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What Is a Transom Window? Advantages, Disadvantages & FAQ

Person putting seal in a window

Most of us have seen transom windows somewhere, even if we didn’t know their name at the time. These stylish little windows help promote natural light and sometimes ventilation, and they can be found on commercial, government, and residential buildings alike. In fact, 10 Downing Street in London has perhaps the most iconic transom windows in the world. Let’s find out how transom windows work, what types are available, and some other interesting info.

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What Are Transom Windows and How Do They Work?

A “transom” is an architectural term for a horizontal crossbeam that goes above a door or window. Transom windows are designed to fit into the gap that the transom creates, effectively making another window above the door or window. Transom windows are sometimes called fanlites or transom lights because they let in light as well as air.

Transom windows were historically used to provide natural light and ventilation, where they could be operated by metal poles that opened and closed them. Today, transom windows are useful for creating extra light while not compromising on privacy, with ventilation as a low priority. In fact, most transom windows today are fixed and can’t be opened at all.

Transom windows are extremely flexible, coming in a wide range of shapes, sizes, and types. You can have a small, 2-inch transom window or a giant arched transom window as large as 6 feet tall.

Where Are Transom Windows Used?

Transom windows are most commonly seen above doors and windows on homes, but they’re also used above windows in buildings with tall ceilings, in bathrooms, garages, and sheds. Because they increase light and ventilation while preserving privacy, transom windows are a great addition to nearly any part of any building.

Transom windows on fancier homes and buildings are likely to be specifically decorative and fixed, meaning they don’t ventilate the building. Smaller transom windows on regular homes are typically more modest, with many bathroom or garage transom windows measuring just a foot high or smaller.

What Are the Different Types of Transom Windows?

There are four main types of transom windows that encompass virtually every conceivable style you could want. These are arched transom windows, fixed transom windows, shed-type transom windows, and bathroom transom windows.

window air conditioners on a building in new york
Image Credit: Tim Hüfner, Unsplash

Arched Transom Windows

Semicircular transom windows above rectangular windows can give the illusion of the entire window being arched. This type of transom window can be used over entryways, windows, and even gables.

Fixed Transom Window

As the name suggests, fixed transom windows are fixed in place and don’t open to provide ventilation. Because most buildings today are air conditioned, this is less of a problem than it would have been 100 years ago. Because of the fixed design, individual panes can be customized to fit a decorative pattern or effect.

Shed-Type Transom Windows

These are the long, narrow transom windows you often see in sheds, garages, and other temporary storage spaces. While they don’t allow in a lot of natural light, these transom windows are better at preserving privacy.

Bathroom Transom Windows

Bathroom transom windows are commonly used in large bathrooms with separate vanity areas, where they can provide extra ventilation when the room gets steamy. However, fixed transom windows in these areas can be shared with the attached bedroom, depending on the home design.

half bathroom
Image Credit: Anja, Pixabay

Advantages of Transom Windows

Natural Lighting

For large rooms, transom windows can be just the thing to increase the amount of light and make the space feel airier and brighter. For example, transom windows are great on top of French patio doors, which help enhance the interior from the outside.

Preserves Privacy

Transom windows add light and air, but they’re placed high up on walls to conserve privacy. This can make them a great addition to a large master bedroom, or any other area where you’d like light and privacy.


Transom windows vary in price depending on design complexity, but prices average $100–$250 per window piece. This can make them a very affordable way to accent your home and increase natural light.

Wide Variety of Styles

Transom windows can be fitted on square, rectangular, circular, or arched windows. The most common design is a rectangular or semi-circular pane delineated by markers at equal intervals. Pitched roofs have the extra option of a triangular or A-shaped transom window to give a unique look.

Fan-shaped windows that can be used for decoration and ventilation are popular, too. These windows typically swing out on hinges operated by metal rods and poles from the ground. However, fixed variations are available, too.

There are tons of more designs you can choose or customize yourself. For instance, there are paneled, symmetrical, decorative, and more styles of transom windows.

Energy Efficient

Combined with ceiling fans, functional transom windows can be an excellent alternative to running an air conditioner. Thanks to various solar coatings that can be applied to the glass, you can save even more money.

Disadvantages of Transom Windows

Despite their attractive design and other benefits, transom windows have some drawbacks that you should be aware of. Consider these along with the pros to make a more informed buying decision for your home.

Requires Frequent Cleaning

Transom windows need to be cleaned regularly with a clean, wet cloth. If you neglect to clean them for long periods of time, your window frame may become vulnerable to mold and termites. If left alone long enough, the entire window frame could rot or be eaten by termites.

Cleaning window using sprayer_Vladimir Miloserdov_Shutterstock
Image Credit: Vladimir Miloserdov, Shutterstock

Fixed Models Don’t Ventilate

Fixed transom windows are becoming very popular for their wide range of decorative patterns, but they lose the ventilation factor that makes transom windows so useful in the first place. You’ll probably find yourself running the air conditioner more often with fixed transom windows.

Can Make Smaller Spaces Hot

If the glass isn’t coated with a UV reflective coating, your window can let too much light in. For large spaces that can disperse heat well, it’s not much of an issue, but smaller spaces will become hot and stuffy.

Requires Maintenance

Over time, transom windows can develop cracks that will require filling. You can do this yourself with a caulking gun and stepladder or hire a professional to do it for you. Either way, this is an expected cost of transom windows over the course of many years.

FAQ: Transom Windows

  • Are transom windows out of style: No. Transom windows may not be used for ventilation as often as they once were, but they remain a relatively cheap way to instantly add light and a unique decorative style to a window or doorway. While transom windows were most popular for light and ventilation in the 17th to 18th centuries, they’re still used for that purpose in garages and sheds across the globe.
  • Do transom windows add value to your home: Yes, they will add value to your home. Although most transom windows are used for decorative purposes and to let light in, that’s plenty enough reason for them to boost your home’s value and curb appeal.
  • Where are the best places to use transom windows: Transom windows are best used on exterior doorways and large windows, but smaller variants can be used to great effect in bathrooms, sheds, and garages. Simply customize the type of window you want to match the space.

house divider Conclusion

Transom windows may not be as popular as they once were, but they’re still a great way to add light and decoration to any home or building. Ventilated transom windows are still popular for sheds and garages, so there’s no reason to believe the trend will die anytime soon.

Featured Image Credit: Africa Studio, Shutterstock


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