199. Fireproof partitions are usually made of tile, or wire lathing or plaster, although brick and iron are used to some extent. The objection to brick is that it must be at least 1 foot thick in order to be thoroughly fireproof, and this causes unnecessary weight. If iron is used, it must be well protected. If the partitions are of tile, they are quite thin and light, and may be readily removed and set up elsewhere, to suit the requirements of tenants. The tile may be either of the dense hollow, or porous kind, and may vary from about 1 1/2 inches to 6 inches in thickness; the usual thickness, however, is 4 inches, with face dimensions of 6 in. X12 in., or 12 in. X 12 in. Porous tile are preferable on account of their greater fire-resisting qualities, and also because they hold nails well; with dense tile, wooden nailing strips are necessary. If the tiles are hollow, they may be laid with the voids extending vertically or horizontally. If laid in the former way, the tiles are usually tied together by clamps, as the mortar joint is not very effective. If set horizontally, the mortar is spread over a much larger surface and makes a better joint. The blocks are usually set in lime mortar containing about 1/4 part of cement. "Acme " cement plaster is also considerably used, as it sets quickly and adheres well to the blocks.

Fireproof Partitions 224

Fig. 96.

200. Special recessed tile are provided to receive the pipes which it is necessary to run along the partitions. These are shown in Fig. 97, in which a shows the ordinary tile, and b the special tile, grooved to permit the insertion of pipe c.

Fireproof Partitions 225

Fig. 97.

Wherever doors or other openings come in the partitions, as shown in Fig. 98, the tile b abuts rough wood frames a, to which the finished casings c are nailed.

201. When extremely thin partitions are required, they are usually made of very small angles or beams, to which is attached wire or expanded metal lath. Porous terra cotta, in pieces 2 inches thick, is also used, being bound together by metal clamps, and similarly attached to the floor and ceiling. In another form, the blocks are held in place on both sides by light steel rods, which are fastened at the ends, and enclosed throughout their length by the plaster. For rooms under 13 feet in height, the last mentioned partition is only 2 inches thick, increasing to 4 inches for a height of 20 feet. Another kind of thin partition is made on the principle of the Ransome floor, of concrete, supported and stiffened by twisted bars, as described in "Concrete Construction."

Fireproof Partitions 226

Fig. 98.

202. The average weight of hollow tile partitions, including plastering on both sides, is from 27 to 36 pounds for 3 to 6 inch thick dense tile, and from 2-1 to 39 pounds for the same thickness of porous tile.

203. Wall Pairings

Wall Pairings. Basement walls of fireproof buildings are generally protected by hollow tile. The method of laying these will be found under "Terra-Cotta Furring," in Masonry, § 7.