A.Lynn Underwood, an engineer, licensed contractor, and building code official in Norfolk, Va., responds: The IRC contains a long list of hazardous locations where approved safety glazing — in the form of approved rigid plastic or laminated, tempered, heat-strengthened, or wired glass — has to be used. According to Section R308.4.7 of the 2006 IRC, the area above a window seat would be considered one of these hazardous locations for a window if all of the following conditions are true:

the exposed area of an individual pane is larger than 9 square feet;

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