Glazing - Types

Glazing and framing are often the most thermally vulnerable parts of a building envelope. However, when properly managed, they offer exceptional design flexibility and performance benefits—from maximising daylight and views to enhancing thermal comfort and acoustic control.

These systems are incredibly diverse, serving functions that range from safety and noise reduction to energy efficiency and visual clarity. Understanding the types of glazing available is essential for selecting the right solution for your project's performance and design goals.

Glazing Types and Their Characteristics

Annealed Glazing

The most commonly used architectural glass, annealed glazing is not heat-treated, which results in excellent surface flatness and optical clarity. However, it breaks into sharp, hazardous shards, making it less suitable where safety is a concern.

Heat-Strengthened Glazing

This type of glazing undergoes controlled heating and cooling, producing at least twice the strength of annealed glass. It offers improved resistance to wind and thermal stress, though it may have some distortion. Like annealed glass, it breaks into large shards.

Toughened (Fully Tempered) Glazing

Toughened glazing is around four times stronger than annealed glass and is engineered to break into small, less dangerous fragments, making it suitable for safety applications. The heat treatment can cause slight visual distortion but greatly enhances durability and impact resistance.

Laminated Glazing

Laminated glass consists of two or more layers bonded with a plastic interlayer. In the event of breakage, the interlayer holds the shards in place, preventing fall-out. It also offers UV protection, acoustic dampening, and enhanced safety, making it ideal for skylights, sound-sensitive areas, and protective installations like blast or bullet-resistant glazing.

Low-Iron Glazing

Made with reduced iron content, low-iron glass eliminates the greenish-blue tint common in standard clear glass. This makes it ideal for applications where visual clarity is critical, such as storefronts, museums, and aquariums. It also offers higher light transmittance and lower solar reflectance.

Double-Glazed Units

Double glazing features two panes of glass separated by a sealed air space, usually containing a desiccant to prevent condensation. This configuration significantly improves thermal and acoustic performance compared to single glazing. The lifespan and effectiveness depend on the quality of the sealants and spacer materials.

Triple-Glazed Units

Triple glazing builds on the same principles as double glazing but includes a third pane, offering even better thermal insulation and sound control. It’s commonly used in high-performance or passive building designs where maximum energy efficiency is required.