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are called by various trade names such as "Ferro-Domes”, “FloreDomes”, “Floretyles”, etc.
Advantages of Different Types. With many types of flooring available, each possessing merits peculiar to its own construction, the architect is often at a loss to decide upon a special system. Cost, which is an ever-present factor, will decide in many cases, and in others local considerations may require particular methods. In the main, regard should be given to lightness, strength, and fireresisting qualities, as well as to speed of erection and the skill of available workmen.
Of the respective merits of the two general systems of terra cotta and concrete, much has been written, especially with regard to fire-resisting qualities, but the question of the advantage of one over the other cannot be said to have been settled at the present time. For the very high buildings, one of the systems requiring the use of riveted steel floor beams and girders is usually adopted, the beams spaced not only with reference to the load and the requirements of the floor construction, but with a regard to the general strength and stability of the whole building.
Fireproofing. The various parts of a building of steel construction are in themselves of a fire-resisting character, but for the thor
ough protection of the structure, special devices must be employed.
Columns. Especially is this true in the case of col
umns, which must sustain great Fig: 240. Terra Cotta Fig. 241. Lath and Plas- weight and should, therefore,
be adequately protected. Columns may be enclosed in concrete or brick, which should be not less than 8 inches thick; or hollow terra cotta tiles may be used, preferably in two layers, each not less than 2 inches thick and breaking joints, Fig. 240. Columns may also be partially protected by the use of metal lathing and plaster in one or two layers with an air space between, Fig. 241.
Floors. Floor beams and girders are protected normally by the floor or ceiling construction, and each maker of floor construction has his own system of fireproofing for girders and columns and
ter Column Casing
other exposed members, so that, in general, the contractor for the floors will be given a contract for all the other fireproofing in the building.
ROOF AND WALL CONSTRUCTION Roofs and Ceilings. As the roofs of high buildings are generally made with very little pitch, the same construction may be used here as for the floors, but a special treatment will be required to retain a level ceiling in the upper story. This is usually done by hanging steel T-bars at a level
at a level IJINSI below the roof, upon which a ceil- Fig. 242. Hanging of Terra Cotta Ceiling ing may be laid either of terra cutta blocks to be plastered, Fig. 242, or of metal lathing, Fig. 243.
Exterior Walls. The construction of the exterior skeleton of a fireproof building varies according to the covering material. While the adopted type of floors may be carried throughout one or several buildings, by a simple repetition of methods, the construction of the outside frame must be modified to suit the different materials used in different buildings, or often in different portions of the same building.
The exterior treatment of a building of skeleton construction may be said, in general, to resolve itself into a series of piers, more or less marked in Fig. 9 character, which enclose the vertical supports, the space between them being to a great extent occupied by windows, while a horizontal piece of masonry separates the windows of each story and covers the floors.
The masonry enclosing the building is generally supported by the steel frame, and may be of brick or stone, according to design, though concrete and terra cotta in molded or cast forms are also available.
Terra Cotta Covering. The adaptability of terra cotta to the exterior adornment and fireproofing of buildings is so great that its
Fig. 243. Hanging of Wire Lath
use has become general in all places where durability and resistance to heat are essential. The ornamental facings cannot always be supported by direct bearing on the steel frame, and so a system of
anchors and ties must be devised by which the separate blocks may be held in place.
For terra cotta finish which has no great projection from the line of support, ties of 4-inch rods may be hooked into the ribs of the terra cotta and secured to the steel frame or the brick filling, Fig. 244; but when a greater projection is required, as for cornices, then small beams or T-irons must be used, well built-in or
anchored to the main structure, Fig. 245. Fig. 244. Section Showing Method Exterior terra cotta as ordinarily finished
. is not affected by the atmospheric conditions which affect stone; but as the surfaces are likely to become warped in the baking, it is necessary to see that no attempt is made to straighten bad pieces by chiseling, as this destroys the surface and exposes the softer interior to the danger of decay.
of Anchoring Terra Cotta
PARTITIONS 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 12 inches thick, and are not, therefore, 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.
Partition Blocks. Terra cotta
blocks, either of dense or porous terra Fig. 245. Section of Terra Cotta
cotta, make good partitions, Fig. 246; these are usually made 4 inches thick, and are of the same composition as the floor blocks. They are generally 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 made with wooden studs (or with steel bars, if the door frames are of cast iron) to receive the frames and finish. For thinner partitions, blocks of solid porous terra cotta 2 inches thick may be used, but my they must be clamped or banded together. A patented partition may be obtained of Fig. 246. Terra Cotta Bloc thin terra cotta plates, reinforced by twisted steel wires run on either side of the plates and imbedded 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.
Metal-Lath Partitions. To save floor space, very thin parti. tions may be made by using small steel bars for studding; these are usually 2-inch channel bars set vertically about a foot apart and turned at a right angle to be fastened top and bottom. On one side metal lathing is stretched and wired to the bars. This is covered with a very heavy coat of hard plaster, which squeezes through the lathing and makes a good surface to receive the plaster of the other side of the partition, the whole forming, when completed, a solid wall of plaster and metal about 11 inches thick, Fig. 247. It is necessary in this case to use a very hard-setting plaster, as this gives the partition its stiffness. Special patented studs of sheet steel, made with prongs to hold the lathing, and of various depths, Fig. 248, are used in
Strometne a similar manner. Door and
Fig. 247. Section of Steel and Lath Partition window frames are placed in these thin partitions by setting up a rough wooden frame to which the channel bar is screwed, as in Fig. 249, and as a nailing for chair rails, picture moldings, and other finish, strips of wood are laced to the lathing, flush with the plastering, before the plaster is applied, Fig. 250.
Metal Lathing. Metal lathing, which is of great importance both for fireproofing, and for the finishing of fireproof buildings, may
be obtained in a variety of patterns and devices.
Wire Cloth. The original metal lathing was the common wire cloth, and this is still one of the principal forms in which it is found. Improvement in the manufacture of wire cloth has been made by stiffening the cloth in various ways by the use of rods or ribs of
metal. These are attached to, or woven into, the lathFig. 248. ing which is then known as stiffened lathing. Steel Stud "
Clinton Lath. A well-known form of stiffened lathing is the Clinton lath, which contains corrugated steel furring strips, attached to the cloth by metal clips and running across the roll every 8 inches. These strips not only serve to stiffen the
lathing when stretched over furrings, but, if the lathing is applied directly to a plain surface, such as planking or brick walls,
the stiffening keeps the lathing away, and Fig. 249. Door Finish in Thin
gives room for the clinch of the plaster.
Roebling Lath. The Roebling stiffened lathing contains V-shaped ribs of various depth, which are woven into the cloth at 74-inch intervals. These ribs serve for a furring, and are made from š to 14 inches in depth. For special uses, ribs of 2-inch steel rods are used instead of the V-shaped steel. Wire
cloth for lathing is run in a variety of meshes, 3X3 and 21x21 to the inch being the common meshes, and they may be obtained plain, painted, or galvanized. Painted lathing is very satisfactory, and is more generally used than any other kind.
Expanded-Metal Lath. This form of lathing is made from strips of thin and tough sheet steel,
which are cut at regular intervals and then "exFig. 250. Wood
panded” by being wrenched or pushed into open
meshes, large or small as the cuts are made long or short. This expanding also turns the metal on edge, making a flat and stiff sheet of lathing much larger than the original piece of metal, Fig. 251. Having a degree of stiffness, this lathing does not require stretching, and it is used extensively for wrapping
Furring in Thin