Annealed vs. Tempered Glass For Homes

annealed glass We often receive calls and questions about using either annealed glass or tempered glass for window replacement in the home.

The difference has to do with the way the glass is made and what it’s used for.

Annealed vs. Tempered Glass

You can tell what type of glass you have by the way it breaks. Annealed glass breaks into large shards, and tempered glass breaks into tiny pieces. Tempered glass (also called safety glass), is four times stronger than annealed glass due to the way it is heated up then cooled down quickly in the manufacturing process. This process is what changes the way the glass breaks. It is able to resist higher temperatures (200-300 degrees), which would cause annealed glass to break. Tempered glass must be used in:

  • Doors
  • Windows that are less than two feet from a door
  • Windows that are less than two feet from the ground
  • Tabletop glass that you might set heavy or hot items on
  • Shower and tub enclosures
  • Glass used as walls or barriers

These photos clearly show the difference.

annealed vs tempered glass

Here is an explanation breakdown…

What Is Annealed Glass?

Annealed glass means that it has been slowly cooled, helping the glass to be stronger, more durable and less likely to break. When the glass is broken, it breaks into large shards of glass.

What Is Tempered (Toughened) Glass?

Tempered glass is made by putting the outer surfaces into compression and the inner surfaces into tension. This kind of compression makes the glass shatter into a multitude of tiny pieces upon impact.

So What Is The Difference Between Annealed & Tempered?

We are required to use tempered safety glass if a window is in a door, or if it’s located within 24 inches of a door or the floor.  Imagine a slamming door causing a window to break.  Tempered glass will break into thousands of tiny pieces that can’t cut you, while annealed glass will break into large shards, which can cut you.

Table glass is also tempered for safety, including patio table glass. Glass that is used as a covering for desks and end tables, etc., doesn’t have to be tempered.

Have a question about glass or need pricing? Call: 602-892-0202