If any portion of the first story exterior walls of any building structure is more than 150 feet from the edge of the roadway of an approved street, an approved fire lane shall be provided so that such portion is within 150 feet of the edge of the fire lane.
EXCEPTION: An entrance to any dwelling unit or guest room shall not be more than 150 feet in distance of horizontal travel from the edge of roadway of an improved street or approved fire lane.