The intent of this document is to explain the requirements of, and exceptions to, Section 33.2..4 of the 2000 edition of the NFPA Life Safety Code. This section addresses interior stairs that are used as the facility's primary means of escape, and
more specifically, the need to enclose such stairways - with some exceptions.
The verbatim code language of Section 33.2.2.4 is:
33.2.2.4 Interior Stairs Used for Primary Means of Escape.
Interior stairs shall be enclosed with 1/2-hour fire barriers, with all openings equipped with smoke-actuated automatic-closing or self-closing doors having a fire protection rating comparable to that required for the enclosure.
Stairs shall comply with 7.2.2.5.3. The entire primary means of escape shall be arranged so that it is not necessary for occupants to pass through a portion of a lower story unless that route is separated from all spaces on that story by construction
having not less than a 1/2-hour fire resistance rating. In buildings of construction other than Type II(000), Type III(200), or Type V(000), the supporting construction shall be protected to afford the required fire resistance rating of the supported
wall.
This section is requiring that stairs which serve as the primary means of escape from a residential board and care occupancy, be enclosed with 1/2-hour fire rated barriers and that openings in such enclosures be protected with self-closing 1/2-hour
fire fire-rated doors. It is important to note the language which also stipulates that the means of escape must be arranged so that it is not necessary for occupants to pass through a portion of a lower story unless that route is separated from all
spaces by construction offering at least the same 1/2-hour fire resistance. (This is prohibiting the path of escape from upper or lower floors from exposing occupants to a fire or smoke on the first floor/grade level of the occupancy. The path to the
outside of the home must be protected/enclosed from the second floor down and out through the first floor or from the basement up and out through the first floor).
The Life Safety Code then offers four exceptions to this stairway enclosure requirement:
Exception No. 1: Stairs that connect a story at street level to only one other story shall be permitted to be open to the story that is not at street level.
Exception No. 2: Stair enclosures shall not be required in buildings of three or fewer stories that house prompt or slow evacuation capability facilities protected throughout by an approved automatic sprinkler system in accordance
with 33.2.3.5 that uses quick-response or residential sprinklers. This exception shall be permitted only if a primary means of escape from each sleeping area still exists that does not pass through a portion of a lower floor, unless that route is
separated from all spaces on that floor by construction having a 1/2-hour fire resistance rating.
Exception No. 3: Stair enclosures shall not be required in buildings of two or fewer stories that house prompt evacuation capability facilities with not more than eight residents and are protected by an approved automatic sprinkler
system in accordance with 33.2.3.5 that uses quick-response or residential sprinklers. Exception No. 2 to 33.2.2.3 shall not be used in conjunction with this exception. The exceptions to 33.2.3.4.3 shall not be used in conjunction with this
exception.
Exception No. 4: In buildings of three or fewer stories that house prompt or slow evacuation capability facilities protected by an approved automatic sprinkler system in accordance with 33.2.3.5, stairs shall be permitted to be open
at the topmost story only. The entire primary means of escape of which the stairs are a part shall be separated from all portions of lower stories.
Note that Exceptions No. 2, No. 3 and No. 4 require the presence of an automatic sprinkler system throughout the facility.
The essential misunderstanding that frequently occurs relative to Exception No. 1 is to mistakenly believe that this exception is allowing a completely unenclosed or unprotected stairway to exist between a second floor and the ground floor (i.e., the
"level of exit discharge) or between a basement and the ground floor. This misunderstanding is prompted by the language within the exception which includes the words "….permitted to be open…". However, the exception must be read more carefully and in its
entirety. The exception is allowing the stairwell to be open, but if you read on, only at the story that is not a street level. It is the intent of this exception to allow the absence of a fire rated door at the second floor level in a stairway that
connects the ground floor (level of exit discharge) to the second floor of a residential board and care occupancy. Similarly, the protecting door and/or enclosure could be absent at the basement level of a stairway that connects the basement to the
ground floor. However, the code is not allowing a completely open stairway (i.e., at both the ground floor and second floor; or at both the basement level and ground floor).
This understanding of Exception No. 1 is further supported by the Life Safety Code Handbook commentary pertaining to this section of the Life Safety Code. The following is the Life Safety Code Handbook commentary to this section (see pages
770-771):
"The intent of paragraph 33.2.2.4 is to require that an interior stair be enclosed if the stair serves as primary means of escape…….If the interior stair serves as the primary means of escape, it must be arranged so that occupants
are not required to pass through occupied or furnished portions of lower floors. Passage through unfurnished vestibule-like area on lower floors is permitted if such vestibules are separated from the occupied or furnished areas , or both, by walls and
doors. These vestibules provide safety equivalent to that provided by an enlarged stair enclosure…..
The intent of Exception #1 to 33.2.2.4 is to permit a stair that connect the first floor to the second floor to be open to the second floor but separated from the effects of fire on the first floor. The exception
also permits a stair that connects the basement level to the first floor to be open to the basement level but separated from the effects of fire on the fire floor……
The partially enclosed interior stair meeting the criteria of this exception is considered to be the equivalent of an enclosed interior stair. The separating walls and doors on the first floor serve the dual purposes of
enclosing the stair on that floor and providing a route that does not expose occupants to area of the first floor that are occupied or furnished, or both. Thus, the first floor stair "lobby" cannot be used as a lounge and cannot contain
furniture and furnishing."
Finally, examine Exception #1 and Exception #3. If it were mistakenly believed that Exception #1 was allowing a completely open stairway (i.e., open at both the second floor and at the ground floor), then why would any owner opt to use Exception #3
which requires the installation of a complete automatic sprinkler system in a two story occupancy? The reason that Exception #1 and #3 are different is because Exception #3 is allowing a completely open (unenclosed) stairway if the sprinkler protection
is installed while Exception #1 is only allowing the stairway to be open at other than the street level and still requiring the enclosure protection at the street level.
