151. As the materials made use of in modern fireproof construction, to protect the structural parts of buildings from fire and heat, come within the province of the architect, a good knowledge of the systems and methods in use is necessary for the intelligent design and direction of the work.

Probably the nearest approach to an absolutely fireproof structure is a building constructed entirely of brick and terra cotta, with tile or brick arched floors, and vaulted roof, so that no iron or wood is needed for structural purposes. Such a building, if large, would naturally need thick walls and massive piers, occupying considerable space. The value of land in large cities requires the utmost economy of space, and for this reason the columns in a business structure must be as few and as far apart as consistent with safety, and the distance between the ceilings and the floor above must be as little as possible. Such conditions necessitate the use of some stronger and less bulky materials, such as iron and steel, protected in some manner from direct exposure to fire or heat.

Buildings having wooden posts, beams, etc., are rendered fireproof almost entirely by plaster laid on metal lathing, or with plaster boards or blocks; these methods will be described under "Plastering."

152. Before the plans for the building are made, the material and method of construction to be used should be decided on, as some of the fireproof systems require particular arrangement and shape of the supporting members.

The principal fireproof materials are brick, terra-cotta tiles, and concrete, the latter being bound together and strengthened by steel bars, wire, or netting. Nearly all methods of fireproofing are covered by patents owned by large manufacturing concerns, which, usually, will undertake to supply and set all the fireproof material used in a building. This plan is productive of much better results than when the work is done by inexperienced contractors.