Fighting Fire With...Other Things
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Fighting Fire With.. .Other Things In an effort to prevent the spread of fire within individual buildings and through cities, laws dictating the choice of certain building materials, construction assemblies, and urban configurations have developed. Fire behaves in complex ways and propagates according to the fuel, oxygen, and pathways available. To prevent a building from burning down, or to at least buy time to allow occupants to escape, designers have chosen nonflammable materials, employed means of protecting flammable components, delayed the effects of fire on noncombustible materials, and blocked pathways along which fire might spread. In addition to whether or not a building element will burn, designers consider how it behaves as temperature increases: does it melt? does it lose its ability to bear weight? does it fail gradually or catastrophically? London recorded great conflagrations in 798, 982, and 1086. In 1189, to reduce the danger of fire, Fitz-Ailwyne's Assize was put into effect. London's buildings in the 12th century were built primarily of wood, with straw or reed roofs. The edict provided privileges to those who built stone houses with clay tile roofs, and has been referred to as the earliest English Building Act. In 1212, London suffered a great fire that prompted the limitation of various building uses and revisions to the Assize. The reinforced Assize strictly forbade any roofing materials but clay tiles, shingle boards, or lead. This did not, however, prevent houses with flammable wood structures from being built in the succeeding centuries. In 1666, London suffered The Great Fire, which destroyed 80% of the city. In response, the city plan was redesigned by Sir Christopher Wren to provide a rational street system and further laws were enacted which governed the way in which buildings were built. Half-timbered buildings, which used highly combustible pitch to seal cracks, significantly contributed to the fire. Parliament's Act for Rebuilding the City of London stipulated that the exterior walls of all houses be built of brick or stone, with exceptions for incidental elements such as doors and window frames. Many of the principles contained in those edicts are still relevant and remain in force in some current building codes, for example, the requirement that party walls between buildings continue through the roof. Until the 19th century, prescriptive strategies were used to avoid the spread of fire. To put out a fire, the choices were water or smothering. With the development of the steel building frame in the MRS BULLETIN/SEPTEMBER 1998
United States and Europe in the mid-19th century, a new, noncombustible building material came into play. The Chicago Fire of 1871, for example, prompted the largest early efforts to use recently developed materials—in this case, the steel building frame—in a strategic way to prevent losses by fire. As technological advances permitted larger buildings to be built, escape provisions for crowds became a commonplace issue, especially, for example, in theaters or
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