19.8
which holds together against flame for a considerable period of time, is usually required in windows that face a nearby structure. Several substitutes for wired glass have become available in recent years, including a fire-resistant transparent ceramic that stays intact at high temperatures. In multistory buildings, fire on a lower floor can spread to upper floors by crawling up the face of the building floor by floor, breaking windows and igniting combustible materials inside. Two alternatives are open to the designer to solve this problem: a fire-resistant spandrel at least 3 feet (914 mm) high may be provided or else a horizontally projecting flame barrier, also made of fire-resistant materials, at least 30 inches (762 mm) wide (19.10).
19.9
19.10
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