§ 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.