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;
the bottom edge of the glass is less than 18
inches above the floor;
the top edge of the glass is more than 36 inches
above the floor;
there is at least one walking surface within 36
inches — horizontally — of the
glass.
Because a window seat is typically used not as a
walking surface but for sitting on, a window
adjacent to a window seat probably
wouldn’t meet these criteria. But the
intent of the building code is to minimize the
potential for falling into the glass under a
variety of situational conditions (such as when
surfaces are wet or slippery, for example). So in
some jurisdictions, where the model building code
has been amended to reflect local conditions and
custom, it’s possible that some inspectors
would require safety glass above certain window
seats.
When in doubt, always check with your local
building official for the final word.