The top rail is the top part of the upper sash, while the bottom rail is the bottom part of the lower sash.
Check Rail
A check rail on a double-hung window is where the bottom part of the upper sash and the top part of the lower sash come together, also known as the meeting rail. Check rails also provide a more traditional and classic look for homeowners seeking vintage-styled windows.
Upper & Lower Sash
A unique feature of double-hung windows is the vertical placement of their sashes, with one stacked on top of the other. Lowering the upper sash allows hot air to exit from the ceiling, while raising the lower sash allows cool air to enter the room.
Sash Lock
Sash locks are locks for fastening a double-hung window. It is usually attached to the check rails in the center of the window unit. Though sash locks do not offer much protection when it comes to preventing break-ins, they are great for avoiding drafty windows.
Additional Window Parts to Know
Windows may seem straightforward in terms of design, but they actually consist of a variety of parts with specific functions and names. Apart from the above-mentioned window parts, here is a list of additional window terminology that could come in handy when it’s time for a window replacement.
Casing
Casings are decorative moldings that go around window frames to cover up the gap between the frame and the interior wall surface or the exterior of a building.
Weather Strip
Window strips refer to a strip of rubber or other material used to seal the joint between a sash and its frame to prevent rain, cold air, or snow from entering the room. Installing weather strips can also be a low-cost way to improve the energy efficiency of a house by preventing air leaks.
Weep Hole
Weep holes are tiny openings situated at the bottom part of the frame to drain water accumulated in window tracks. It is important to keep weep holes clear of debris and blockage to allow water to drain regularly.
Mullion
Mullions and muntins both refer to dividers on a window. The only difference is that mullions are vertical posts separating two or more window frames, whereas muntins are dividers separating panes of glass.
Apron
An apron is a piece of decorative and functional molding right beneath the window stool. It not only hides the gap between the window’s framework and the drywall, but it also provides a nice finishing touch to the window design.
With a thorough understanding of window terminology, you can recognize window parts with ease, and better prepare yourself to discuss window repairs with your clients. Ready to get started? Find all the window hardware and accessories you need at Zoro.
Product Compliance and Suitability
The product statements contained in this guide are intended for general informational purposes only. Such product statements do not constitute a product recommendation or representation as to the appropriateness, accuracy, completeness, correctness or currentness of the information provided. Information provided in this guide does not replace the use by you of any manufacturer instructions, technical product manual, or other professional resource or adviser available to you. Always read, understand and follow all manufacturer instructions.