What is a Transom Window?

Thinking of adding one of these above-the-door-frame windows to your next project? Learn more today.

To understand what a transom window is, you first need to know what a transom itself is: It’s a beam that separates the top of a door or window from the wall.

So, a transom window typically appears above a door frame and provides additional natural light, and sometimes fresh air, into an entryway or room.

A few more definitions to watch out for: Transom windows can also be called transom lights (or lites, as these glass panes are sometimes referred to). Lastly, a fanlight is a type of transom window. It’s referred to as such due to its semi-circular shape, like (as you’d guess) a fan.

What is the Function of a Transom Window? 

Builders historically installed transom windows in homes to allow air to flow through the house with the doors closed. They appeared predominantly in row houses that didn’t have many windows.

Today, transom windows are used most often to add natural light to homes. They’re primarily used for architectural and light-capturing appeal and do not open, but this is not always the case.

Transom Windows and Front Entryways 

Transom windows frequently appear in entryways to add more natural light to the home. They also complement contemporary front door styles that feature nostalgic nods and charm. Transom windows also often appear with vertical side windows, known as sidelites, that frame front door designs.

As far as architectural styles, Georgian and Colonial Revival homes utilize transom windows most frequently, often including arched transom windows with grilles on these traditional-styled homes and their entryways.

Transom Windows and Interior Doors

Transom windows do appear in interior spaces, but they’re not as popular as those paired with entry doors. A transom window above an interior door is a benefit to spaces where natural light can shine through. Some common uses include bringing light to bathrooms or above patio doors.

Can a Transom Window be Replaced? 

Yes, transom windows can be replaced. Transom windows included in an entry door frame need extra consideration from those not included in the frame. If the glass has broken on a transom window, the entire sash can need replacement in some instances.

Signs that a Transom Window Needs Replacement

Leaks and water damage: If you notice water stains or signs of rot on wood windows, it’s time to think about replacing a transom window. Leaky windows can lead to a host of other problems with your home. Moisture can lead to mold and compromise the integrity of your windows.
Rot: Water issues can lead to wood rot with wood windows. If left untreated, your windows can start to fail. It’s important to replace transom windows that show signs of wood rot.
Broken glass: In most cases, broken glass in a transom window can mean a replacement need. Due to the construction of some transom windows, repairing broken glass can mean replacing the entire window.
Window drafts: Drafty windows can make your home less energy efficient and feel colder in cooler months. A transom window can feel drafty for a variety of reasons. In some cases, the best option is to replace a drafty transom window.
Condensation and/or fog between window panes: Condensation on windows can signal different things. If you notice condensation between glass panes in a transom window, it can mean the seal has failed. A broken window seal compromises the energy efficiency of the window and can lead to transom window replacement.

Transom Window Types and Styles

As mentioned, transom windows typically appear above front doors, but they can also appear in bathrooms, inside homes, and above garage or patio doors.

Transom windows usually appear rectangular in shape, though they can come as arch and radius tops. Marvin offers TruStile front doors with a multitude of transom options.

Here are some of the most common transom types:

Direct-Set Transoms

These windows are set directly into the transom frame. Direct-set transom windows cannot be opened, serve primarily as an additional way to add natural light to a home, and add decorative appeal. Also known as fixed transoms, these windows can enhance a home’s curb appeal by creating the appearance of a bigger entry way. Rectangular transom windows can fit in well with Craftsman homes, while curved transom windows are a natural fit with Victorian homes.

In-Sash Square Transoms

In-sash square transoms differ from direct-set transom windows because they get glazed into a separate sash, which gets secured to a frame. The result? These windows can open and close (if designed that way). Though the popularity of operable transom windows ebbs and flows, it can be a good option for homeowners looking to add airflow to a home.

Arch- and Radius-Top Transoms

TruStile offers arch-top transom windows that feature a slight curve, as well as radius-top transom windows that have more of a semi-circle curve. Arch-top and radius-top transom windows fit well in homes with more traditional architectural styles, like Gothic.

Frequently Asked Questions

Do transom windows open?

Yes, transom windows can open, but most transom windows installed today do not open, instead serving design and natural light purposes.  

What is the average cost of a transom window?

The cost of a transom window depends on the size of the window and options selected. Bigger transom windows can increase cost, while options like window grids and the type of window glass chosen can impact costs as well.  

What are the advantages of transom windows?

Transom windows fit in nicely in tall entryways because they can fill in otherwise unused space above a door, providing more natural light as well as design appeal.

Along those lines, transom windows can add elegance or historic notes to a home, especially curved units with specific architectural styles.

Lastly, transom windows can help with energy efficiency. How? Because they can add light to a space, meaning less of a need to turn lights on in a room.

What are the disadvantages of transom windows?

Since transom windows sit above a door, cleaning them can be a little tougher than other windows.

Also, transom windows might not go well in certain entryways. They require sufficient space above your door. Your project partners, will be able to help you decide if a transom window is right for your home.

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A modern bedroom, featuring an Ultimate Sliding door with a transom window above it.