N.Y. Multiple Dwelling Law § 237: Stair construction

§ 237. Stair construction. 1. Every stair in a tenement erected after

April twelfth, nineteen hundred one, shall be accessible on the entrance

story from a street or street court, or from an inner court which

connects directly with a street.

2. All such stairs shall have risers of eight inches or less and

treads at least ten inches in clear width and three feet in clear

length.

3. Winding stairs shall be unlawful except in a tenement provided with

a passenger elevator. When winding stairs or radial steps are installed

or used, the strings from which the risers radiate shall be curved on a

circle of at least one foot diameter, the treads shall be at least four

inches wide at the string, not including the nosing, and the angle

formed by the face of each riser and the string shall not diverge more

than forty degrees from a line normal to the string at the intersection

of such riser. It shall be unlawful to construct new winding stairs.

4. Stairs constructed after April eighteenth, nineteen hundred

twenty-nine, shall comply with the provisions of subdivisions two to six

inclusive of section fifty-two.