What is a Transom Window?

What is a Transom Window
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Reviewed by Bryan Baeumler

Transom windows, also known as transom lights, are a unique architectural feature that can significantly enhance the aesthetic appeal and functionality of your home. These horizontal windows can be installed above any door or window, allowing natural light to stream into living spaces while providing ventilation and airflow.

Key Takeaways

  • Transom windows are horizontal windows installed above doors or larger windows.
  • They provide natural light and ventilation to interior spaces.
  • Transom windows come in various styles, including semicircular, rectangular, and custom designs.
  • They can be installed as part of a new construction or retrofitted into existing structures.
  • Transom windows offer both functional and decorative benefits, adding architectural interest and character to a home.


Transom windows have been a popular architectural element for centuries, gracing homes with their elegant and practical design. Originally intended to improve ventilation and light distribution in buildings, these windows have evolved into a versatile feature that can complement various architectural styles, from traditional to modern.

In this comprehensive article, we will explore the world of transom windows, discussing their history, types, benefits, installation considerations, and design options. Whether you're a homeowner seeking to enhance your living space or an architect looking to incorporate unique elements into your projects, this guide will provide you with valuable insights into the fascinating realm of transom windows.

The History and Purpose of Transom Windows

The term “transom” derives from the Latin word “transenna,” meaning “across the beam.” A transom is a horizontal beam separating the top of a door or window from the wall.

Transom windows have their roots in ancient architectural practices, where they were used to regulate airflow and light in buildings. In the past, before the advent of modern heating and cooling systems, transom windows played a crucial role in ventilation.

Initially, these windows were designed to open inward, allowing hot air to escape through the top portion while drawing in cooler air from the bottom. This natural ventilation system helped maintain comfortable indoor temperatures and improved air circulation.


Over time, transom windows evolved from purely functional elements to decorative architectural features. Their unique shape and placement above doors and larger windows added visual interest and character to buildings, contributing to the overall aesthetic appeal.

Today, there are various transom window options available, inspired by historical designs, ranging from simple to custom designs.

Types of Transom Windows

Transom windows are always custom-made to fit the specific architectural design and dimensions of their door or window openings. While they come in a wide range of styles and designs, each transom window is crafted to offer its own unique charm and functionality, tailored to the homeowner's preferences and the building's character. Some of the most common window shapes include rectangular and semicircular.

Semicircular Transom Windows

Semicircular transom windows, often referred to as “fanlights,” are a classic and elegant choice. These arched windows are typically installed above exterior doors, adding a touch of sophistication and historic charm to a home’s facade.


Rectangular Transom Windows

Rectangular transom windows are a more modern and versatile option. They can be installed above interior doors or exterior doors and windows, providing a clean and sleek look that complements contemporary architectural styles. Rectangular or semicircular windows can add character and style to both interior and exterior doors.

transom window above a door

Popular Transom Window Styles and Their Characteristics

Style Description Best Suited For
Semicircular (Fanlights) Arched windows with a semicircular shape, often installed above exterior doors or larger windows. Traditional, historic, or classical architectural styles. Adds elegance and charm.
Rectangular Simple and clean rectangular shape, available in various sizes and proportions. Modern, contemporary, or minimalist architectural designs. Offers a sleek and versatile look.
Curved Transom windows with gentle curves or arched shapes, creating a softer and more organic appearance. Adding visual interest and a unique focal point to any architectural style.
Divided Light Transom windows with grids or patterns, mimicking the appearance of smaller, divided light sections. Enhancing the traditional or historic character of a home, particularly in period-style architecture.
Stained Glass Transom windows featuring stained or decorative glass designs, often incorporating intricate patterns or colours. Adding artistic flair and a distinctive visual element to the interior or exterior of a home.


Transom windows designed and crafted to meet specific size, shape, or style requirements, allowing for unique and personalized solutions. Homeowners seeking a one-of-a-kind look or architects designing for a specific architectural vision.

Pros and Cons of Transom Windows

Pros Cons
  • Increased natural light penetration into interior spaces
  • Improved ventilation and air circulation
  • Architectural interest and visual appeal
  • Can contribute to energy efficiency by reducing reliance on artificial lighting
  • Enhance curb appeal and overall aesthetic of a home's exterior
  • Versatile design options to complement various architectural styles
  • Allow for unique design elements like stained glass or decorative patterns
  • Provide a connection between interior and exterior spaces
  • Add historic charm and character to older homes
  • Potential privacy concerns if not properly covered or treated
  • Difficulty in reaching and cleaning the exterior of high transom windows
  • Potential for drafts or air leaks if not properly installed or sealed
  • May require structural modifications or reinforcement during installation
  • Potential for water infiltration if not properly flashed and sealed
  • Can be more expensive than standard windows, especially for custom or specialty designs
  • Limitations on window covering options due to the window's placement and size
  • May not be suitable for all climates or regions due to potential heat gain or loss
  • Potential noise transfer from outside, depending on the glass type and installation

Installing Transom Windows

Transom windows can be installed as part of a new construction project or retrofitted into existing structures. Transom windows can be located above front doors, windows, and interior doors, including French door patio windows and even high on basement walls in historical homes.

Here are some considerations for installing transom windows:

New Construction

When building a new home or addition, transom windows can be seamlessly integrated into the design. This approach allows for proper framing and structural support, ensuring a secure and well-fitted installation.

Existing Structures

If you're considering adding transom windows to an existing home, it's essential to consult with a professional contractor or architect. They can assess the structural integrity of the walls and ensure that the installation process does not compromise the building's stability.

Professional Installation

While DIY enthusiasts may be tempted to tackle the installation themselves, it's generally recommended to hire a licensed contractor or professional window installer. They have the necessary expertise and tools to ensure a proper and safe installation, minimizing the risk of potential issues or structural damage.

Design Options and Considerations

Transom windows offer a wide range of design possibilities, allowing homeowners and architects to create unique and personalized looks.

The resurgence of modern transom windows highlights their decorative and architectural value in complementing today's trends. Here are some design options and considerations:

Glass Types

Transom windows can be crafted with various glass types, including clear, frosted, stained, or decorative glass. Clear glass maximizes natural light transmission, while frosted or stained glass options can provide privacy or add artistic flair to the design.

Window Frames

The frame material and colour of transom windows can significantly impact the overall aesthetic. Popular options include wood, vinyl, aluminum, and fibreglass frames in a variety of finishes, such as white, black, or wood-toned colours.

Window Grids or Patterns

For a more traditional look, transom windows can incorporate window grids or patterns, mimicking the appearance of smaller, divided light sections. This design element can add visual interest and complement the architectural style of the home.

Window Coverings

While transom windows are primarily intended to allow natural light and ventilation, window coverings can be added for privacy or light control. Options include curtains, blinds, or shades specifically designed for transom windows.

Exterior Cladding and Trim

For exterior transom windows, the surrounding cladding and trim can play a crucial role in the overall aesthetic. Choosing complementary materials and colours can create a cohesive and visually appealing look that blends seamlessly with the home's exterior design.


While some may consider transom windows outdated, many homeowners still appreciate their historic charm and curb appeal.

At the end of the day, transom windows are a versatile and visually appealing architectural element that can enhance the functionality and aesthetic appeal of any home. From providing natural light and ventilation to adding architectural interest and character, these horizontal windows offer a range of benefits for homeowners and designers alike.

Whether you're building a new home or retrofitting an existing structure, incorporating transom windows can be a fantastic way to create a unique and inviting living space. With their rich history, diverse styles, and practical advantages, transom windows continue to captivate homeowners and architects, leaving a lasting impression on the built environment.

As you embark on your journey to explore transom windows, remember to consult with professional contractors or architects to ensure proper installation and adherence to building codes and regulations.

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Frequently Asked Questions

Can transom windows be opened for ventilation?

Yes, many transom windows are designed to be operable, allowing for ventilation and airflow when desired. However, some transom windows may be fixed and non-operable, primarily serving a decorative purpose. Interior transom windows can help circulate air throughout the home, and can be opened to allow airflow.

Are transom windows energy-efficient?

Transom windows can contribute to energy efficiency by allowing natural light to penetrate deeper into the living spaces, reducing the need for artificial lighting during daylight hours. However, proper insulation and energy-efficient glass options are essential to maximize energy savings.

Can transom windows be added to existing doors or windows?

Yes, it is possible to retrofit transom windows into existing doors or windows, but it may require structural modifications and professional installation to ensure proper support and integration.

Are transom windows suitable for all architectural styles?

Transom windows can complement various architectural styles, from traditional to modern. Their versatile design and range of styles make them adaptable to different aesthetic preferences and building designs.

Do transom windows require special maintenance or cleaning?

Like any window, transom windows may require periodic cleaning and maintenance to ensure optimal functionality and appearance. Regular cleaning and inspection can help identify potential issues, such as drafts or seal failures, allowing for timely repairs or replacements.

Julia Gurevich
Julia Gurevich

Julia Gurevich is a versatile content writer with a passion for delivering captivating narratives through a diverse and attentive approach. Her eye for detail helps her craft content that resonates with audiences across varied home improvement industries, capturing the perfect balance between information and entertainment. As a content coordinator, Julia takes pride in delivering content that leaves a lasting impact through her ability to navigate seamless content strategies and collaborative projects between teams. In her free time, she enjoys exploring Toronto’s cultural landscape, visiting local parks, and getting to know members of the community through events and activities.

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Reviewed by Bryan Baeumler

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