Where Is Tempered Glass Required in Arizona Homes?
If you have received a replacement-window proposal, you may have noticed that some windows include an additional charge for tempered glass.
That can raise a fair question:
Why does one window require tempered glass while an almost identical window in another room does not?
Tempered glass is generally required in locations where broken glass could create a greater risk of injury. Building codes refer to these areas as hazardous locations.
The requirement depends on the glass location, size, height, proximity to walking surfaces, and relationship to doors, tubs, showers, stairs, and other features.
Here are the most common places where safety glazing may be required in an Arizona home.
What Is Tempered Glass?
Tempered glass is heat-treated to make it stronger than ordinary annealed glass.
When annealed glass breaks, it can form large, sharp shards. Tempered glass is designed to break into many smaller pieces, reducing the likelihood of severe cutting injuries.
You have probably seen tempered glass in:
Patio doors
Vehicle side windows
Shower enclosures
Storefront doors
Glass tabletops
Tempered glass is one form of safety glazing. Laminated glass and certain other approved materials can also qualify, depending on the application and code requirements.
Glass in Doors
Glazing installed in swinging, sliding, and bifold doors is generally treated as a hazardous location and requires safety glazing.
This commonly includes:
Sliding patio doors
French doors
Hinged exterior doors containing glass
Bifold glass doors
Multi-slide door panels
This is why the glass in a patio door is normally tempered even when nearby window glass may not be.
There are limited exceptions for certain small or decorative openings, but ordinary glass doors should generally be expected to contain safety glazing. Always check your local codes!
Windows Next to Doors
A window does not automatically require tempered glass merely because it is in the same room as a door.
Under the model residential code, safety glazing is generally required when the glass is sufficiently close to the door and low enough above the walking surface.
A commonly applied test considers whether:
The glazing is within 24 inches horizontally of the door’s vertical edge, and
The bottom exposed edge of the glass is less than 60 inches above the walking surface
Certain exceptions may apply when the glass is protected by an intervening wall or permanent barrier, positioned in a different plane, or located next to specific types of doors.
The exact layout matters. Moving a window a few inches or changing the height of its glass can change the requirement. Always check your local codes!
Glass in Patio Doors
The operable and fixed panels in a sliding glass door assembly are generally safety glazed.
Homeowners sometimes assume that only the sliding panel needs tempering because it is the part that moves. In reality, the stationary panel remains part of the door assembly and can still be exposed to human impact.
When replacing a complete patio door, expect the primary glass panels to use safety glazing. Always check your local codes!
Windows Near Bathtubs and Showers
Glass near wet surfaces presents a greater injury risk because people may slip or fall.
Safety glazing is generally required when glass is located close to:
Bathtubs
Hot tubs
Spas
Whirlpools
Showers
Saunas
Steam rooms
Indoor or outdoor swimming pools
The model residential code generally considers both horizontal proximity to the water’s edge and vertical proximity to a standing or walking surface.
A frequently applied threshold is 60 inches horizontally from the water’s edge and less than 60 inches vertically above the relevant surface.
This commonly affects bathroom windows positioned above or beside a bathtub.
The rule is based on the actual glass location, not merely the fact that the window is located in a bathroom. A high bathroom window located well away from a shower may not require tempering, while a low window immediately beside a tub often will. Always check your local codes!
Large, Low Windows Near Walking Surfaces
Some large windows require safety glazing even when they are not beside a door or bathtub.
Under the model residential code, an individual pane is generally considered hazardous when all of the following conditions are present:
The exposed glass area exceeds 9 square feet
The bottom edge is less than 18 inches above the floor
The top edge is more than 36 inches above the floor
A walking surface is located within 36 inches horizontally of the glass
All four conditions generally must be satisfied for this particular provision to apply.
This rule frequently affects large picture windows installed close to the floor.
A large window is not automatically tempered. A low window is not automatically tempered. The complete combination of glass area, height, and walking-surface proximity determines the requirement. Always check your local codes!
Glass Near Stairs, Ramps and Landings
Windows near stairs can create an increased risk because a person may fall toward the glass.
Safety glazing may be required when glazing is located beside:
Stairways
Stair landings
Ramps
Intermediate landings
Bottom stair landings
The model code uses measurements based on the window’s horizontal proximity to the walking surface and the height of the exposed glass.
Separate provisions address glass near the bottom landing of a staircase.
Stairway conditions can be difficult to evaluate from a photograph because measurements may be taken from treads, landings, walking surfaces, and the bottom exposed edge of the glass.
These locations should be field-measured rather than guessed. Always check your local codes!
Does Every Pane in an XO or XOX Window Need to Be Tempered?
Not necessarily.
In a multi-panel window, each individual pane or panel may be evaluated based on its specific location.
For example, one side of an XOX sliding window might be close enough to a door, bathtub, or walking surface to require safety glazing while another panel does not.
However, requirements can also depend on how the window is tested, manufactured, labeled, and approved. A manufacturer or building department may require a broader configuration than the minimum condition a homeowner expects from looking at the opening.
This is why tempered-glass charges should be determined during the measuring and ordering process.
How Can You Tell Whether Existing Glass Is Tempered?
Tempered glass generally carries a permanent safety-glazing mark, commonly called a bug, near one corner of the pane.
The marking may identify:
The manufacturer
The applicable safety standard
The type of safety glazing
The certification organization
Because the mark can be small, etched, or partially obscured, it is sometimes difficult to see.
Lack of an easily visible mark does not prove that glass is unsafe, but approved tempered glass installed under modern requirements is generally expected to carry permanent identification.
Tempered Glass vs. Laminated Glass
Tempered and laminated glass improve safety differently.
Tempered Glass
Tempered glass is strengthened through heat treatment and breaks into relatively small pieces.
Laminated Glass
Laminated glass contains an interlayer that helps hold broken glass together.
Laminated glass can be useful where security, sound reduction, storm resistance, or post-breakage retention is important. However, the glass must be properly manufactured and labeled to qualify as approved safety glazing.
Not every piece of thick glass or dual-pane glass is safety glass.
Why Tempered Glass Costs More
Tempering adds manufacturing steps to the glass-production process.
The glass must be:
Cut to its final dimensions
Fabricated with necessary holes or edge work
Heat-treated
Certified and permanently marked
Incorporated into the insulated glass unit
After glass has been tempered, it generally cannot be cut or resized.
The additional manufacturing, handling, certification, and breakage risk contribute to the higher price.
Can Existing Non-Tempered Glass Be Left in Place?
Existing conditions do not automatically establish what is permitted during replacement.
A house may have been built under an older code. The original glass may have been installed incorrectly, or the surrounding conditions may have changed during a remodel.
When windows or doors are replaced, the new product may need to comply with the currently adopted requirements applicable to that project.
Never assume that the replacement can use ordinary glass simply because the existing window does.
Arizona Requirements Can Vary by Jurisdiction
Arizona does not operate under one single locally amended residential code enforced identically in every city.
Phoenix, Mesa, Chandler, Gilbert, Scottsdale, Prescott, Flagstaff, Maricopa County, and other jurisdictions may adopt different code editions or local amendments.
Project type also matters. Single-family homes, multifamily buildings, commercial properties, and manufactured homes may be governed by different requirements.
The final determination should come from:
The code adopted by the local jurisdiction
Applicable local amendments
The authority having jurisdiction
Approved plans
The project’s licensed contractor or design professional
This article provides general educational information and should not replace a project-specific code review. Always check your local codes!
Final Thoughts
Tempered glass is not an arbitrary upgrade added to make a window more expensive.
It is a safety requirement intended to reduce injuries in locations where people are more likely to fall into or pass through glass.
The most common locations include:
Glass doors
Windows beside doors
Windows near tubs and showers
Large windows close to the floor
Windows near stairs, ramps, and landings
At Modern Resolution Windows & Doors, we evaluate each opening during the measuring and ordering process to help ensure the correct glass is specified for the project.
We install replacement windows and doors throughout Phoenix, Scottsdale, Mesa, Tempe, Chandler, Gilbert, Glendale, Peoria, Prescott, Flagstaff, and surrounding Arizona communities.
Call 480-665-5732 or schedule a free consultation to discuss your window or door replacement project!