§ 233. Bulkheads and scuttles. 1. Every tenement, except as in this section otherwise provided, shall have in the roof a fireproof bulkhead with a fireproof door and after January first, nineteen hundred fifty-seven, the door shall be self-closing. Bulkheads existing on April eighteenth, nineteen hundred twenty-nine, shall be lawful and may be replaced or repaired with material conforming to the material of which such bulkhead consisted on such date.

2. A bulkhead in the roof of an old-law tenement which is more than a basement and four other stories in height or which is a basement and four other stories in height and occupied by three or more families on any story, may be of wood covered with metal on the outside and fire-retarded on the inside. Such a bulkhead shall be equipped with a fire-retarded door and assembly with the door self-closing.

3. In any old-law tenement which is four stories or less in height or which is a basement and four other stories in height and occupied by not more than two families on any story, no bulkhead shall be required provided such tenement is equipped with a scuttle located in the ceiling of a public hall on the top story and with access thereto direct, uninterrupted and easily accessible to all tenants. All such scuttles shall be at least twenty-one inches in width and twenty-eight inches in length. They shall be constructed so as to be readily opened, covered on the outside with metal and provided with stairs or stationary iron ladders leading thereto.

4. Every required stair in every tenement erected after April eighteenth, nineteen hundred twelve, which is more than a basement and three other stories in height shall extend to and through a bulkhead in the roof. Such bulkhead shall have a fireproof door and assembly with the door self-closing and may be constructed of wood covered with metal on the outside and fire-retarded on the inside.

5. Stairs leading to required bulkheads shall be fireproof and constructed as specified in sections two hundred thirty-four to two hundred thirty-eight inclusive, except that any such stairs existing on April eighteenth, nineteen hundred twenty-nine, shall be permitted without alteration, and that any such stairs constructed after such date in any old-law tenement may have such width and angle of ascent, and risers and treads of such dimensions, as approved by the department. All stairs to required bulkheads shall be provided with a guide or hand rail.

6. Bulkhead doors and scuttles shall not be self-locking, and shall be fastened on the inside with movable bolts, hooks, or a lock which does not require a key to open it from the inside of the dwelling. All key locks are unlawful and where existing shall be removed.