Safety Glazing (Tempered Windows) | CRC § R308.4

Introduction

California's Residential Code (CRC) regarding safety glazing or tempered windows are described below. These sections of the code are designed to enhance safety in residential buildings by outlining specific areas where safety measures such as tempered glass should be used to minimize the risk of injuries from broken glass.

Before we explore the specifics of these code sections, let's familiarize ourselves with a few of the technical terms involved:

  1. Glazing: This term refers to the installation of glass in a building, such as in windows, doors, or other panels. The CRC defines Glazing Area as "The interior surface area of all glazed fenestration, including the area of sash, curbing or other framing elements, that enclose conditioned space. Includes the area of glazed fenestration assemblies in walls bounding conditioned basements."
  2. Tempered Windows or Safety Glazing: This is a type of safety glass that undergoes a process of heating and rapid cooling, making it much stronger than regular glass. If broken, it shatters into small granular pieces instead of jagged shards, reducing the risk of injury.
  3. Operable Panels: These are sections of a window, door, or other construction element that can be opened or moved.
  4. Bifold doors: These are a type of door made from several panels that fold back onto each other in a concertina effect.
  5. In-fill Panels: These are panels used to fill a gap in a construction, often seen in railings or guards.
  6. Nosing: The edge of a stair tread that extends beyond the riser; in other words, the edge of the stair step that sticks out over the step below it. It the CRC it is defined as "The leading edge of treads of stairs and of landings at the top of stairway flights."
  7. Rad (Radian): This is a unit of measurement for angles. A complete circle measures 2π radians, which is approximately 6.28 rad, and half a circle is approximately 3.14 rad.

These California Residential Code sections provide safety rules for using glazing in various areas of a residential building. The code specifies locations that are considered hazardous and require safety glazing, including certain areas around doors and windows, hot tubs and showers, stairs and ramps, and more.

Scope

The locations specified in Sections R308.4.1 through R308.4.7 of the CRC shall be considered to be hazardous locations. Safety glazing, or tempered windows, shall be provided in these locations. See the Safety Glazing Handout for more information.

Glazing in Doors

Glazing in fixed and operable panels of swinging, sliding and bifold doors shall be considered to be a hazardous location except decorative glazing and glazed openings of a size through which a 3-inch-diameter (76 mm) sphere is unable to pass.

Glazing Adjacent to Doors

Glazing in an individual fixed or operable panel adjacent to a door shall be considered to be a hazardous location where the bottom exposed edge of the glazing is less than 60 inches (1524 mm) above the floor or walking surface and it meets either of the following conditions: Where the glazing is within 24 inches (610 mm) of either side of the door in the plane of the door in a closed position OR where the glazing is on a wall less than 180 degrees (3.14 rad) from the plane of the door in a closed position and within 24 inches (610 mm) of the hinge side of an in-swinging door.

Exceptions:

  1. Decorative glazing.
  2. Glazing where there is an intervening wall or other permanent barrier between the door and the glazing.
  3. Glazing where access through the door is to a closet or storage area 3 feet (914 mm) or less in depth.
  4. Glazing that is adjacent to the fixed panel of patio doors.

Glazing in Windows

Glazing in an individual fixed or operable panel that meets all of the following conditions shall be considered to be a hazardous location and will need to be tempered: The exposed area of an individual pane is larger than 9 square feet (0.836 m2), the bottom edge of the glazing is less than 18 inches (457 mm) above the floor, the top edge of the glazing is more than 36 inches (914 mm) above the floor, and one or more walking surfaces are within 36 inches (914 mm), measured horizontally and in a straight line, of the glazing.

Exceptions:

  1. Decorative glazing.
  2. Where glazing is adjacent to a walking surface and a horizontal rail is installed 34 to 38 inches (864 to 965 mm) above the walking surface. The rail shall be capable of withstanding a horizontal load of 50 pounds per linear foot (730 N/m) without contacting the glass and have a cross-sectional height of not less than 11/2 inches (38 mm).
  3. Outboard panes in insulating glass units and other multiple glazed panels where the bottom edge of the glass is 25 feet (7620 mm) or more above grade, a roof, walking surfaces or other horizontal [within 45 degrees (0.79 rad) of horizontal] surface adjacent to the glass exterior.

Glazing in Guards and Railings

Glazing in guards and railings, including structural baluster panels and nonstructural in-fill panels, regardless of area or height above a walking surface shall be considered to be a hazardous location.

Glazing and Wet Surfaces

Glazing in walls, enclosures or fences containing or adjacent to hot tubs, spas, whirlpools, saunas, steam rooms, bathtubs, showers and indoor or outdoor swimming pools where the bottom exposed edge of the glazing is less than 60 inches (1524 mm) measured vertically above any standing or walking surface shall be considered to be a hazardous location. This shall apply to single glazing and each pane in multiple glazing.

Exception:

  1. Glazing that is more than 60 inches (1524 mm), measured horizontally, from the water's edge of a bathtub, hot tub, spa, whirlpool or swimming pool or from the edge of a shower, sauna or steam room.

Glazing Adjacent to Stairs and Ramps

Glazing where the bottom exposed edge of the glazing is less than 36 inches (914 mm) above the plane of the adjacent walking surface of stairways, landings between flights of stairs and ramps shall be considered to be a hazardous location.

Exceptions:

  1. Where glazing is adjacent to a walking surface and a horizontal rail is installed at 34 to 38 inches (864 to 965 mm) above the walking surface. The rail shall be capable of withstanding a horizontal load of 50 pounds per linear foot (730 N/m) without contacting the glass and have a cross-sectional height of not less than 11/2 inches (38 mm).
  2. Glazing 36 inches (914 mm) or more measured horizontally from the walking surface.

Glazing Adjacent to the Bottom Stair Landing

Glazing adjacent to the landing at the bottom of a stairway where the glazing is less than 36 inches (914 mm) above the landing and within a 60-inch (1524 mm) horizontal arc less than 180 degrees (3.14 rad) from the bottom tread nosing shall be considered to be a hazardous location. 

Exception:

  1. Where the glazing is protected by a guard complying with Section R312 and the plane of the glass is more than 18 inches (457 mm) from the guard.