§ 28. Stairs and entrance halls. In every such dwelling three stories
or more in height the wood wainscoting and other combustible materials
on the wall and ceiling surfaces in all halls shall be removed and
replaced with incombustible or other fire-resistive materials. In lieu
of such removal, a sprinkler system may be installed in such halls or
such wainscoting and the combustible surfaces may be treated or covered
in a manner satisfactory to the department with a surface fire-retardant
approved by the department. In such a dwelling, however, any entrance
door and every door opening into any entrance hall, stair hall, or other
public hall connected therewith, shall be self-closing. Every interior
sash, or opening other than a door, in the walls or partitions of such
halls and every window therein not opening to the outer air shall be
sealed with fire-resistive materials.