Glass Block Windows: What to Know Before You Buy

Glass block has long been used in homes as a way to bring natural light and a feeling of openness to rooms yet maintain privacy. If you want privacy with an Art Deco flair, you can do no better than creating a curved glass block window on the front of your home, glass block in your foyer, or a glass block privacy screen in the bath.

Where to Use Glass Blocks

• Bathrooms
• Showers
• Front hallways
• Foyers
• Entrances
• Basements
• Bedrooms

Pros

Glass block is used in place of conventional clear glass exterior windows at the front of the house or on bathroom windows. It is also used as an interior non-load-bearing wall alongside foyers or in bathrooms.

Privacy is the top reason this material is installed. While lounging in the bathtub, you can get a reasonable amount of natural light filtering through an exterior glass block window, but it is impossible for anyone to look inside. Even someone who looks right up to the glass will only see vague images inside.

You can also use it for interior screens, such as in bathrooms where you might want to shield the toilet area from the rest of the bathroom. A conventional interior wall, built with studs and drywall, would only cast the toilet area in darkness.

Because glass block windows are constructed like a brick wall with mortar, they tend to be very solid and waterproof.

Cons

Glass block looks as solid and substantial as brick, but it does not have load-bearing capabilities. It cannot carry loads other than its load.

Homeowners may lose sight of this because glass block is installed much like a brick, with mortar. But you need to think of glass block just as you would a window: a fully self-supporting opening with fragile glass inside.

Not only that but for exterior walls, you will find that glass block is so heavy that it requires a sturdy base with a properly built sill and cripple studs running vertically below it.

Glass block windows can have small vents built into them, but it's impossible to open up the entire window.

Glass Block Window Trends

Glass block windows have come in and out of fashion throughout the 20th and 21st centuries.

Through glass blocks were developed in France in the 1930s, the best-known trend for glass blocks was in the 1940s. Film noir movies popularized the look of glass blocks. Areas that saw a lot of new, designer-driven building during the 1940s received glass blocks.

Much of Miami, Florida's South Beach was built up in the 1940s and this naturally included glass block. The glass block look was revived in the 1980s and 1990s, not just in Florida but in Los Angeles.

Glass blocks, also known as glass bricks, resurfaced around 2018-2019. New styles were developed, and not all glass brick looked had the traditional wavy-glass look anymore.

Using glass blocks in your home might date your home to the 1940s, 1980s, or to an entirely new decade of trend.

Glass Block Installation

Instead of building glass block windows and screens from scratch, pre-fabricated kits make the job easier. Installing glass block in your bathroom or even exterior can be a frustrating project because the material is so heavy and requires a precise opening (glass block cannot be cut).

But prefabricated glass block window units operate just like any other kind of replacement window. They have the glass blocks already installed in the unit, and the units have nailing flanges on the perimeter. These prefabricated glass block window units are then installed just like any other type of window.

If you are installing your own glass block, do not use regular brick mortar. You will need to use a premixed glass block mortar.

Regular brick mortar cannot be used because it has high water content, and this water gets pulled away by capillary action by the porous brick. Glass is not porous and so will not pull the water away. Glass block mortar is drier than brick mortar.

Glass Block Tips

• Glass block isn't always used for privacy. You can purchase clarity glass block, which is nearly as transparent as window glass.
• Because glass block is hollow inside, it does have some insulating properties, much like window glass IGUs (insulated glass units).
• Glass block windows are a security feature when used for exteriors. Glass block is very difficult to break through.