Checking for Tempered Glass in Doors: Is Your Home Up to Code?
Too Long; Didn't Read
- All glass in and near doors must be safety glass (tempered or laminated) per the Ontario Building Code, Section 9.6.1.
- Look for the etched stamp. Tempered glass has a small manufacturer's logo etched into one corner — usually with "TEMPERED" or "T" and a CSA or ANSI code.
- No stamp doesn't always mean not tempered. The stamp can be hidden behind the frame or worn off. Use the polarized light test as a backup.
- If your door glass isn't tempered, replace it. A body impact against annealed door glass creates large, razor-sharp shards that cause serious lacerations.
- Replacement cost: $150-$400 per door lite, depending on size and glass spec.
Answer First: Look for a small etched stamp in the corner of the glass — it'll say "TEMPERED" or show a "T" with a manufacturer code. If you find it, your door glass meets code. If there's no stamp, put on polarized sunglasses and check for rainbow stress patterns at an angle. No stamp and no stress patterns means the glass is likely annealed (non-safety) and should be replaced. Cost: $150-$400 per door lite.
Why Door Glass Must Be Tempered
When someone walks into a glass door — a child running, someone carrying groceries, a slip on a wet floor — the impact can shatter the glass. The type of glass determines whether that's a mess or a medical emergency.
Annealed glass (regular glass) breaks into large, jagged shards with razor-sharp edges. These shards cause deep lacerations, severed tendons, and in severe cases, fatal injuries. Emergency rooms across Ontario treat hundreds of glass-related injuries from doors every year.
Tempered glass breaks into small, roughly cubic pieces with blunt edges — like car side windows. The pieces scatter but rarely cause serious cuts. This is why every building code in North America requires tempered or laminated glass in doors and near-door locations.
Laminated glass cracks but holds together on the PVB interlayer. The glass stays in the frame. This is equally safe and preferred for security applications.
What the Ontario Building Code Says
OBC Section 9.6.1 mandates safety glazing (tempered, laminated, or wired glass meeting CSA A440 or ANSI Z97.1) in these locations:
| Location | Requirement |
|---|---|
| All glass in doors | Must be safety glass — no exceptions |
| Sidelites within 300mm (12") of a door edge | Must be safety glass |
| Glass within 500mm (20") of the floor | Must be safety glass |
| Shower and bathtub enclosures | Must be safety glass |
| Glass adjacent to stairways and ramps | Must be safety glass where people could fall into it |
| Sliding patio doors | Must be safety glass (entire panel) |
The 300mm sidelight rule catches a lot of older Toronto homes. Many front entries have decorative sidelite panels flanking the door that were installed with annealed glass before the code was updated. If the glass edge is within 300mm of the door frame, it needs to be tempered or laminated.
How to Check: The Stamp
Every piece of tempered glass manufactured to North American standards carries a permanent identification mark. It's etched or sandblasted into the glass during production — before tempering, so it becomes permanent.
What the stamp looks like:
- Size: About the size of a postage stamp
- Location: Usually in the bottom corner of the glass, closest to the hinge side of the door
- Content: Manufacturer name or logo, the word "TEMPERED" (or just "T"), and a standards reference (ANSI Z97.1, CPSC 16 CFR 1201, or CSA A440)
Finding a hidden stamp:
The stamp may be:
- Behind the frame or gasket. On some door lites, the glass sits deep in a channel and the stamp corner is covered by the frame. You won't see it without removing the glass — which isn't practical for a quick check.
- On the exterior side. Check both sides of the glass.
- Faded or worn. Stamps on older glass (20+ years) can be difficult to read, especially if the glass has been cleaned with abrasive products.
- Missing entirely. Some tempered glass, particularly from smaller manufacturers or imported glass, may not carry a visible stamp. This doesn't definitively mean it's annealed — but it means you need a second test.
How to Check: The Polarized Light Test
This is the backup test when no stamp is visible.
What you need: Polarized sunglasses (not just tinted — they must be polarized). Most quality sunglasses sold in the last 10 years are polarized.
How it works:
- Put on the polarized sunglasses.
- Look at the door glass at a slight angle (not straight on — about 20-30 degrees off perpendicular).
- Look for faint rainbow-colored stress patterns — iridescent spots, lines, or a grid pattern across the glass surface.
These patterns are caused by the internal stress layer that makes tempered glass strong. The tempering process creates regions of compression and tension in the glass, and polarized light makes these regions visible as color shifts.
Annealed glass shows none of these patterns. It appears uniformly transparent through polarized lenses.
Caveat: The test works best in bright, indirect daylight. It's harder to see the stress patterns on overcast days or through tinted glass.
Common Locations Where Tempered Glass Is Missing
In our experience across hundreds of GTA homes, these are the spots where we most often find annealed glass that should be tempered:
1. Older Sidelites (Pre-2000 Homes)
Decorative sidelite panels beside front doors. Many were installed with leaded or textured annealed glass for aesthetics. If the glass is within 300mm of the door edge, it needs to be safety glass.
2. Interior French Doors
French doors between living rooms and dining rooms in homes built before 1990 often have annealed glass lites. These are high-risk — French doors swing into occupied rooms where people, especially children, can be in the path.
3. Basement Door Glass
Doors leading to basements, garages, or utility rooms sometimes have a single glass lite that was installed with whatever glass was on hand during construction. Not always tempered.
4. Patio Door Replacements
If a sliding patio door was replaced by a non-certified installer, the replacement glass may not meet safety standards. Always verify after any third-party glass work.
What If Your Glass Isn't Tempered?
Replace it. The OBC requirement isn't optional, and more importantly, the safety risk is real. A tempered glass replacement for a standard door lite costs:
| Door Lite Size | Approximate Cost (Installed) |
|---|---|
| Half lite (22" × 36") | $150-$250 |
| Three-quarter lite (22" × 48") | $200-$300 |
| Full lite (22" × 64") | $250-$400 |
| Sidelite panel (12" × 64") | $200-$350 |
We can replace the glass in most door lites without removing the door from its hinges. The front door glass replacement process takes 30-60 minutes per lite.
For decorative lites (textured, tinted, or patterned glass), we order tempered versions from the manufacturer. Lead time is typically 2-3 weeks for standard patterns.
A Note on Wired Glass
If your building has wired glass in doors or sidelites — the glass with a visible wire mesh embedded in it — be aware that wired glass does not meet modern safety glazing standards.
Wired glass was historically classified as safety glass because the wire holds broken pieces together. But impact tests show that wired glass breaks into large, sharp shards similar to annealed glass, and the wire edges add a tearing hazard.
Ontario schools, hospitals, and commercial buildings have been on a multi-year program to replace wired glass with tempered or ceramic fire-rated glass. If you own or manage a commercial property with wired glass in door locations, replacement should be on your maintenance plan.
Frequently Asked Questions
Where exactly is the tempered glass stamp located?
In one corner of the glass, usually the bottom corner closest to the hinge side. It's a small etched or sandblasted mark showing the manufacturer name, 'TEMPERED' or 'T', and a standards code.
What's the polarized light test for tempered glass?
Put on polarized sunglasses and look at the glass at an angle in bright daylight. Tempered glass shows faint rainbow-colored stress patterns caused by the tempering process. Annealed glass appears uniform.
Does the Ontario Building Code require tempered glass in shower doors too?
Yes. OBC Section 9.6.1 requires safety glazing in shower and bathtub enclosures, all door glass including sidelites within 300mm of a door, glass within 500mm of the floor, and glass adjacent to stairways and ramps.
Can I temper existing annealed glass that's already installed?
No. Tempering is a factory process — the glass is heated to 620°C and rapidly cooled. It cannot be done in the field. The glass must be removed and replaced with a factory-tempered unit.
Is wired glass considered safety glass?
Not anymore. Wired glass breaks into large, sharp pieces held loosely by the wire. Ontario buildings are actively replacing wired glass with tempered or ceramic alternatives that meet modern impact safety standards.
Not sure if your door glass is up to code? We do free visual inspections during any service call. Get in touch and we'll check every door and sidelight in your home while we're there.