§ 190. Cellar stairs. 1. Except as provided in paragraph g of subdivision three of section one hundred seventy-one, and except as otherwise provided in subdivision two hereof, every stair leading from a cellar to the floor above shall be constructed of incombustible materials, shall have closed risers, shall be completely enclosed with partitions of incombustible materials and shall be equipped at the bottom with a fireproof door and assembly with the door self-closing.

2. Every existing stair leading from a cellar to the floor above in a converted dwelling accepted or approved by the department on or before July first, nineteen hundred sixty shall be deemed in compliance with this section.