The partitions of fireproof buildings may be built of brick, terra-cotta, tiles, or plaster blocks, or of light iron studding with metal lathing and plaster. Brick partitions, to resist the passage of fire, must be at least twelve inches thick, and so are not generally used unless required for floor bearing also. With the column and girder construction which we have had under consideration, a lighter construction than brick is generally desired for partitions.

Fig. 234. Terra Cotta Girder Casing.

Fig. 234. Terra-Cotta Girder Casing.

Fig. 235. Lath and Plaster Girder Casing.

Fig. 235. Lath and Plaster Girder Casing.

Partition Blocks, Terra-cotta blocks, either of dense or porous terra cotta, make a very good partition; these are usually made four inches thick, and are of the same composition as the floor blocks. They are usually set with the hollows running horizontally, in order to obtain the flat surface for bedding, but where it is necessary to cut for vertical pipes, it is well to set a vertical line of blocks on end and clamp them to the flat tiles. All openings for doors and windows are framed with wooden studs (or with steel bars, if the door frames are of cast iron) to receive the frames and finish. (Fig. 236.) For thinner partitions, blocks of solid porous terra cotta two inches thick may be used, but they must be clamped or banded together. A patented partition may be obtained of thin terra-cotta plates reinforced by twisted steel wires run on either side of the plates and embedded in the plaster. Thin plates having plaster of Paris for a base, and clamped or banded with iron, are also used for partition blocks where extra lightness is required.

For all of these blocks, mortar composed of lime with a little cement should be used for setting, and the finished plaster surfaces are best when hard-setting plaster is used.