Is the Glass in My Shower Door Tempered? How to Tell

If you're wondering whether the glass in your shower door is tempered, you're asking the right question. Tempered glass shower doors aren't optional -- they're required by building code in every state. But if your home is older or the shower was installed by a previous owner, there's a real chance the glass might not meet code.

Why Shower Glass Must Be Tempered

Building codes (ANSI Z97.1 and CPSC 16 CFR 1201) require that any glass in a hazardous location be safety glass. Showers and bathtubs qualify. Regular annealed glass breaks into large, jagged shards that can cause serious lacerations. In a wet, slippery shower, that's dangerous.

Tempered glass is four to five times stronger than regular glass. When it breaks, it shatters into small, roughly cube-shaped pieces instead of sharp daggers -- the same type of glass used in car side windows.

How to Check

Look for the etching. Tempered glass carries a permanent identification mark, usually etched into one corner. Look in all four corners -- it's typically small, about postage-stamp sized. The marking includes the manufacturer's name, safety standard (ANSI Z97.1 or CPSC 16 CFR 1201), and the word "tempered" or "TEMP."

Check the edges. If you can see an exposed edge, tempered glass has smooth, slightly rounded edges. Annealed glass has sharper, more unfinished edges.

No marking doesn't always mean it's not tempered -- older tempered glass sometimes had markings that faded or were hidden by the frame. But if you can't find any marking, treat it as a red flag.

What to Do If It's Not Tempered

Replace it. This isn't cosmetic -- it's a safety hazard. A glazier measures your existing door or panel and fabricates a tempered replacement. Tempered glass must be made to exact dimensions -- it can't be cut after tempering.

Cost typically runs $200 to $600 depending on size, thickness, and type (clear, frosted, low-iron).

When Shower Glass Needs Replacing

Beyond the tempered question: replace your shower glass if it has chips or cracks (compromised tempered glass can spontaneously shatter), if hardware is corroded and no longer holds the door securely, or if you're upgrading from framed to frameless. A small chip that seems harmless can weaken the entire panel.