Cal. Civ. Code § 55

  § 55. Egress. 1. In every transient dwelling to which this article is
applicable there shall be from each story at least two independent means
of egress accessible to each room, apartment or suite, except as
otherwise provided in section sixty-three with respect to two story
transient dwellings.
  2. The first means of egress shall be an enclosed stair extending
directly to a street, or to a yard, court or passageway affording
continuous, safe and unobstructed access to a street, or by an enclosed
stair leading to the entrance story, which story shall have direct
access to a street. That area of the dwelling immediately above the
street level and commonly known as the main floor, where the occupants
are registered and the usual business of the dwelling is conducted,
shall be considered a part of the entrance story; and a required stair
terminating at such main floor or its mezzanine shall be deemed to
terminate at the entrance story. An elevator or an unenclosed escalator
shall not be acceptable as a required means of egress.
  3. The second means of egress shall be by an additional enclosed
stair, conforming to the provisions of subdivision two of this section,
a fire-stair or an outside fire-escape. In a non-fireproof dwelling when
it is necessary to pass through a stair enclosure which may or may not
be a required means of egress to reach a required means of egress, such
stair enclosure and that part of the public hall or corridor leading
thereto from a room, apartment or suite, shall be fire-retarded as
provided in section fifty-two or protected by a sprinkler system; in a
fireproof dwelling only that part of the hall or corridor leading to
such stair enclosure need be so protected.
  4. Where it is impractical in such existing transient dwellings to
provide a second means of egress, the department may order, in lieu of
the second means of egress, additional alteration to the first means of
egress and to shafts, stairs and other vertical openings as the
department may deem necessary to safeguard the occupants of the
dwelling, may require the public halls providing access to the first
means of egress to be equipped on each story with an automatic sprinkler
system, and, in non-fireproof dwellings, may also require automatic
sprinkler heads in the stair which serves as the only means of egress.
  5. Nothing in this section shall be deemed to require the enclosure of
a stair which is ornamental provided such stair does not connect more
than two stories.
  6. A stair, fire-stair or fire-escape supplementary to the egress
requirements of subdivisions two, three and four of this section need
not lead to the entrance story or to a street, or to a yard or a court
which leads to a street, provided the means of egress therefrom is
approved by the department.
  7. A fire-detecting system shall not be acceptable for any of the
requirements of this section.
  8. In lieu of enclosing stairways as required by subdivisions two and
three of this section, an automatic sprinkler system may be provided on
such stairs.
  9. All fire-escapes erected on or after July first, nineteen hundred
fifty-three, in compliance with this section, shall be arranged,
constructed and maintained in accordance with the provisions of section
one hundred thirty-three. Such system shall be installed, arranged and
maintained in a manner satisfactory to the department and in accordance
with rules adopted by the commission. It shall be unlawful to remove any
fire-escape without permission from the department.