One area where Code Officials, Architects and other Construction Professionals often incorrectly interpret the code is as it applies to Safety Glazing (Tempered Windows). Many times the language of the code related to safety glazing is easily understood, however the “Exceptions” included with the code are often overlooked.
For example, reviewing the plan to the right, we could simply read the code and decide the window next to the Bedroom 2 Closet Door needs safety glazing. IRC Code R.308.4.2 states, “Glazing in an individual fixed or operable panel adjacent to a door where the nearest vertical edge of the glazing is within a 24-inch (610 mm) arc of either vertical edge of the door in a closed position and where the bottom exposed edge of the glazing is less than 60 inches (1524 mm) above the floor or walking surface shall be considered a hazardous location.” If we were to stop reading there and measure the 24-inch arc, measure 60 inches from the floor and see the window falls within the arc and below 60 inches, we might assume the window is in a hazardous location and needs safety glazing. However, this situation provides a good example of how simply reading the code without taking into consideration the Exceptions leaves the reader misinformed.
If we take a further look at the Exceptions to R308.4.2, we find that if certain conditions are present, this is no longer considered a hazardous location. The key Exception to consider is #4 which reads, “Where access through the door is to a closet or storage area 3 feet (914 mm) or less in depth, glazing in this application shall comply with section R308.4.3.” This Exception tells us that if the door is accessing a closet which is 3 feet or less in depth, it is exempt from R308.4.2. In this case, the closet is 3 feet deep. The Exception also directs us to R308.4.3 which applies to windows that are close to the floor or over a certain size (R308.4.3 code language is included below). After review of R308.4.3, we find that since the window in this case does not meet the criteria of R308.4.3, it would not be deemed in a hazardous location and, therefore, would not be required to have safety glazing.
The safety glazing case outlined above is just one example of how construction professionals have an obligation to interpret the code in its entirety, including the associated Exceptions. Using or not using safety glazing at the appropriate times will impact both our schedules and budgets and simply following the code as it’s written can help prevent incorrect applications.
For more information, contact Burgess Construction Consultants, Inc. at 888-644-6489.
2012 International Residential Code:
R308.4.2 Glazing adjacent to doors. Glazing in an individual fixed or operable panel adjacent to a door where the nearest vertical edge of the glazing is within a 24-inch (610 mm) arc of either vertical edge of the door in a closed position and where the bottom exposed edge of the glazing is less than 60 inches (1524 mm) above the floor or walking surface shall be considered a hazardous location.
Exceptions:
1. Decorative glazing.
2. When there is an intervening wall or other permanent barrier between the door and the glazing.
3. Glazing in walls on the latch side of and perpendicular to the plane of the door in a closed position.
4. Where access through the door is to a closet or storage area 3 feet (914 mm) or less in depth. Glazing in this application shall comply with section R308.4.3.
5. Glazing that is adjacent to the fixed panel of patio doors.
R308.4.3 Glazing in windows. Glazing in an individual fixed or operable panel that meets all of the following conditions shall be considered a hazardous location:
1. The exposed area of an individual pane is larger than 9 square feet (0.836 m2);
2. The bottom edge of the glazing is less than 18 inches (457 mm) above the floor;
3. The top edge of the glazing is more than 36 inches (914 mm) above the floor; and
4. 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. When a horizontal rail is installed on the accessible side(s) of the glazing 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 be a minimum of 11/2 inches (38 mm) in cross sectional height.
3. Outboard panes in insulating glass units and other multiple glazed panels when 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.
Technical Author: Craig Brooks, Dallas Division President