What is a Window Sash?

Malcolm Tatum
Malcolm Tatum

An important part of traditional windows, the window sash is the moving section of the window. Depending on the design of the window proper, there may be one or more sashes that allow the space to be opened or closed according to the preferences of the occupant. With some window designs, the window is permanently fixed in place and cannot be opened at will.

Window sashes in older homes are typically constructed of wood and glass.
Window sashes in older homes are typically constructed of wood and glass.

The components that make up the standard window sash are very basic. This type of window is composed of a simple frame that is built to allow easy insertion into window casements. Within the frame, glass is inserted and sealed into place. The glass may be composed of a series of small panes that are connected with an interlocking framework and attached to the larger frame of the sash. For standard windows, the panes are often clear, although some designs call for tinted or stained glass components.

The sashes may be attached to the casement by a set of runners that help to hold them in place. The runners also include the tracks that allow the window to be moved up and down at will. At one time, the runner mechanism was operated with a series of ropes that were built into the casement. Later models used simply metal tracks to achieve the same purpose.

At one time, the window sash was constructed of wood and glass. Over time, metal frames were created for use in public buildings as well as new home construction. Considered to be durable and more energy efficient, the metal sashes were often constructed of lightweight aluminum. Their installation is very simple, and they are still a popular option for windows that are included on outdoor porch and patio doors.

While the metal sash continues to enjoy a great deal of popularity, many new homes are being constructed with the traditional wood sash. Providing a touch of tradition, the modern day wood sashes and casement options may be simple in design or include detailing that provides a customized touch.

Malcolm Tatum
Malcolm Tatum

After many years in the teleconferencing industry, Michael decided to embrace his passion for trivia, research, and writing by becoming a full-time freelance writer. Since then, he has contributed articles to a variety of print and online publications, including wiseGEEK, and his work has also appeared in poetry collections, devotional anthologies, and several newspapers. Malcolm’s other interests include collecting vinyl records, minor league baseball, and cycling.

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Discussion Comments


My wood windows, frames and sashes, started to rot after 12 years here in Wisconsin. I'm not a great fan either.


The life expectancy of wood windows on the Texas Gulf Coast is about 5-10 years. I strongly discourage the use of wood windows in this area. --Culture


Great point CleanTechie. I'm a building contractor and another asset of using wood over aluminum or uPVC is that a timber window has a life of anywhere from 60 to 120 years, where a uPVC window may only last 20 to 25 years. I always recommend wood windows to my clients. It's an energy wise choice and it increases the resale value of the home.


I am an environmentally conscious person and during a recent remodel of my home, I learned that wood sash windows are a more energy conscious material to choose than aluminum or uPVC windows. The reasons behind this are that aluminum windows take 20 to 25 more times the energy to make than ones made out of wood. Also, it requires more energy to salvage aluminum than wood.

The development of uPVC releases extremely contaminated chemicals into the atmosphere and the uPVC concoction uses 6 out of the 15 most hazardous chemicals listed by the EU, which are scheduled for priority elimination. It became very obvious to me that wood was the best choice for replacing my windows during the remodel. And let me tell you, I couldn't be happier.

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