What are Glass Block Windows?

What are Glass Block Windows?

Glass block windows were invented in the early 20th century↗. This new type of window was designed to allow more light into factories and manufacturing plants. They also gained popularity in residential use but that wasn't until the 1950s. Their ability to provide ample lighting while protecting privacy made them a popular choice for bathroom windows. 

To this day, bathrooms, basements and industrial spaces are the most common places to see glass block windows. And while some might consider these windows to be outdated, glass blocks still have a place in many homes. In this post, we'll discuss this style further and provide a list of places to shop for glass block windows.

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What are Glass Block Windows?

Glass block windows (sometimes referred to as glass bricks) are small, square-shaped windows that are typically installed in a grid-like pattern. Each block window is usually made with two layers of textured glass for privacy, and a cavity filled with air or argon gas for insulation. 

This window style is most often seen in older homes and is particularly common in bathrooms and basements. These windows also look right at home in spaces with an industrial aesthetic, such as renovated lofts and other reclaimed buildings. 

Pros and Cons of Glass Block Windows

Favored by some architects for their benefits and shunned by others for their appearance, glass block windows have advantages as well as some potential disadvantages. In certain homes—and in certain parts of your home—they could be ideal. 

Pro: Energy Efficient

Like most windows with double panes, glass blocks provide good insulation, which makes them an energy-efficient choice. Look for modern glass block windows with pressure controlled argon gas inside the block for reduced heat transmittance and better insulation.

Pro: Lighting and Privacy

The chief advantage of glass block windows is that their textured surface offers privacy without sacrificing light. Today, frosted and decorative glass also serves this purpose, but when glass block windows were invented over a century ago, these alternatives were not readily available.

Pro: Secure and Watertight

Glass block windows are usually sealed in with the mortar of the wall, which makes them very airtight and resistant to leaks. They're also quite difficult to break, making them good for security. Glass block windows can be made tornado-resistant and even bulletproof. 

Con: Outdated Aesthetic

While there are those who like the look of glass blocks, these windows are generally considered to be old-fashioned and somewhat outdated. That being said, there are certain architectural styles where they shine.

Con: Lack of Ventilation

Because glass block windows don't open or close, they don't provide any ventilation. For this reason, their use is limited. In basements, some homeowners choose to include a small hopper window or vent in a glass block window to provide some airflow. 

Con: Need for Support

Glass block windows are very heavy, and they often need structural support. Be sure to only have glass block windows installed by a qualified window professional. 

Who Sells Glass Block Windows?

Glass block windows are made by countless local and nationwide window companies all over the US. Some of the top glass block window brands include:

If you're interested in glass block windows check out the companies above to learn how to order this window style for your home. To learn more about other window styles see the related articles linked below or explore our product catalog.


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