Tempered and safety glazing to code in Phoenix

Building code requires safety glazing in specific openings it calls hazardous locations, and an inspector checks for a permanent mark on the glass to prove it. We supply and install to those requirements, and we’ll tell you at the measure which of your openings are affected.

Your building official has the final word on any of this. What’s below is what they’re looking at.

The hazardous locations

These are the categories that catch commercial work. If an opening falls into one, the glass in it has to be safety glazing.

• Glass in doors. All fixed and operable panels, swinging, sliding, bifold and revolving. No size exemption.
• Glass adjacent to doors, within a 24 inch arc of the door in its closed position, where the bottom edge sits less than 60 inches above the floor.
• Large glass near a walking surface. All four conditions have to be true at once: the pane is over 9 square feet, the bottom edge is under 18 inches, the top edge is over 36 inches, and there’s a walking surface within 36 inches horizontally.
• Glass in guards and railings, including both structural balusters and non-structural infill panels, regardless of area or height.
• Glass near wet surfaces, meaning tubs, showers, saunas and pools, where the bottom edge is under 60 inches above the standing surface.
• Glass alongside stairways and ramps, bottom edge under 60 inches above the walking surface.
• Glass at the bottom stairway landing, within 60 inches horizontally in an arc from the bottom tread nosing, bottom edge under 60 inches.

The one that catches most commercial buildings is the third. A full-height window in a lobby or a corridor meets all four conditions without anyone thinking of it as a hazard.

Which code edition applies to your building

Arizona has no mandatory statewide building code, so every jurisdiction adopts its own. That produces a split right now that matters if you manage more than one property.

The City of Phoenix adopted the 2024 building code, effective 1 August 2025. Unincorporated Maricopa County is still on the 2018 code, adopted in August 2022. Two properties a short drive apart can be inspected against different editions, and the 2024 code tightened glazing requirements rather than loosening them.

We confirm which edition governs your address before ordering, and we’d suggest confirming it with your plans examiner on anything permitted.

Category I and Category II

Safety glazing is proven by impact test, and there are two energy levels. Both use a 100 pound impactor. The difference is how far it falls.

• Category I: an 18 inch drop, about 150 foot-pounds. Permitted for doors and adjacent panels where no single glazed piece exceeds 9 square feet.
• Category II: a 48 inch drop, about 400 foot-pounds. Required for sliding doors, shower and tub enclosures, and any door glazing over 9 square feet.

Over 9 square feet, everything is Category II. Below it, some assemblies can be Category I, but sliding doors can’t. Category II satisfies Category I, so when in doubt the higher category is never wrong.

You’ll also see glass marked to ANSI Z97.1, in Class A and Class B. They’re the same two energy levels: Class A matches Category II, Class B matches Category I. The difference is legal rather than physical. The federal regulation is mandatory and administered by the Consumer Product Safety Commission; the ANSI standard is a voluntary consensus standard that code invokes for certain applications, mostly interior ones, handrails and similar. Most fabricators label to both.

Tempered, heat-strengthened and laminated

These get used interchangeably in conversation and they are not interchangeable in a building.

Fully tempered

Heated then rapidly quenched, which puts the surfaces into deep compression. Roughly four times the strength of annealed glass, with surface compression at or above 10,000 psi. When it breaks it dices into small blunt pieces and the entire lite empties out of the opening at once. That fragmentation is exactly why code accepts it as safety glazing, and it’s also why a broken tempered storefront leaves nothing behind.

One thing worth knowing: fully tempered glass carries a small risk of spontaneous breakage from nickel sulfide inclusions, years after installation, with nothing having hit it. It’s rare, it’s real, and it’s inherent to the process.

Heat-strengthened

Same furnace, slower cooling. About twice the strength of annealed, with surface compression in the 3,500 to 7,500 psi range. It breaks into larger fragments that tend to stay in the opening rather than falling out.

Heat-strengthened glass is not safety glazing on its own. It qualifies only when laminated. What it’s for is wind load and thermal stress resistance in openings where safety glazing isn’t required, and it does not carry the spontaneous breakage risk that fully tempered does.

Laminated

Two or more lites bonded to an interlayer. It cracks, and the interlayer holds the pieces. That retention is why code requires laminated glass in guards and railings, and it’s the right answer for any opening where glass falling out is the actual hazard, or where you want the opening to stay closed after a break.

Permanent labeling, and why it isn’t optional

Every lite in a hazardous location has to carry the manufacturer’s designation identifying the fabricator, the glass type and the standard it meets. Code is specific about the form: acid etched, sandblasted, ceramic fired, laser etched, embossed, or otherwise applied so it can’t be removed without being destroyed.

A printed sticker is not a label. An unmarked lite in a hazardous location fails inspection, and the fix is a new lite, not a certificate after the fact.

If you’re buying glass on price and it arrives without a permanent mark, you’re buying it twice.

Tempered glass cannot be cut after tempering

This is the single fact that explains commercial glass lead times, so it’s worth stating plainly. Tempering leaves the surfaces in compression and the core in tension. Cut, drill or notch into it and the crack reaches the tensile core and the whole lite disintegrates on the bench.

All cutting, edge finishing, hole drilling, notching and cutouts happen while the glass is annealed, before it goes through the furnace. There is no adjusting a lite on site. A measurement that’s off by a quarter inch is a re-order.

Which is why a technician measures rather than a customer, and why we don’t quote commercial glass off a phone description. See commercial glass for how the quote and deposit work.

Our warranty

Glass and installation carry a lifetime limited warranty on our workmanship, for as long as you own the property.

Common questions

Does my commercial glass have to be tempered?

If it’s in a door, within 24 inches of a door below 60 inches, a large pane near a walking surface, or in a guard or railing, it has to be safety glazing. Tempered is the usual answer, and laminated is the other one.

What’s the difference between tempered and safety glass?

Safety glass is the category. Tempered and laminated are two ways of meeting it. Heat-strengthened glass is not safety glass unless it’s laminated.

Can you cut down a piece of tempered glass to fit?

No. It shatters. Every cut and hole is made before the glass is tempered, which is why commercial glass is fabricated to a measurement rather than trimmed on site.

My glass has no stamp on it. Is that a problem?

In a hazardous location, yes. Code requires a permanent mark that can’t come off without being destroyed, and an inspector will look for it. A sticker doesn’t count.

Which code does Phoenix use?

The City of Phoenix has been on the 2024 building code since 1 August 2025. Unincorporated Maricopa County is still on the 2018 code. Check which jurisdiction your address sits in, because it changes what applies.

Why did my window break when nothing hit it?

Either thermal stress, where the middle of the pane heats faster than the shaded edges until the edge fails in tension, or a nickel sulfide inclusion in tempered glass. Both happen here. If it’s the same opening twice, it’s usually the first one and the glass specification needs to change.

Get it specified properly

Call (602) 777-3717 Monday to Friday, 7:30am to 5:00pm. A technician measures, identifies which openings are hazardous locations, and the written quote names the glass type going into each one.