§ 134. Cellar entrance. There shall be a direct entrance to the cellar, or to the lowest story if there be no cellar, from the outside of every multiple dwelling, except that any stair leading to such cellar or lowest story may be located inside the dwelling provided it is enclosed in fireproof walls and fireproof doors and assemblies, with the doors self-closing, at both the level of such cellar or lowest story and that of the story above.