Glass Blocks Information

Glass blocksGlass blocks or bricks are architectural products that allow light to pass through, while also providing a level of privacy or obscuration. Glass blocks are typically square in shape and can have a variety of surface treatments that affect their transparency. Architectural glass blocks are solid or hollow glass components used in the construction of walls or features such as:

  • bathroom showers
  • separators in commercial offices
  • for decorative detail

Some glass blocks are manufactured with special characteristics, including resistance to fire and hurricanes.


Architectural glass blocks were developed in the 1900s for use in factory buildings. The transparent blocks let in more natural light, while also providing privacy, minimizing noise, and thermally insulating the space. Hollow glass blocks are used in all kinds of applications including:

  • residential buildings
  • commercial buildings
  • industrial buildings
  • municipal buildings

Some are even used in transit applications such as subway terminals, airports, and parking garages. The glass surface may be clear, etched, patterned, shaped, or colored to produce a desired aesthetic effect. Some glass blocks are shaped as finishing components for the corners, tops, and ends of walls. Decorative hollow glass blocks are designed with an opening that can be sealed with a cap, allowing a user to insert an object into the glass block and seal it closed.


Glass blocks are often assembled like bricks with a grout or sealant. Some blocks come with assembly systems that provide wall anchors and vertical and horizontal spacers to precisely align the blocks. The blocks are spaced accurately and consistently using the spacers and then bonded together with silicone. The joints are finished with tile grout or mortar. Glass blocks used in prisons and detention centers, police departments, and other high-risk locations are often set in steel frames for added strength and security.


Other types of glass blocks include foamed blocks that are used in industrial and commercial buildings to provide thermal and sound insulation. Foamed glass blocks are manufactured in molds, packed with crushed or granulated glass, and mixed with a chemical agent such as carbon or limestone. The blocks are heated until the glass begins to soften; then the carbon or limestone gives off a gas that is trapped in the softened glass, giving the blocks a cellular structure when they cool. Unlike architectural glass, foamed glass is opaque. Foamed glass blocks are also impermeable, waterproof, resistant to chemicals, and non-combustible. They may also be cut, shaped, or machined into a variety of shapes and sizes. Because foamed glass blocks are manufactured from crushed glass and carbon, they are resistant to molds, fungi, and other microorganisms. This makes them suitable for use in both exterior and interior floors, walls, and roofs.

Related Information

IEEE Spectrum—Nanostructured Glass Can Switch Between Blocking Heat and Blocking Light

Image credit:

Ramiltibayan / CC BY-SA 4.0


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