What Are Transom Windows? (2024)

By Jesus Sanchez Garcia Updated February 6, 2024

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Transom windows, also called transom lights, have been around since the 14th century. They’re named for the horizontal beam they sit on top of, called a transom, which separates the top of a door or window from the wall above. Though transom windows are typically more decorative than functional, they’ve been making a comeback because of their historic charm. Read on to learn about their function, cost, and available styles.

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Window Replacement Cost

Replacement windows on average range from $300 to $1,200.

Windows with fixed top sash and bottom sash that slides up, sash divided by white grilles a surrounded by white elegant frame horizontal white vinyl siding on a new construction residence
Single-Hung Windows

Single-hung windows on average cost $150 to $400 per window.

Low angle view of a plastic PVC window with a white metal frame in a modern house, showing an open window with blurred green trees and a clear sky outside.
Energy Efficient Upgrades

Double-pane installation typically ranges from $450 to $1,000 per window.


What Are Transom Windows?

You’ve likely seen many transom windows but may not have paid them much notice. Transom windows are the rectangular or semicircular windows above a door or other window. Some are designed to open, but most are for appearance only. Transom windows can make doors and windows feel larger and more grand, calling back to the regalness of older homes. 

Transom Windows Function

Before electricity and air conditioning, transom windows served multiple purposes. They let additional natural light into a room at a height that didn’t enable others to look in. They also opened via metal hinges, providing airflow.

Exterior transom windows were located on front doors to allow air in from outside. Interior transom windows provided airflow throughout the home. Modern transom windows typically don’t open and are primarily used for decorative purposes.

Transom Window Styles

There are two main types of transom windows: rectangular and semicircular. Rectangular transom windows are often installed above doors and can be single or multipaned. They extend across the width of the door or to the width of the door and the side windows around it, also known as sidelights. Semicircular transom windows, also called fanlights, are popular above both doors and windows. They can be single or multipaned and even domed. 

Material options for transom windows vary. You can choose from stained, textured, frosted, or clear glass in addition to wood, aluminum, fiberglass, or vinyl window frames. You can also get transom windows that are fixed or those that open. There are even options that include moisture sensors and close automatically when it rains.

Transom Window Installation

If your home doesn’t already have transom windows or you want to change the ones you have, a licensed contractor can install new ones. It’s easiest to install transom windows during construction, but you can still add them to existing doors and windows. 

You can opt for a transom window by itself, which requires a contractor to cut a hole above a door or window. Exterior door and window installation will likely require installing an entire door or window system for proper weather protection, pest control, and energy efficiency. These systems are sold and installed as one unit, so there’s less chance of poor sealing. 

The door or window height, ceiling height, location of the door or window, and whether the transom window will bear weight all affect how it will be installed. The standard process to install a transom window is to remove the drywall or exterior cladding above the window or door, then remove a section of wall studs to reframe that section. A contractor will set the window in place and add new drywall around it. For exterior walls, cladding is replaced. The window trim is then installed.

Transom Window Cost

Transom window cost varies by style. Transom windows that have traditional glass, are inoperable, and are framed with wood, vinyl, or aluminum start around $100. Stained, frosted, or textured glass increases the price, as does shaped glass. Expect to pay more if the transom window you want is particularly large or if you’re installing it on an exterior door or window. It’s not uncommon for a full unit that includes a transom window, door, and sidelights in one sealed system to cost thousands. 

If the transom style you want doesn’t suit your existing window, you can install a matching replacement window

Should You Install Transom Windows in Your Home?

As long as the wall you want to install a transom window on is structurally sound and you have enough space over the door or window, a contractor should easily be able to install a transom window. You should always hire a vetted and licensed contractor to perform this job. Attempting to do it yourself could lead to structural issues and problems with moisture, pests, and energy inefficiencies.

Our Recommendation

Both old and modern transom windows are a beautiful addition to exterior and interior doors. Though transom windows dipped in popularity during the early 2000s, homeowners are now bringing them back for their nostalgia and charm. If you have a renovated historic property and want to restore old architectural details, transom windows are a quick way to make it feel as regal as it did in its heyday.

We recommend gathering design inspiration online or by strolling through your local historic district to see what shapes and styles you like. Then, work with a qualified designer and contractor to ensure a great end result. See our list of best window brands to find transom window options.

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Transom Windows FAQ

What is the purpose of a transom window?

Transom windows add style and allow in more natural light. They also increase airflow if the window is operational.

What is considered a transom window?

A transom window is any widow that sits on top of the beam, or transom, over a door or other window.

Can transom windows be opened?

Yes, transom windows can be opened via metal hinges if they’re designed to be operable. 

Are transom windows outdated?

Transom windows are a personal design choice. Some people may think they’re outdated, but many homeowners like their historic charm and curb appeal.