STAIR-BUILDING Introductory. In the following instructions in the art of Stair building, it is the intention to adhere closely to the practical phases of the subject, and to present only such matter as will directly aid the student in acquiring a practical mastery of the art.
Stair-building, though one of the most important subjects con nected with the art of building, is probably ihe subject least under stood by designers and by workmen generally. In but few of the plans that leave the offices of Architects, are the stairs properly laid down; and many of the books that have been sent out for the purpose of giving instruction in the art of building, have this common defect— that the body of the stairs is laid down imperfectly, and therefore presents great difficulties in the construction of the rail.
The stairs are an important feature of a building. On entering a house they are usually the first object to meet the eye and claim the attention. If one sees an ugly staircase, it will, in a measure, condemn the whole house, for the first impression produced will hardly afterwards be totally eradicated by commendable features that may be noted elsewhere in the building. It is extremely important, therefore, that both designer and workman shall see that staircases are properly laid out.
Stairways should be commodious to ascend—inviting people, as it were, to go up. When winders are used, they should extend 'last the spring line of the cylinder, so as to give proper width at the narrow end (see Fig. 72) and bring the rail there as nearly as possible to the same pitch or slant as the rail over the square steps. When the hall is of sufficient width, the stairway should not be less than four feet wide, so that two people can conveniently pass each other thereon. The height of riser and width of tread are governed by the staircase, which is the space allowed for the stairway; but, as a general rule, the tread should not be less than nine inches wide, and the riser should not be over eight inches high. Seven-inch riser
and eleven-inch tread will make an easy stepping stairway. If you increase the width of the tread, you must reduce the height of the riser. The tread and riser together should not be over eighteen inches, and not less than seventeen inches. These dimensions, however, cannot always be adhered to, as conditions will often compel a devia tion from the rule; for instance, in large buildings, such as hotels, railway depots, or other public buildings, treads are often made 18 inches wide, having risers of from 21 inches to 5 inches depth.
Definitions. Before pro ceeding further with the subject, it is essential that the student make himself familiar with a few of the terms used in stair-building.
The term rise and run is often used, and indicates certain dimensions of the stairway. Fig.
1 will illustrate exactly what is meant; the line A B shows the run, or the length over the floor the stairs will occupy. From B to C is the rise, or the total height from top of lower floor to top of upper Boor.* The line D is the pitch or line of nosings, showing the angle of inclination of the stairs. On the three lines shown—the run, the rise, and the pitch—depends the whole system of stair-building.
The body or staircase is the room or space in which the stairway is contained. This may be a space including the width and length of the stairway only, in which case it is called a close stairway, no rail or baluster being necessary. Or the stairway may be- in a large apartment, such as a passage or hall, or even in a large room, openings being left in the upper floors so as to allow road room for persons on the stairway, and to furnish communication between the stairways and the different stories of the building. In such cases we have what arc known as open stairways, from the fact that they are not closed on both sides, the steps showing their ends at one side, while on the other side they are generally placed against the wall.