How are glass blocks typically used in masonry siding?

Glass blocks are commonly used in masonry siding primarily for some windows. Their unique properties, such as translucency and thermal insulation, make them ideal for creating decorative and functional windows that allow light into a space while maintaining privacy. This application enhances the architectural appeal of a building while providing insulation and water resistance.

In contrast, other uses mentioned in the choices, such as entire walls or roofing, are less typical for glass blocks. While entire walls made of glass blocks can occur, they are most often utilized in a modular approach rather than being the main design feature for complete walls. Similarly, they are not suitable as base materials or roofing, as those applications require different structural and environmental attributes that glass blocks do not possess. Therefore, the use of glass blocks in masonry siding is best recognized for their inclusion in windows, blending practicality with aesthetic qualities.