Everything You Need to Know About Round Windows
By Cynthia Pigeon
Updated on December 5, 2025

The fenestra cochleae, more commonly known as a round window, has quite a distinctive flair, which adds a certain uniqueness to your home. However, its installation requires a certain dexterity and presents some particularities that should be considered before undertaking such a project.
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Here is a guide to installing a round window should you have been smitten by its quirky allure.
Sneak Peek at the Round Window

Source : Canva
Benefits
Given its one-a-kind aspect, the round window adds a unique touch to any decor as well as modern touch to any interior. Despite the inherent peculiarities associated with the installation process, one can be mounted just about anywhere.
Downsides
Since round windows are less conventional and very expensive to manufacture, they are much harder to find. Also, they are not available in all sizes; large round windows are particularly rare. They often have to be custom-made, which entails additional costs for the buyer.
Furthermore, round windows require the expertise of a skilled professional to be properly installed. Also, the installation of a round window on a newly built home can be challenging, especially if the shape of the window does not match the shape of the already existing frame on one of the walls of the house.
Various Materials and Openings
Note that round windows are available in the same materials as conventional windows, like aluminum, wood, and PVC. The window manufacturing process can also combine more than one material, allowing you to create a look that perfectly matches your interior design. Another option is to combine two types of openings on the same window, such as a tilt-open top half and a fixed bottom half.
Various Materials
Aluminum
While being quite sturdy, aluminum windows are also very easy to maintain and offer a more than adequate level of insulation. This material is also available in a wide range of colours and styles. Furthermore, with an impressive 40-year lifespan, waterproof, and rot-proof qualities, it is unfortunately rather expensive and tends to be easily damaged.
Wood
Wood blends well with a number of styles, and since it is typically treated with insecticides, water repellents, and fungicides, it can withstand the elements and the passage of time quite well. Wood has a rustic charm, which offers an aesthetic edge, while also having insulating and soundproofing qualities that are important. Nevertheless, wood requires some maintenance to preserve its original appeal.
PVC
This material is unaffected by mould and mildew and can withstand the elements while also having adequate insulating and soundproofing qualities. In addition, it requires minimal maintenance to keep its original lustre. It is flame retardant, available in a wide variety of patterns and finishes, and quite affordable. However, note that this material tends to discolour over time and is not particularly resilient to direct sunlight.
Types of Round Windows
When considering a round window, one often imagines a single model. However, the round window is characterized by its different openings. There is more than one variety available, including the:
Fixed Round Window: As it has no opening, it is particularly preferred in confined spaces such as a staircase or a corridor;
Vertical or Horizontal Pivot Round Window: This model opens sideways with a latch. It provides both ventilation and luminosity in a room;
Tilt-Only Round Window: It opens horizontally, with one section of the window tilting inwards and the other outwards. It also offers a great source of ventilation and pleasant lighting.
How big a round window can I get?
As previously mentioned, round windows are available in a rather limited range of sizes. In fact, the smallest windows available are between 15 cm and 25 cm, while the largest available are between 45 cm and 100 cm.
Generally, a fixed round window will be between 50 cm and 130 cm in diameter. The tilt-only round window will be limited to between 60 cm and 100 cm in diameter.
Fun Facts Pertaining to Round Windows
To bring light into the main room or a large area, a round window will not be sufficient in itself. In such a case, it should be installed for aesthetic rather than practical purposes. For small rooms, a round window can be a good light source.
Thus, a round window can be quite fitting in a kitchen, hallway, attic, and small bathroom. It can also serve as an interesting alternative to the traditional rectangular skylight.
Looking for more information regarding doors and windows? Check out our Door and Window Renovation Guide.
Round windows | What you need to know |
Benefits | Brings a certain uniqueness and a modern touchCan be installed anywhere on a home |
Downsides | Harder to findExpensiveNot available in numerous styles/sizesMust be installed by professionalsHarder to install on a newly built home |
Types of Openings | Fixed: No openingVertical (or horizontal) pivot: Lateral opening with a latchTilt-only: Horizontal opening |
Manufacturing Materials | Wood PVC Aluminum |
Available Dimensions | Smaller models: between 15 and 25 cmLarger models: between 45 and 100 cm |
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