How to Specify: Glass Block

Glass block comes with some aesthetic baggage, but there are a lot of contemporary designs that take the material’s storied legacy into the 21st century. If you’re considering using it, look to this article and the rest of the week’s glass block features to give you a sense of what’s possible and how to make the most of it.

The traditional glass block is not a solid block of glass, but is actually a square block with two glass faces and a mostly hollow interior. Those glass faces can be textured, patterned, frosted, colored or clear. Colored materials can also be added to the middle of the block to create more visual effects. Non-square models are available, too; rectangular blocks can be stacked like bricks, circular blocks can be embedded in a floor or ceiling and trapezoidal units create a shingle-like effect when stacked.

One of the most exciting developments in the area is the advent of the glass brick. Unlike the traditional hollow block, bricks are solid glass, usually in the shape of conventional terra-cotta bricks. The glass bricks are significantly more expensive than glass blocks, but they offer much more clarity and have a pretty dazzling effect.

Blocks can also be used to create floors and ceilings, and new models in development offer the promise of glass-block roofs. Embedded solar panels in blocks mean they can potentially be used as a power source.

If you’re thinking about designing with glass blocks, there are a few basics to be aware of. First, block walls are not to be used as structural walls. Glass-block walls are either curtain wall façades or interior partitions. They can self-support up to conventional floor-to-ceiling heights. The exact limits depend on the model. Larger-scale walls typically have some kind of external support like clips or embedded poles.

Glass-block walls can be relatively easily cleaned and are impact-resistant compared to basic stick-frame construction. Certain models are also made with a high insulating value, and with a range of opacities available, glass block walls can be a cost-effective way to bring in daylight. Although the blocks themselves aren’t operable, conventional windows can easily be embedded in block walls.

Block walls can turn corners either through special units or corner pieces, but they can also create round corners by using tapered joints in between blocks. All in all, the future through glass block looks, well, not bright exactly, but it has a pleasing sort of diffuse glow. Very nice.