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.
A straight stringer is laid out by means of a pitch board, shown at (a) in Fig. 4. This board should be made of thin wood, with the grain parallel to the hypotenuse, so that the effects of shrinkage will be the least possible. The base is cut to equal the tread, and the perpendicular to equal the riser. At (b) is shown the stringer, as marked out for the steps ; the dotted line a b is drawn at a sufficient distance from the edge, so that the lower edges of the riser and tread will intersect on the line of the under side of the stringers, as shown at d. On the line a b, step off, with dividers, distance equal to the slope length of the pitch board. The latter may then be applied as shown, and its outline marked on the stringer edges. Templets, as shown at (c), should be made for the treads and risers, care being taken that the pitch in both cases is alike, so that the same shaped wedges can be used. The lines a d c b show the section of the tread, and a e f shows the shape of the wedge. The tread and riser templets, when applied to the stringer, should have their outer edges coincide with the lines made from the pitch board, giving the outline shown at 5.
To form the housing, holes are bored in the stringers adjacent to the nosing of the tread, as at c, and that portion is removed by means of a chisel. The lines of the templets may then be cut to the depth of the groove by a saw, and the material removed with a router plane.
Such a stringer is shown in Fig. 5, with the exception that the under edge is kept somewhat lower than the point a in Fig. 4, and is preferable to the latter method in that the wedges arc well supported at their outer ends. If the stair-case will allow the insertion of the assembled parts, the treads and risers arc attached to the stringers, wedged, and glued into the housing, and the whole taken bodily to its place in the building. The wedges are shown in place at b and b, Fig. 5.
The wall stringer, as shown in Fig. 6, and also the front stringer, it" a close one, are each grooved as already explained, the depth depending upon the thickness of the stringer. Two or more carriage timbers are used in the width of the stairway, the number, depth, and thickness depending on the width of the stairway and the load to be carried.
The front stringer, as shown in Fig. 7, is well nailed to the front carriage timber a, while the other timbers are rough bracketed under each step alternately on the sides, and nailed as shown at a, Fig. 2. A furring strip is nailed to the wall in line with the lower edge of the carriage timbers, to receive the lath.
The prepared mortised wall stringer is nailed to the wall to square properly with the previously set carriage timber and front stringer.