a. In every old law tenement which is less than four stories in height:
(1) Every door opening into any entrance hall or stair, or into any public hall connected therewith, shall be self-closing; every glazed opening or glazed panel in such a door shall be glazed with wire glass, and every transom opening upon any public hall shall be glazed with wire glass firmly secured in a closed position; and
(2) Every interior sash, or opening other than a door, in the walls or partitions of any such hall, and every window in any such hall not opening to the outer air, shall be removed and the openings closed up and fire-retarded; and
(3) The ceiling of the cellar, or if there is no cellar, of the basement or other lowest story, shall be fire-retarded unless such ceiling already has been plastered or covered in a manner satisfactory to the department with plasterboard or gypsumboard at least one-half inch in thickness.
b. In every old law tenement which is four stories or more in height:
(1) On all stories above the third story, every apartment door opening into any stair or into any public hall connected therewith, unless such stair or public hall is protected by an approved sprinkler system shall have a fire resistance rating of at least one hour. Existing door frames in good condition may be retained. All such doors shall comply with this requirement, not later than November second, nineteen hundred seventy-three.
(2) For all stories below the fourth story, any application for an alteration permit for alterations to be made in an apartment below the fourth story shall include the provision that every door of such apartment opening into any entrance hall, stair or into any public hall connected therewith, unless such entrance hall, stair or public hall is protected by an approved sprinkler system, shall have a fire resistance rating of at least one hour. Existing door frames in good condition may be retained.
(3) Where apartment doors having a fire resistance rating of at least one hour are required, every transom opening upon any entrance hall, stair or public hall connected therewith shall be sealed and fireretarded. All other transoms opening upon any entrance hall, stair or public hall connected therewith shall be glazed with wire glass and permanently sealed in a closed position.
(4) All doors opening into any entrance hall, stair or into any public hall connected therewith shall be self-closing; every glazed opening or glazed panel in such a door shall be glazed with wire glass.