NFPA Journal - Fall 2022 - 51

CODES, STANDARDS,
AND COMPLIANCE
NFPA 101
Life safety in new
and existing structures
Single-exit design in
multistory apartment
buildings
By Valerie Ziavras
M
ost multistory apartment
buildings in the
United States and
Canada require two
means of egress, which
usually means two exit stairs for occupants
to leave a building during a fire
or other emergency. But there's a push
underway across North America to
reduce that number to one exit stair,
driven in part by global design and
building trends. Multistory apartment
buildings with a single exit stair already
exist in countries around the world, and
the approach is beginning to catch on
here as well. Seattle's building code, for
instance, allows some buildings up to
six stories to be served by one exit stair.
Proponents of single-exit design point
to a number of reasons for eliminating
the second exit from multistory apartment
buildings. Having to design for
just a single exit, they argue, can result
in buildings with smaller, more flexible
footprints that fit on smaller parcels of
land, resulting in a more efficient use
of space, lower building costs, and, at
least in theory, more affordable housing
for buyers or renters. The popularity
of this approach in Europe and elsewhere
is often cited as proof that the
second stair is unnecessary and simply
takes up rentable space, which in turn
drives up associated costs. While there
is undoubtedly a host of critical issues
around affordable housing in much
of the world, it's doubtful whether
eliminating an exit stair is a suitable
approach to helping solve the problem.
A basic requirement of NFPA 101®
Life Safety Code®
,
, is that every portion
of a building includes two means of
egress, with each egress consisting of
exit access, exit, and exit discharge. This
fundamental component of NFPA 101
serves two main purposes. The first is
to provide an alternative route in the
event that a fire or similar emergency
blocks one of the means of egress. The
1946 Winecoff Hotel fire in Atlanta,
Georgia, illustrated the deadly ramifications
when a single exit stair becomes
blocked-in that fire, 119 people lost
their lives.
The second purpose of two means of
egress is that the design allows firefighters
to set up and attack the fire from
one of the exit stairs while occupants
continue to use the other means of
egress to exit the building. Firefighting
operations require the exit stair door
to be open, which allows smoke and
While there is
undoubtedly a host of
critical issues around
affordable housing in
much of the world, it's
doubtful whether
eliminating an exit
stair is a suitable
approach to helping
solve the problem.
heat to travel vertically. If other doors
to that stair are open, the effects from
the fire can compromise additional
floors and put occupants on those floors
at risk. Having an additional stair for
occupants to use minimizes their exposure
to smoke and heat. The 1980
MGM Grand hotel fire in Las Vegas,
which killed 85 people, demonstrated
how fatal the spread of smoke can be.
Although the fire was contained to the
first floor, the majority of the victims
were located on the upper floors. A
number of factors allowed the spread of
smoke in that fire, but exit stairs with
open doors were a contributing factor.
NFPA 101 contains exceptions to
the base requirement of two means of
egress. Most of the exceptions can be
found in the occupancy chapters and
are accompanied by a list of specific
criteria that also need to be met. One
example of this type of exemption, and
perhaps the most relevant, allows for a
single means of egress in an apartment
building that is four stories or less.
These buildings must meet a number
of additional criteria, including a limit
of no more than four dwelling units
per story, the installation of an automatic
sprinkler system throughout the
building, a minimum one-hour fire
resistance rating of exit access corridors,
and a minimum half-hour fire
resistance rated construction separating
dwelling units. In Seattle, the building
code allows a six-story building to
have a single means of egress-provided
a maximum of five of those stories are
served by that means of egress-but in
general many of the points highlighted
in the Life Safety Code are also required
by Seattle.
A major issue with proposals to
eliminate the second means of egress-
proposals that are based on practices
found in Europe and elsewhere-is
that they are being considered independent
of related aspects of building
safety. A building's fire protection and
life safety systems are referred to as
" systems " because they contain many
different components that must work
together. Picking and choosing different
approaches without an understanding
or appreciation for how they can
affect the whole will likely not result
in a building that is truly safe. While
a single means of egress is the norm
in many European countries, so is the
use of noncombustible building materials,
along with more compartmentation
inside the structure. In the United
States, by contrast, traditional woodframe
construction is still commonly
used-just one example of why applying
a single aspect of the European
approach to fire protection and life
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