n.
Use of fire-resistant materials in a building to prevent structural collapse and allow safe egress of occupants in case of fire.
The fire-resistive ratings of various materials and constructions are established by laboratory tests and usually specified in terms of hours a material or assembly can be expected to withstand exposure to fire. Building codes require application of cementitious material or insulation to structural steel frames, fire-resistant construction (e.g., using concrete block) of enclosures around exits, flame-spread ratings of finish materials such as carpeting and wall coverings, and use of such inherently fire-resistant materials as reinforced concrete and heavy timber.