In construction, heavy wood timbers have a relatively high fire resistance, because fire tends to burn very slowly inward from the surface, leaving enough sound timber in the center to prevent collapse. Wood framing can also be impregnated with ammonium phosphate solution or covered with special mastics. Stucco or other incombustible facing also gives a wood frame some protection from fire. Structural steel may be protected in a number of ways. A protective layer of concrete over all surfaces of a beam or over the steel bars in reinforced concrete has to be at least 2.5 in.
Some recent buildings circulate water inside each column, protecting the structure against meltdown.
Concrete is still used, but mostly as a thin slab on floors. Standards for fireproofing are set by organizations such as the American Insurance Association and the International Conference of Building Officials. The Columbia Encyclopedia, Sixth Edition. Click here to shop the Bartleby Bookstore .