What is the Difference Between a Casement Window and a Transom Window?

Casement vs Transom WindowThe difference between a casement window and a transom window can be very important to understand when shopping for a home, designing a new home, or thinking about a home improvement project. Before making any decisions, make sure you understand the different uses of transom and casement windows.

Casement Window

Casement windows open into the room, or more commonly, outwards much like a door does. Casement windows can have the hinged swinging parts (the sash) mounted on the sides, functioning similarly to a door; if both sides are equipped with hinges, it opens and closes exactly like a pair of double doors. A variant on the casement window has the hinged sash attached at the top. This type of window is sometimes called an awning window. The hinged part swings upward when opening, resulting in the pane of glass acting much like an awning over the opening.

Some casement windows are opened using a hand-cranking mechanism. Others use projection friction stays and espagnolette locking. Casement windows are the most common design of window in the UK and parts of Europe. They tend to be much less common in the United States, according to The Chicago Tribune.

Transom Window

A transom window is usually mounted above a door. Sometimes they are also inserted above other windows. Architects like to use them when a complicated structure such as a fancy door or window needs to transition into the next transverse element. The transom window can be designed in practically any shape, so it can easily be used as a transitional or ornamental element for practically any door or window design.

Traditionally, transom windows are fan-shaped, but of course they can be created in any shape. They are highly functional in that they increase the amount of light entering a room. When mounted over a door, they may be the only source of natural light in that room. When mounted over a window, they expand the wall area composed of window, according to Houzz.

Many transom windows are fixed and cannot be opened. However, some are designed to pivot open in exactly the same way that casement windows do. Adding transoms that can be opened is an excellent way to increase the ventilation into a room. For example, installing a transom awning window in a bathroom can allow fresh air and light into the room without revealing the interior of the bathroom to prying outside eyes.

Different Uses

Although at first glance a transom window that opens like a casement window is the same type of window, the difference between a casement window and a transom window is in how they are mounted. Casement windows are usually the primary window in a room, mounted at eye level. Transom windows are always auxiliary windows- mounted above another window or above a door. Transom windows don’t always have to be placed in exterior walls, either. Transom windows placed above interior doors can provide light to rooms with limited exterior window space.

Related Resource: Thermal-Paned Windows

Now that you understand the functional difference between a casement window and a transom window you can proceed with your home improvement project with confidence.