This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
For terra-cotta finish which has no great projection from the line of support, ties of one-quarter inch rods may be hooked into the ribs of the terra cotta and secured to the steel frame or the brick filling, as in Fig. 230, but when a greater projection is required, as for cornices, small beams or T-irons must be used, well built in or anchored to the main structure, as in Fig. 231. Exterior terra cotta as ordinarily finished is not affected by the atmospheric conditions which affect stone; but as the surfaces are liable to become warped in the baking, it will be necessary to see that no attempt is made to straighten bad pieces by chiselling, as this destroys the surface and exposes the softer interior to decay.
Fig. 230. Anchoring of Terra Cotta.
Fig. 231. Terra-Cotta Cornice.
We have thus far considered the covering of the steel skeleton from the point of obtaining an available floor surface, and the necessary housing in by means of the exterior walls. While these elements are also made to serve their turn in protecting the frame from fire and the elements, further and complete protection from fire must be considered as of prime importance.
Especially is this true in the case of the columns, which necessarily sustain a great weight, and should therefore be adequately protected. Columns may be enclosed in brick, which should be not less than eight inches thick, or hollow terra-cotta tiles may be used, preferably in two layers, each not less than two inches thick and breaking joints. (Fig. 232.) Columns may also be protected by the use of metal lathing and plaster in one or two layers with an air space between. (Fig. 233.)
While the floor beams and flush girders are protected normally by the floor or ceiling construction, girders which drop below the floor must be given a special protection. This may be of porous terra-cotta blocks, shown in Fig. 234, or of metal lathing and plaster, Fig. 235.
Fig. 232. Terra-Cotta Column Casing.
Fig. 233. Lath and Plaster Column Casing.
The makers of floor construction have each their own system of fireproofing of girders and columns and other exposed members, and, in general, the contractor for the floors will be given a contract for all the other fireproofing of the building.