§ 234. Stairs and public halls. 1. In every tenement erected after
April eighteenth, nineteen hundred twelve, all stairs shall extend from
the entrance story to the roof, except as otherwise provided in section
two hundred thirty-three, and the stairs and public halls shall each be
at least three feet in clear width. Every apartment in such a tenement
shall be directly accessible at each story to such stairs and public
halls, and every story of such apartment shall be so accessible to such
a stair and public hall or to a tower fire-escape or stairway, as
provided in this section and sections two hundred thirty-five to two
hundred thirty-nine inclusive.

2. In every tenement erected after April twelfth, nineteen hundred
one, except as provided in paragraph b of subdivision two of section two
hundred thirty-eight, all stairs and public halls shall be completely
separated from all other stairs and from every elevator by brick walls
or partitions of terra cotta blocks at least four inches thick, or
hollow cement blocks at least four inches thick which have successfully
withstood a three-hour standard fire test and been approved by the
department and have fireproof doors and assemblies with the doors
self-closing at all openings. From any portion of a public hall in such
a tenement there may be a recess which shall not be deemed a public hall
if the walls, floor and ceilings enclosing it are fire-retarded and such
recess is at all times adequately lighted by electric lights of at least
fifteen watts or equivalent illumination. Such a recess shall not be
more than twenty feet long and shall not be used as a means of egress
from more than three apartments.