Building fires are not hot enough to melt steel, but are often able to weaken it sufficiently to cause structural failure. For this reason, building codes generally limit the use of exposed steel framing to buildings of one to five stories, where escape in case of fire is rapid. For taller buildings, it is necessary to protect the steel frame from heat long enough for the building to be fully evacuated and the fire extinguished or allowed to burn out on its own. Fireproofing of steel framing was originally done by encasing steel beams and columns in brick masonry or poured concrete. But, this added, in turn, the weight and cost of the frame. The search for lighter-weight fireproofing led first to thin enclosures of metal lath and plaster around the steel members.
Methods for fireproofing steel columns :
a) Encasement in reinforced concrete
b) Enclosure in metal lath and plaster
c) Enclosure in multiple layer of gypsum board
d) Spray-on fireproofing (spray-applied fire-resistive materials (SFRM))
e) Loose insulating fill inside a sheet metal enclosure
f) Water-filled box column made of a wide-flange shape with added steel plates
Methods for fireproofing steel beams and girders :
a) Encasement in reinforced concrete
b) Enclosure in metal lath and plaster
c) Rigid slab fireproofing
d) Spray on fireproofing
e) Suspended plaster ceiling
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