Do Your Windows Have Safety Glass? How to Check

If you have windows in hazardous locations, you might wonder whether they have proper safety glazing. According to the CPSC, safety glass must be permanently marked—but those markings aren't always obvious.

Finding the Safety Glass Marking

According to ANSI Z97.1 standards, safety glazing must display:

Location: Usually in a corner of the glass

Information required:

• Manufacturer or fabricator identification
• Safety standard reference (ANSI Z97.1 and/or CPSC 16 CFR 1201)
• Type of safety glazing (tempered, laminated, etc.)

Marking methods:

• Etched into glass surface
• Sandblasted
• Ceramic frit (fired into glass)

What the Markings Look Like

Typical examples:

```
ABC GLASS CO.
TEMPERED
ANSI Z97.1
CPSC 16 CFR 1201 II
```

The marking is permanent and cannot be removed without damaging the glass.

If You Can't Find a Marking

According to CPSC, absence of marking may indicate:

1. Glass predates requirements: Pre-1977 glass may not be marked
2. Non-compliant glass: Glass wasn't rated when installed
3. Marking is hidden: Check all corners, including behind frame
4. Marking has faded: Some older markings are hard to read

Testing Methods

If markings aren't visible:

Polarized light test: Tempered glass shows stress patterns when viewed through polarized lenses (like sunglasses). Hold polarized glasses at an angle to window.

Sound test: Tempered glass has a different resonance than annealed—a sharper ping when tapped.

Note: These aren't definitive—professional inspection may be needed for critical applications.

What If Windows Aren't Up to Code?

According to CPSC guidance, non-conforming glass in hazardous locations presents risk. Options:

1. Apply safety film: Retrofit film can provide some protection (though not full code compliance)
2. Replace glass only: Replace IGU with properly rated glass in existing frame
3. Replace window: Full replacement with code-compliant unit

The Bottom Line

Check your windows in hazardous locations for safety glass markings. According to CPSC, if you can't confirm safety glazing in required locations—especially bathrooms and near doors—consider professional inspection or replacement.

*For complete safety glass information, see: [Safety Glass Requirements](/guides/safety-glass-requirements)*