319. Partitions

The partitions in fireproof buildings should be built either of brick, tile or iron studding, covered with metal lath and plaster. Brick partitions, when not less than 12 inches thick, may be considered as fireproof, but they are now seldom used except where they can be utilized to support the floors.

In the modern fireproof office building, hotel or apartment house the floors are supported, except at the walls, entirely by columns and girders, and the partitions are almost universally constructed either of hollow tile, or of thin, solid porous tiles, or metal lath and plaster. Hollow tile are probably the most extensively used for this purpose, although "thin" partitions (from 1 to 2 inches thick) are coming into quite general use in office buildings.

319 Partitions 100215

Fig. 200.

Partition tiles are made of the same materials and possess the same characteristics as those used in floor construction. Both dense and porous tiles are used for this purpose, porous tiles probably the most extensively, owing to their property of receiving and holding nails.

Partition tiles are made in thicknesses varying from 2 to 6 inches, but the 4-inch blocks are most commonly used. The tiles are generally 12x12 or 6x12 inches on the face. They may be set with the hollows running vertically or horizontally, either construction being sufficiently strong; the horizontal construction, however, has the advantage of a better bonded mortar joint. When the tiles are laid vertically they are frequently clamped together; when laid horizontally a certain number of tile should be set vertically to accommodate the gas pipes. When the latter are located before the partitions are set the tile may be cut and built around the pipes, or special recessed tile may be used, as shown in Fig. 201. Whether laid vertically or horizontally, the blocks should always be set so as to break joint with each other.

For setting the tiles or blocks, lime mortar, to which a small proportion of natural cement is added, is generally used. Acme cement plaster has recently been used for this purpose with excellent results, as it adheres to the tiling even better than natural cements.

At all openings in partitions rough wood frames are set, as shown in Fig. 202, to stiffen the jambs and to afford grounds for the plaster and nailings for the finished frames and casings.

If dense tiles are used for the partitions it is necessary to build in wooden bricks or -inch strips in the horizontal or vertical joints to form nailings for the base, chair rail and picture moulding, or courses of porous tiles may be inserted at these places. When porous tiles are used the wood blocks or strips are generally omitted, although experience has shown that porous tiles do not hold the nails quite so securely as wood.

Hollow tile partitions are generally laid on top of the finished floor if there is the least likelihood of their ever being taken down, and, as they are not fastened in any way to the floor or ceiling, they can very easily be removed or changed to suit tenants.

The weight of hollow tile partitions per square foot, plastered both sides, will average as follows :

319 Partitions 100216

Fig. 201.

319 Partitions 100217

Fig. 302.

3-inch

dense tile.........

27

pounds.

4-inch

dense tile.........

29

pounds.

5-inch

dense tile.........

32

pounds.

6-inch

dense tile.........

36

pounds.

3-inch

porous tile.....

pounds.

4-inch

porous tile.....

29

pounds.

5-inch

porous tile.....

35

pounds.

6-inch

porous tile.....

•39

pounds.