This section is from the "Architectural Iron And Steel, And Its Application In The Construction Of Buildings" book, by WM. H. Birkmire.. Also see Amazon: Architectural Iron And Steel, And Its Application In The Construction Of Buildings.
Galvanized Iron Cornices are made of No. 22 to No. 28 gauge galvanized sheet iron, 22 being the heaviest. Mouldings of all sizes and shapes are soldered together, the ornamental work made of zinc, either cast or pressed in various designs. When a large cornice is placed on a front extending above the roof, the framework is made of wrought iron, usually constructed as shown, the framework to take the heaviest portion of cornice. The section at C is the wall of a front; A is a 3 X 3-inch angle-iron frame secured to roof.
B is the same covering as applied to roof surface of building. If the wall is built before the cornice is ready, a recess should be left in brickwork across front, 3 inches deep by 3/4 of an inch high. But a more satisfactory method, and one insuring greater rigidity, is to set the lower portion of cornice on wall at the proper height and build in the anchor straps, filling the masonry in and around the anchorage as much as possible.
The scuttle opening on roof is formed by a cast-iron curb at A (see plate, page 132), 1/2 inch thick, and secured to beams with 1/2-inch bolts, the curb to be at least 8 inches above roof and from 2 by 2 feet to 3 by 4 feet in size. It should be covered with a sheet-iron door of No. 16 gauge, with 1 1/4X 3/8-inch frames, hinged and bolted on inside.8
The lattice door at bottom of curb is made of 1 X 1/4-inch flats resting on top of each other and riveted. If made of 1/16 or1/8 inch flats they can be interlaced. This door folds outwards into curb, serving as a protection against ingress to building when outer door is open for ventilation, etc. The doors are secured on the inside to ladder by a padlock or chain and padlock.
Scuttle Ladder is placed at the entrance to scuttle, and is made of 3 X 1/4-inch flat iron, for the sides, and 1/2-inch double rungs, 12 inches in rise. The width of ladder 20 inches from outside to outside of sides. To be secured to floor, and beams above, by 3 X 2 X 1/4-inch knees.
In buildings where wooden beams are used, the scuttle doors and curbs are also made of wood, and covered with No. 16 sheet iron. The lower door is fastened to curb by an angle-iron frame 1 1/4 X 1 1/4 X 1/4 inch thick.
Cast-iron for fronts has many advantages in its favor - strength, lightness of structure, facility of erection, durability, economy and incombustibility. Previous to their erection in the building for which they are intended, the columns, mullions, sills, soffits and fascias are fitted together complete at the works.
Iron is cheaper and more durable than any other material for fronts; and whatever mouldings, carvings, etc., are appropriate for stone, brick and terra cotta, are also suitable for iron. In business quarters blocks of stores are built up solid with iron fronts.
Light being one of the principal requirements, a front of iron may be safely used in place of the bulkier constructions of other material; as, while ample strength is secured, it allows freer admission of light.
In the most costly buildings erected at the present day cast iron is largely used for enclosing the fronts between piers, for mullions and fascias in bay-windows, fascias under windows, and for ornamentation where richness of design is desired. For the latter it serves a valuable purpose, as ornate effects may be produced whose cost in stone or other material would prove prohibitive.
The space in this volume not admitting of the full details for an entire front, only a portion of an ordinary front is shown.
The principal bearing columns must first be taken into consideration. These generally carry the girders, which extend at right angles to the front by brackets cast on the back.
The bearing columns should be continuous from foundation stone or piers to top of front, and connected at each story level by flanges as shown at C. To brace the columns on sides, cast-iron lintels (A) or beam girders are used, bolted to column and resting on bracket B. The cornice, sill E, soffit above door, and fascia cover the above connecting flanges.
The cast-iron lintel is also used to support a brick wall 12 inches thick which should be built to fill in cornice.
Many fronts have the columns sufficiently large to allow the backs open, with bridge pieces across, and the column filled with brickwork.
The section of front herein shown is taken through the doorway. D is the cast-iron transom, H the sill, with riser G and patent light sidewalk.
In the plan K represents an open-back column. The cornice work and fascias should be cast 1/4 of an inch thick, and supported by cast-iron brackets resting on and secured to lintels.