Platform stairs are often constructed so that one flight will run in a direction opposite to that of the other flight, as shown in [Fig.35]. In cases of this kind, the landing or platform requires to have a length more than double that of the treads, in order that both flights may have the same width. Sometimes, however, and for various reasons, the upper flight is made a little narrower than the lower; but this expedient should be avoided whenever possible, as its adoption unbalances the stairs. In the example before us, eleven treads, not including the landing, run in one direction; while four treads, including the landing, run in the opposite direction; or, as workmen put it, the stair “returns on itself.” The elevation shown in [Fig. 36] illustrates the manner in which the work is executed. The various parts are shown as follows:
Fig. 35. Plan of Platform Stair Returning on Itself.
[Fig. 37] is a section of the top landing, with baluster and rail.
[Fig. 38] is part of the long newel, showing mortises for the strings.
Fig. 36. Elevation Showing Construction of Platform Stair
of which Plan is Given in [Fig. 35].