§ 108. Windows and skylights for public halls and stairs. 1. Where a
window or windows are required to light a public hall or part thereof,
at least one of such windows shall be not less than two feet six inches
wide and five feet high. Every required window in such a hall shall open
upon a street, yard or court. On the top story of such a dwelling a
ventilating skylight of the same dimensions shall be accepted in lieu of
a window for that story.

2. There shall be in the roof, directly over each required stair and
fire-stair a ventilating skylight provided with louvres or ventilators
having a minimum open area of forty square inches. The roof of every
such skylight shall be glazed with plain glass and equipped with
suitable metal screens above and below. The glazed area of every such
skylight shall be at least twenty square feet, except that in such a
dwelling or section thereof two stories or less in height the glazed
area of such a skylight need be only nine square feet. In lieu of a
skylight, a window of the same area as prescribed in subdivision one may
be provided. If such a window is used in lieu of a skylight, fixed
louvres having a minimum opening of forty square inches shall also be
installed in or directly adjacent to such window.

3. When any stair, fire-stair or fire-tower in such a dwelling
terminates at the level of a setback of an outer wall and such setback
consists of a terrace at least four feet in width, measured between the
inside of the parapet wall and the wall of the dwelling and at least ten
feet in length, measured parallel to the wall of the dwelling, there may
be provided in lieu of such skylight a fireproof door and assembly with
the door self-closing giving access from such stair or fire-stair to
such terrace. Such door shall have a panel at least five square feet in
area glazed with wire glass and shall be equipped with louvres having a
minimum open area of forty square inches.