Glazing that meets the ASTM E-119 standard are classified as “fire resistive” or “fire-resistance-rated” in Chapter 7 of the IBC.  Marked with a “W”, it and can be used as fire barriers in exit enclosures, exit passageways or horizontal exits to ensure that building occupants are protected from smoke, flames and dangerous radiant heat as they exit a burning building. In cases where evacuation is difficult or impossible (ex.