Pennsylvania Statutes Title 53 P.S. Municipal and Quasi-Municipal Corporations § 25009. Rise of stairways;  construction of halls and stairs

All stairways shall have a rise of not over eight inches to a step, and not less than nine inches tread, exclusive of the nosing.  All stairways and all hallways must not be less than three feet in width, in houses containing less than fifteen rooms;  not less than three feet six inches in width, in houses containing not less than fifteen rooms and not more than twenty-five rooms;  and not less than four feet in width, in houses containing twenty-five or more rooms.