What is Tempered Glass?

Tempered glass is a type of safety glass designed to be significantly stronger than standard, annealed glass. In fact, it is approximately four times stronger and is engineered to reduce the risk of injury if broken. Because of these properties, tempered glass is required by law in areas where human safety is a concern, such as doors, shower enclosures, large windows, and commercial storefronts.

Unlike annealed glass, which can shatter into large, sharp, and dangerous pieces, tempered glass breaks into small, relatively harmless granules when it fails. This makes it a safer choice in homes and businesses where people could be exposed to glass breakage. Tempered glass must meet safety standards such as ANSI Z97.1, ensuring consistent performance and compliance with building codes.

How Tempered Glass is Made

Tempering involves a controlled heating and cooling process that strengthens the glass. After the glass is cut and cleaned, it is heated to approximately 1,100°F — the point at which glass becomes soft enough to reshape. The sheet is then rapidly cooled, or “quenched,” along the edges, creating a compression zone on the surface and a tension zone in the center. This balance of forces gives tempered glass its strength and durability.

The result is a glass that can withstand higher impacts, temperature fluctuations, and stress compared to standard glass, while providing enhanced safety for those nearby. In addition to its safety benefits, tempered glass is also widely used in areas where durability and resistance to breakage are important, such as commercial buildings, patio doors, and automotive applications.

At Two Panes Glazing, we provide tempered glass solutions for residential and commercial projects, ensuring safety, compliance, and peace of mind. By understanding how tempered glass works and why it matters, property owners can make informed choices for safer, stronger, and more reliable window and door systems.