Safety glazing, usually tempered or laminated glass, is required wherever 2021 IRC Section R308.4 defines a hazardous location: in doors, beside doors, in large low windows, in guards, around tubs and showers, and beside stairs and ramps. Each location has its own trigger heights and distances, listed in the table below.
Safety glazing is glass that has passed an impact test so that a person falling into it is less likely to be badly cut. The 2021 International Residential Code (IRC) names the locations in Section R308.4 and the test in Section R308.3.1. The adopted code edition and your local amendments govern, so confirm them with the building department before you order windows.
Key facts
- Glazing in swinging, sliding and bifold doors is a hazardous location, with an exception for openings a 3-inch-diameter sphere cannot pass (2021 IRC Section R308.4.1).
- Glazing beside a door is hazardous when its bottom exposed edge is less than 60 inches above the floor and it is within 24 inches of either side of the door (2021 IRC Section R308.4.2).
- A window pane is hazardous only when it is larger than 9 square feet, its bottom edge is under 18 inches, its top edge is over 36 inches, and a walking surface is within 36 inches (2021 IRC Section R308.4.3).
- Glazing next to tubs, showers, spas and pools is hazardous when its bottom edge is less than 60 inches above the standing or walking surface (2021 IRC Section R308.4.5).
- Glazing beside stairs and ramps is hazardous when its bottom edge is less than 36 inches above the walking surface (2021 IRC Section R308.4.6).
- Each pane in a hazardous location needs a visible manufacturer's designation, or a label (2021 IRC Section R308.1).
Where is tempered glass required in a house?
Tempered glass is required in the seven hazardous locations of 2021 IRC Section R308.4, plus in any glazing the code sends to the impact test. The table summarizes each one.
2021 IRC Section R308.4: the seven hazardous locations and their trigger dimensions.
| Location | Section | Trigger | Main exceptions |
|---|---|---|---|
| Glazing in doors | R308.4.1 | Any glazing in fixed or operable panels of swinging, sliding and bifold doors | Openings a 3-inch sphere cannot pass; decorative glazing |
| Glazing adjacent to doors | R308.4.2 | Bottom exposed edge less than 60 inches above floor, and within 24 inches of either side of the door (or within 24 inches of the hinge side of an in-swinging door on a wall less than 180 degrees from the door plane) | Decorative glazing; intervening wall or barrier; closet or storage 3 feet or less deep; fixed panel of patio doors |
| Glazing in windows | R308.4.3 | All of: pane over 9 square feet, bottom edge under 18 inches, top edge over 36 inches, walking surface within 36 inches | Decorative glazing; horizontal rail 34 to 38 inches high; outboard panes 25 feet or more above grade |
| Guards and railings | R308.4.4 | All glazing in guards and railings, regardless of area or height | Structural baluster rule in R308.4.4.1 |
| Wet surfaces | R308.4.5 | Bottom exposed edge less than 60 inches vertically above the standing or walking surface | More than 60 inches horizontally from the water's edge or shower edge |
| Adjacent to stairs and ramps | R308.4.6 | Bottom exposed edge less than 36 inches above the walking surface of stairs, landings and ramps | Horizontal rail 34 to 38 inches high; glazing 36 inches or more horizontally away |
| Adjacent to the bottom stair landing | R308.4.7 | Glazing less than 36 inches above the landing and within a 60-inch horizontal arc less than 180 degrees from the bottom tread nosing | Guard complying with R312 and glass more than 18 inches from the guard |
Read the trigger column as a test. A window can sit inside one of these zones and still be exempt, and a small window can fail a different test. Work through each location for each pane.
Does glass near a door need to be tempered?
Yes, when it is within 24 inches of the door and its bottom exposed edge is less than 60 inches above the floor or walking surface.
That catches the sidelight beside an entry door and the narrow window next to a patio door. A closet or storage area 3 feet or less deep is exempt from this section, but its glazing must still pass the window test in R308.4.3. Glass in the door itself falls under R308.4.1, fixed and operable panels alike.
When does a window need tempered glass?
A window pane needs tempered glass only when all four conditions in Section R308.4.3 are true at once: size, bottom edge, top edge and nearby walking surface, as in the table.
Failing any one takes the pane out of this section. A large window with a 24 inch sill is not caught here, though another location may catch it. The rail exception needs a rail that withstands a horizontal load of 50 pounds per linear foot without contacting the glass and has a cross-sectional height of at least 1-1/2 inches. Floor-to-ceiling windows beside a deck or patio are the usual candidates, so put the pane size on the window schedule rather than relying on sill height alone.
Does a bathroom window need tempered glass?
Only when the glazing is close to the water and low. Section R308.4.5 applies to glazing in or beside hot tubs, spas, whirlpools, saunas, steam rooms, bathtubs, showers and pools, to single glazing and to each pane in multiple glazing.
A window above a tub with its sill under 60 inches needs safety glazing. A window beyond 60 inches horizontally from the water's edge or shower edge does not. Shower doors and enclosures fall under glazing in doors and enclosures, and Table R308.3.1(1) gives them Category II for both size ranges.
Do windows next to stairs need safety glass?
Yes, when the bottom edge is less than 36 inches above the walking surface of a stair, a landing between flights, or a ramp.
The horizontal rail exception uses the same 50 pounds per linear foot and 1-1/2 inch requirements as the window rule. Section R308.4.7 separately covers the bottom landing, where the exception depends on a guard complying with Section R312. Stair geometry is covered in stair riser height code, rail and guard heights in handrail height code, and the floor opening in framing a stair opening.
Tempered vs laminated glass: which is allowed?
The code sets an impact test and a label, not a single glass type. Tempered glass is heat-treated so it is stronger than ordinary glass and breaks into small pieces. Laminated glass bonds layers with an interlayer so that broken pieces tend to stay in place.
Section R308.3.1 requires testing to the federal standard CPSC 16 CFR 1201 at Category II unless Table R308.3.1(1) says otherwise. Glazing not in doors or in tub, shower, hot tub, sauna or steam room enclosures may instead be tested to ANSI Z97.1 at Class A unless Table R308.3.1(2) says otherwise. Both tables split at 9 square feet.
Section R308.1 requires each pane in a hazardous location to carry a permanent designation naming who applied it, the glass type and the safety standard, or a label. Order the glass as "safety glazing" on the schedule and ask for the designation.
What about skylights and sloped glazing?
Skylights fall under Section R308.6, which lists allowed materials: laminated glass with a polyvinyl butyral interlayer, fully tempered glass, heat-strengthened glass, wired glass and approved rigid plastics. The interlayer must be not less than 0.015 inch for panes 16 square feet or less with the highest point not more than 12 feet above a walking surface, and not less than 0.030 inch otherwise (R308.6.2).
Broken glass retention screens apply in some combinations (R308.6.3 to R308.6.5). Unit skylights in a roof with a pitch of less than three units vertical in 12 units horizontal need a curb at least 4 inches above the roof plane unless the manufacturer says otherwise (R308.6.8). For the wall openings that hold doors and windows, see the header size chart.
How do you show safety glazing on a framing plan?
Mark every window and door in a hazardous location with a note, for example T or SAFETY GLAZING, and define it in the legend.
Safety glazing does not change the rough opening, but it changes the order and the schedule. Flag a door sidelight, a tall window beside a patio or a window above a tub before the window package is ordered, because the glass cannot be swapped on site. Check each opening for distance to the nearest door, tub, shower, stair or walking surface. Low bedroom egress windows need the check too; the sizing rules are in egress window requirements. Symbols and legends are in framing plan symbols.
Framing Plan is a preliminary drawing aid. It draws joist layouts, beams and openings and exports PNG, PDF and DXF. It does not check glazing or code compliance, and its editor works in millimeters with a bundled sample profile of demo figures, so type your glazing notes from the code and the window manufacturer's data. The full text of Section R308 is in the 2021 IRC on ICC's site.
Summary
The 2021 IRC requires safety glazing in seven hazardous locations: doors, beside doors, large low windows, guards and railings, around wet surfaces, beside stairs and ramps, and at the bottom stair landing. Each has its own trigger heights and distances, and several have exceptions for rails, barriers and distance. Every hazardous-location pane needs a visible designation or label.
Mark the affected windows and doors on a preliminary drawing in the Framing Plan studio, then confirm the glazing with the adopted code and the window supplier.