What Is Tempered Glass?

Are you shopping for new replacement windows for your home near Dallas, Fort Worth, Texas? If so, you may be searching for info on tempered window glass to see what it is and why it’s essential. The fact is that some windows in your home are probably already tempered, and some new replacement windows will be too. Our article covers common tempered glass questions like pros/cons, costs, etc.

If you’re new to the world of replacement windows, two things: 1) Welcome! We’re glad you found us. And 2) You may realize there’s much to sort through and decide when getting new windows: style, material, color, type, price, glass, etc. We encourage you to do all the research on each option so you can feel confident when you decide.

What is tempered glass & why is it important?

Tempered glass is a type of safety glass made by heating an ordinary sheet of glass and heating it up to approximately 1200°F and then rapidly cooling it. Once the glass is heated, it is quickly cooled off with blasts of cold air. This cooling process forms compression along the surface and edges, making it four to five times stronger than regular glass. Tempered glass has increased strength and stability compared to standard annealed glass and breaks into small and non-sharp pieces, making it much safer for certain applications like home replacement windows. Replacing home windows with safety glass adds extra protection from breakage and makes them more shatterproof, ensuring greater safety if an accident occurs. Homeowners looking for energy efficiency may also want to consider tempered glass for replacement windows as its thickness helps retain warm air in winter and cool air out in summer months.


When do you need to use it in DFW?

Local building codes and commissions regulate the use of safety-tempered glass. Within DFW, there are a few scenarios that require safety glass. Avoiding these regulations can cause your project to fail an inspection and expose people living in your house to increased danger.

  • Glass in entry and patio doors must be tempered.
  • If your window is within 18″ of a door’s vertical edge when closed.
  • Windows that are less than 18″ from a walking surface, stairs, hallway, etc., and over nine square feet.
  • If your tub or shower glass is within 60″, you must have safety glass in the windows.


Thickness ranges for glass is

  • SSB 3/32″ (2mm) – normally used in picture frames.
  • 1/8″ (3mm) – used in storm windows, picture frames, end tables, insulated units, etc.
  • 3/16″ (5mm) – used for small tabletops, insulated units, small shelves, etc.
  • 1/4″ (6mm) – used in tabletops (as protective covering), insulated units, single-pane windows, shelves, framed shower doors, etc.
  • 5/16″ (8mm) – used in tabletops (as protective covering), lightweight shelves, framed shower doors, etc. It is not common in the US.
  • 3/8″ (10mm) – used in shower doors, tabletops, glass walls, glass partitions, handrails, door lights, etc.
  • 1/2″ (12mm) – used for shower doors, tabletops, glass walls, glass partitions, handrails, etc.
  • 5/8″ (15mm) – used for shower doors, glass walls, glass partitions, handrails, etc. It is not common in the US.
  • 3/4″ (19mm) – used for glass doors, mall fronts, tabletops, glass floors, etc.


How do you tell if your windows are tempered?

All glass manufacturers must identify tempered glass with a permanent mark. To determine if your glass is tempered, look for a symbol in the four corners of a window. If tempered, you will find an etched element in the glass.

Look for smooth edges to the glass for glass that is not already in a frame. Safety glass has sandblasted edges that are smooth. We don’t recommend running your fingers across the glass to see if it’s tempered in case it isn’t.


Is it more expensive than annealed glass?

Tempered glass is 50 – 70% more expensive than standard annealed glass, so it is typically only used where it’s required by code compliance. When getting a replacement window quote, ensure your rep identifies which windows have tempered glass. It’s something most reps should discuss during the initial site visit.


In closing

Tempered safety glass is a great way to protect your family from the dangers of broken glass. We hope we answered some of your questions about tempered safety glass, but please don’t hesitate to reach out if you have more questions. If you live in the DFW area, we would love to help you choose the right windows for your home. Give us a call at 214-399-9592.

Cover image provided by our door partner, ProVia.