This section is from the book "A Treatise On Architecture And Building Construction Vol3: Stair Building, Ornamental Ironwork, Roofing, Sheet-Metal Work, Electric-Light Wiring And Bellwork", by The Colliery Engineer Co.. Also available from Amazon: A Treatise On Architecture And Building Construction.
14. Stairways in public buildings should be of iron, and by reason of the prominence of their location it is usually necessary that their design should be in accordance with their surroundings. A number of stairways are herein shown, not to give a variety of examples, but to illustrate the different conditions that are likely to arise in building. Any of these designs may be stripped of its ornament and be used in the plainest of structures, or the ornament may be increased and the design made suitable for a most elaborate interior. The stairs shown in Fig. 12 are suitable for such use as a basement stairway, or in a place where two floors are leased or used by one occupant, and a communication between them is necessary independent of the public halls and stairs.
15. In laying out the drawings for this flight of stairs, locate the center line of the newel d one inch from the face of the beam e, and the face of the last riser at the center of the newel, and from this riser measure off 15 times 10 inches, or 150 inches (there being 15 treads), which will be 12 ft. 6 in., and there locate the position of the face of the first riser. The framed opening of the well through which the stair is raised is more than the length of the stair, so that the headroom does not necessarily have to be considered. The width of the opening is 3 feet, and the strings f must not be more than that distance apart over all. The rise, the tread, and the position of the newel, the first and the last riser, and the width of the opening being fixed, a plan, as at (b), should be laid out, then the section (a), which shows the inside face of the string which finishes against the newel. The outer string should be similarly laid out. The next point to consider is the finish of the well; this, as shown in the section (a), has a molded facia j, a light hand rail of wood, and a balustrade of wrought iron composed of 3/4-inch square balusters with a top and a bottom rail, and two additional rails forming a frieze and dado through which the balusters pass, making a very stiff rail. The moldings on the facia j are so placed that they come inside the face of the wall string, as shown at f, against which they abut. The newel g and the end rail are set 1 1/4 inches from the flange of the beam h. These points fixed, the general layout is complete and the next procedure is to make the several parts in detail.
16. The first piece to detail is the string f, the sectional shape of which is shown at i, Fig. 13 (c). The lug k is cast on the string, and supports the ends of the treads. The heads of the strings are cast with the base or lower part of the newel on them, and are shown in plan at d, Fig. 13 (b), and in section and elevation at (a). The plan (b) shows a lug l cast on the back of the newel which holds the string in place, and is secured to the flange of the beam with a hexagonal-headed bolt; the lug m is cast on the inside of the newel to receive the last riser. The stair strings are stiffened and anchored to the walls by the plate and brace device shown at u in Fig. 13 (c), and are set sufficiently far from the wall to receive the plaster or other finish at top and bottom. At o and p, Fig. 13 (a), a small allowance is made for any variation that might arise, thus enabling the erectors to raise or lower the stairs a fraction of an inch in case of necessity.
The angle newel is secured to the beam in the same manner as the newel d, and is cast with two lugs, so as to receive both the end and the side facias. These facias are cast with ribs r [see Fig. 13 (c)], along the back 2 feet apart, in order to stiffen and support them. The facias are held in place by wrought-iron anchors s to which they are bolted with hexagonal-headed bolts, which enable the erector to use a wrench in this close place.
17. The newels are cast with the upper part of each separate. A wrought-iron rod runs through the base and the shaft of the newel, the lower end passing through a plate in the base, and the upper end through a plate in the head of the shaft; the newel is thus held firmly together when the nut is screwed on. The caps of the newels are cast with a shoulder and secured to the newel with countersunk screws. The lower rail of the balustrade is secured to the facia with countersunk screws, and the upper rail in the same manner to the newel.
In Fig. 14 is shown one of the risers, which, except the top one, are all alike. The flange v in the section is cast on the lower edge, and receives the marble or slate tread, and the nosing w is extended at the back to give a bearing for the tread. At x is a check, in which the lug of the string fits. The upper riser of the flight differs from all the others, as it must be wide enough to form a facia and finish under the stairs, as shown at n in Fig. 13 (a), and at the same time provide a stop for the plaster of the ceiling. The method of casting is not described, as it is perfectly plain work.