250. - Stairs: General Requirements. - The STAIRS is that commodious arrangement of steps in a building by which access is obtained from one story to another. Their position, form, and finish, when determined with discriminating taste, add greatly to the comfort and elegance of a structure. As regards their position, the first object should be to have them near the middle of the building, in order that they may afford an equally easy access to all the rooms and passages. Next in importance is light; to obtain which they would seem to be best situated near an outer wall, in which windows might be constructed for the purpose; yet a skylight, or opening in the roof, would not only provide light, and so secure a central position for the stairs, but may be made, also, to assist materially as an ornament to the building, and, what is of more importance, afford an opportunity for better ventilation.
All stairs, especially those of the most important buildings, should be erected of stone or some equally durable and fire-resisting material, that the means of egress from a burning building may not be too rapidly destroyed.
Winding stairs, or those in which the direction is gradually changed by means of winders, or steps which taper in width, are interesting by reason of the greater skill required in their construction; but are objectionable, for the reason that children are exposed to accident by their liability to fall when passing over the narrow ends of the steps. Stairs of this kind should be tolerated only where there is not sufficient space for those with flyers, or steps of parallel width.
Stairs in one long continuous flight are also objectionable. Platforms or landings should be introduced at intervals, so that any one flight may not contain more than about twelve or fifteen steps.
The width of stairs should be in accordance with the importance of the building in which they are placed, varying from 3 to 12 feet. Where two persons are expected to pass each other conveniently the least width admissible is 3 feet. Still, in crowded cities, where land is valuable, the space allowed for passages is correspondingly small, and in these stairs are sometimes made as narrow as 2 1/2 feet.
Khorsabad. - Assyrian Temple, Restored.
From 3 to 4 feet is a suitable width for a good dwelling; while 5 feet will be found ample for stairs in buildings occupied by many people; and from 8 to 12 feet is sufficient for the width of stairs in halls of assembly.
To avoid tripping or stumbling, care should be exercised, in the planning of a stairs, to secure an even grade. To this end, the nosing, or outer edge, of each step should be exactly in line with all the other nosings. In stairs composed of both flyers and winders, precaution in this regard is especially needed. In such stairs, the steps - flyers and winders alike - should be of one width on the line along which a person would naturally walk when having his hand upon the rail. This tread-line, consequently, would be parallel with the hand-rail, and is usually taken at a distance of from 18 to 20 inches from the centre of it. In the plan of the stairs this tread-line should be drawn and divided into equal parts, each part being the tread, or width of a flyer from the face of one riser to the face of the next.