Exception: Any building protected throughout by an approved, supervised automatic sprinkler system installed in accordance with Section 17-3.5 having four stories or less with not more than four guest rooms or guest suites per floor shall be permitted to have a single exit under the following conditions:

(a) The stairway is completely enclosed or separated by barriers having a fire resistance rating of at least 1 hr with self-closing 1-hr fire protection-rated doors protecting all openings between the stairway enclosure and the building.

(b) The stairway does not serve more than one-half story below the level of exit discharge.

(c) All corridors serving as access to exits have at least a 1-hr fire resistance rating.

(d) There is not more than 35 ft (10.7 m) of travel distance from the entrance door of any guest room or guest suite to an exit.