When Is Tempered or Safety Glass Required Near Doors, Stairs, and Showers — IRC 2018 R308.4

Quick Answer

Under IRC 2018 Section R308.4, safety glazing (tempered or laminated glass) is required in several specific locations: glazing within 24 inches of a door edge in the same plane, glazing within 60 inches of the floor in a shower or bathtub enclosure, glazing in doors and sidelites within 24 inches of a door, glazing near stairways and landings, and glazing in windows with a sill height less than 18 inches above the floor when adjacent to a walking surface.

What R308.4 Actually Requires

IRC 2018 Section R308.4 lists specific hazardous glazing locations where safety glazing is required. Safety glazing includes tempered glass (marked CPSC 16 CFR 1201, Category II or equivalent) or laminated glass. The key hazardous locations are:

R308.4.1 — Glazing in door assemblies: All glass in swinging, sliding, and bifold doors shall be safety glazing, including glass panels adjacent to door openings where the glass is within 24 inches of the door's vertical edge and within 60 inches of the floor.

R308.4.2 — Glazing adjacent to doors: Glazing in panels within 24 inches of a door hinge or latch edge requires safety glazing when the glass is within 60 inches of the floor, unless separated from the door path by a wall, step, or cabinet.

R308.4.3 — Glazing in windows and walls: Glazing in individual fixed or operable panels with a bottom edge less than 18 inches above the adjacent walking surface AND within 36 inches horizontally of such surface requires safety glazing. This covers low sidelite windows, fixed panels in great rooms, and similar installations.

R308.4.5 — Glazing in tub/shower enclosures: All glazing in walls and enclosures forming the sides of a tub or shower shall be safety glazing, including wet walls and any glazing within 60 inches horizontally of the inside edge of the bathtub or shower threshold.

R308.4.7 — Glazing adjacent to stairways: Safety glazing is required in glazing that is within 36 inches horizontally of a stairway, landing, or ramp where the bottom edge of the glass is less than 60 inches above the stair nosing, walking surface, or ramp surface, and within 60 inches of the bottom landing.

Tempered glass is identified by a permanent etched or silkscreened mark in a corner of the glass, typically showing the CPSC 16 CFR 1201 designation, a category rating (Category I or II), and the manufacturer's identification. Category II tempered glass meets the higher impact resistance standard and is required in most residential hazardous locations. Laminated glass has a different marking but provides an alternative safety glazing option in all R308.4 locations.

Why This Rule Exists

Standard annealed glass breaks into large, sharp shards that can cause severe lacerating injuries when a person falls into it. The hazardous locations in R308.4 were identified through accident data as places where people are most likely to fall against or into glass — shower slips, door-swing impacts, stair falls, and falls near floor-level windows. Tempered glass breaks into small, relatively harmless granules. Laminated glass holds together when broken, preventing large shard projection. Both substantially reduce injury severity when glass fails.

What the Inspector Checks at Rough and Final

At rough the inspector reviews the window schedule for glazing specifications in hazardous locations. At final inspection the inspector looks for the safety glazing marking on every pane in a hazardous location. Tempered glass is permanently marked in a corner with the CPSC 16 CFR 1201 designation, the manufacturer's mark, and the category rating. The inspector will check: (1) all glass in shower and tub enclosures; (2) all sidelite panels within 24 inches of a door edge; (3) windows with sills below 18 inches; (4) glazing near stairways. If the marking is absent or cannot be found (obscured by a frame), the inspector may require a tempering certificate from the window manufacturer.

What Contractors Need to Know

Order windows in hazardous locations as tempered from the manufacturer — standard annealed windows cannot be tempered in the field. When placing a window order, identify every location that may require safety glazing and mark those units on the order. The 18-inch sill height rule catches many windows that designers place low for visual effect — verify sill heights on the plans for all rooms. In shower and tub enclosures, specify tempered glass for all enclosure panels and any window within 60 inches of the tub rim or shower threshold.

The 60-inch wet-area rule for tubs and showers is wider than many contractors expect. A window installed in the wall above a bathtub — even if it is above the tile line and not part of the enclosure — is still within the 60-inch horizontal zone if the tub edge is close to that wall. Measure the 60-inch radius from the inside edge of the tub or shower threshold in all directions and treat every glazed panel within that distance as requiring safety glass. A window that appears to be outside the enclosure but sits at a sill height of 14 inches above the bathroom floor within 60 inches of the tub edge fails R308.4.5. Verify the 60-inch horizontal distance at the window schedule review, not at the frame inspection.

What Homeowners Get Wrong

Homeowners frequently replace a cracked or fogged window with standard replacement glass without recognizing that the original installation was in a hazardous location requiring safety glazing. A low sidelite next to the front door, a window in the shower enclosure, or a low bedroom window above a walkway are all locations where the replacement glass must be tempered. A hardware store glass cutter will install standard glass unless specifically asked for tempered, so homeowners must know to specify it.

Another common mistake is installing a decorative sidelite next to a new front door without checking whether the glass panel falls within 24 inches of the door edge. Standard decorative glass panels available at home improvement stores are frequently not safety-rated and may not comply with R308.4.2 for door-adjacent sidelites.

Homeowners also sometimes remove safety glazing markings when cutting glass to size for a custom application. Tempered glass cannot be cut after tempering — it will shatter. Glass that needs to be cut must be annealed glass, but if the final installation location is a hazardous location, it must be ordered pre-cut in the correct size as tempered. There is no acceptable field modification to convert standard glass to safety glazing.

A related error occurs when homeowners shop for replacement glass at a local hardware store and accept whatever the store supplies without specifying the hazardous location requirement. Glass shops will install standard annealed glass unless the customer explicitly requests safety glazing. The resulting installation is non-compliant and creates liability if an injury occurs. Before placing any glazing replacement order, identify whether the installation falls within one of the R308.4 hazardous zones, and confirm in writing that the supplied glass carries the appropriate CPSC 16 CFR 1201 marking. If the inspector later asks for a tempering certificate and none was provided with the order, the homeowner may have no documentation to support the installation.

State and Local Amendments

IRC 2018 R308.4 is adopted in Texas, Georgia, Virginia, North Carolina, South Carolina, Tennessee, Alabama, Mississippi, Kentucky, and Missouri. Safety glazing requirements are core life-safety provisions and are rarely amended at the local level. Some jurisdictions apply safety glazing requirements to skylight installations that are not explicitly covered by R308.4, as a local amendment.

IRC 2021 expanded R308.4 to clarify the stairway glazing requirements and to add provisions related to glass railings (guards) that use structural glass. The core hazardous locations — doors, sidelites, showers, low windows, and stairways — are the same in IRC 2018 and IRC 2021. States on IRC 2018 apply the same fundamental glazing hazard locations.

When to Hire a Licensed Contractor

Glazing installation near showers, doors, and stairs is specialty work. A licensed glazier or a window contractor familiar with safety glazing requirements is the appropriate professional for shower enclosure glass, entry sidelites, and custom window installations in hazardous locations. For standard replacement windows, verify the replacement unit is appropriate for the location before ordering. Glass cutting and custom framing for shower enclosures requires professional tools and knowledge of tempering requirements — this is not a DIY project in most cases.

Common Violations Found at Inspection

• Standard annealed glass installed in shower or tub enclosure — all enclosure glazing must be safety glass per R308.4.5
• Sidelite panel within 24 inches of a door edge without safety glazing marking
• Low bedroom or living room window with sill below 18 inches and within 36 inches of the walking surface installed with standard glass
• Replacement glass installed in a hazardous location using standard annealed glass because the installer was not told it required tempering
• Safety glazing marking not visible in the installed frame corner — inspector cannot verify compliance without a certificate
• Window within 60 inches horizontally of a bathtub rim installed with standard glass — the 60-inch wet area rule extends beyond the enclosure itself
• Glass stair railing panel without listing as a structural safety glazing assembly