§ 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.