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.
It is not very long since the general scope of this branch of craftsmanship merely represented a tin-shop business on a large scale But as things are to-day, this is changed. From an enlarged tin-shop business, sheet-metal cornice work, including under that title every branch of architectural sheet-metal work, has become one of the substantial industries of the country, comparing favorably with almost any other mechanical branch in the building trades. Nor is this work confined to the larger cities. In the smaller towns is shown the progress of architectural sheet-metal work in the erection of entire building fronts constructed from sheet metal.
With the marked advancement of this industry, however, this need no longer be the case. A sheet-metal cornice is not now imitative. It possesses a variety and beauty peculiarly its own. No pattern is too complex or too difficult. Designs are satisfactorily executed in sheet metal which are impossible to produce in any other material
By the free and judicious application of pressed metal ornaments, a product is obtained that equals carved work. For boldness of figure, sharp and clean-cut lines, sheet-metal work takes the lead of all competitors
In order that there may be no misunderstanding as to the various parts contained in what the sheet-metal worker calls a "cornice,"
Fig. 255 has ben prepared, which gives the names of all the members in the "entablature" - the architectural name for what in the shop is known as the cornice. The term "entablature" is seldom heard among mechanics, a very general use of the word "cornice" having supplanted it in the common language of business.
An entablature consists of three principal parts - the cornice, the frieze, and the architrave. A glance at the illustration will serve to show the relation that each bears to the others. Among mechanics the shop term for architrave is foot-moulding; for frieze, panel; and for the subdivisions of the cornice, dentil course, modillion course, bed-mould, and crown-mould. In the modillion course, are the modillion-band and modillion-mould; while in the dentil course are the dentil-band and dentil-mould. Drips are shown at the bottom of the crown-and foot-mould fascias, and the ceiling under the crown mould is called the planceer. The edge at the top of the cornice is called a lock, and is used to lock the metal roofing into, when covering the top of the cornice. In the panel, there are the panel proper, the panel-mould, and the stile. The side and front of the modillion are also shown. Fig. 256 shows the side and front view of what is known as a bracket. Large terminal brackets in cornices, which project beyond the mouldings, and against which the mouldings end,are called trusses, a front and a side view of which are shown in Fig. 257. A block placed above a common bracket against which the moulding ends, is called a stop block, a front and a side view of which are shown in Fig. 258.
Fig. 259 is the front elevation of a cornice, in which are shown the truss, the bracket, the modillion, the dentil, and the panel. It is sometimes the case, in the construction of a cornice, that a bracket or modillion is called for, whose front and sides are carved as shown in the front and side views in Fig. 260. In that case, the brackets are obtained from dealers in pressed ornaments, who make a specialty of this kind of work. The same applies to capitals which would be required for plasters or columns, such as those shown in Figs. 261 and 262. The pilaster or column would be formed up in sheet metal, and the capital purchased and soldered in position. In Fig.
263, A shows an inclined moulding, which, as far as general position is concerned, would be the same as a gable moulding.
Raking mouldings are those which are inclined as in a gable or pediment; but, inasmuch as to miter an inclined moulding (as A) into a horizontal moulding (as B and C), under certain conditions, necessitates a change of profile, the term "to rake," among sheet-metal workers, has come to mean "to change profiles" for the accomplishment of such a miter. Hence the term "raked moulding" means one whose profile has been changed to admit of inhering.
The term miter, in common usage, designates a joint in a moulding at any angle.
Drawings form a very important part in sheet-metal architectural work. An elevation is a geometrical projection of a building or other object, on a plane perpendicular to the horizon - as, for example, Figs. 259 and 263. Elevations are ordinarily drawn to a scale of 1/4 or 1/2 inch to the foot. A sectional drawing shows a view of a building or other object as it would appear if cut in two at a given vertical line as, for example, Fig. 255. Detail drawings are ordinarily full size, and are often called working drawings. Tracings are duplicate drawings made by tracing upon transparent cloth or paper placed over the original drawing. Many other terms might be introduced here; but enough, we believe, have been presented to give the student the leading general points.
A few words are necessary on the subject of fastening the cornice to the wall.
Sheet-metal cornices are made of such a wide range of sizes, and are required to be placed in so many different locations, that the methods of construction, when wooden lookouts are employed and when the cornice is put together at the building in parts, are worthy of the most careful study. The general order of procedure in putting up, is as follows:
The foot-moulding or architrave a b (Fig. 264) is set upon the wall finished up to f, the drip a being drawn tight against the wall. The brickwork is then carried up, and the lookout A placed in position, the wall being carried up a few courses higher to hold the lookout in position. A board B is then nailed on top of the lookouts (which should be placed about three feet apart); and on this the flange of the foot-mould b is fastened. The frieze or panel b c is now placed into the lock B, which is closed and soldered; when the lookout C and the board D are placed in their proper positions, as before described.
The planceer and bed-mould c d are now locked and soldered at D, and the lookout E placed in position, with a board F placed under the lookouts the entire length of the cornice; onto this board the planceer is fastened. Having the proper measurements, the framer now constructs his lookouts or brackets G H I E, fastening to the beam at T, when the crown-mould d e is fastened to the planceer, through the flange of the drip at d, and at the top at c. The joints between lengths of mouldings, are made by lapping, riveting, or bolting, care being taken that they are joined so neatly as to hide all indications of a seam when finished and viewed from a short distance.
If brackets or modillions are to be placed in position, they are riveted or bolted in position; or sometimes the back of the cornice is blocked out with wood, and the brackets screwed in position through their flanges.
While a galvanized-iron cornice thus constructed on wooden lookouts will resist fire for a long time, a strictly fireproof cornice is obtained only by the use of metal for supports and fastenings, to the entire exclusion of wood. This fireproof method of construction is shown in Fig. 265. Instead of putting up in parts on the building, the cornice constructed in one piece in the shop or upon the ground, and hoisted to the top of the wall in long length easily handled. A drip a is used at the bottom of the foot-mould, and the joints made in the way indicated at b and c, with a lock at d. Band iron supports and braces are used, formed to the general contour of the parts as shown by A B
C, and bolted direct to the cornice, as shown, before hoisting.
When the cornice sets on the wall as at C, anchors are fastened to the main brace, as at D and E, with an end bent up or down for fastening. If the cornice sets perfectly plumb, the mason carries up his wall, which holds the cornice in a firm position. The top and back are then framed in the usual manner and covered by the metal roofer. In constructing cornices in this manner, the mouldings are run through solid, behind all brackets and modillions. The brackets and modillions are attached by means of riveting through outside flanges.