Green is commentary:
SECTION 1020
CORRIDORS
1020.1 Construction. Corridors shall be fire-resistance rated
in accordance with Table 1020.1. The corridor walls required
to be fire-resistance rated shall comply with Section 708 for
fire partitions.
Exceptions:
1. A fire-resistance rating is not required for corridors
in an occupancy in Group E where each room that is
used for instruction has not less than one door opening
directly to the exterior and rooms for assembly
purposes have not less than one-half of the required
means of egress doors opening directly to the exterior.
Exterior doors specified in this exception are
required to be at ground level.
2. A fire-resistance rating is not required for corridors
contained within a dwelling unit or sleeping unit in
an occupancy in Groups I-1 and R.
3. A fire-resistance rating is not required for corridors
in open parking garages.
4. A fire-resistance rating is not required for corridors
in an occupancy in Group B that is a space requiring
only a single means of egress complying with Section
1006.2.
5. Corridors adjacent to the exterior walls of buildings
shall be permitted to have unprotected openings on
unrated exterior walls where unrated walls are permitted
by Table 602 and unprotected openings are
permitted by Table 705.8.
It is not the intent of this section to require corridors.
Once corridors are provided, so that occupants are
limited to a confined path of travel, then these provisions
apply.
The purpose of corridor enclosures is to provide
fire protection to occupants as they travel the confined
path, perhaps unaware of a fire buildup in an
adjacent floor area. The base protection is a fire partition
having a 1-hour fire-resistance rating (see Table
1020.1). The table allows a reduction or elimination of
the fire-resistance rating depending on the occupant
load and the presence of an NFPA 13 or 13R automatic
sprinkler system throughout the building.
Section 708 addresses the continuity of fire partitions
serving as corridor walls. In addition to allowing
the fire partitions to terminate at the underside of a
fire-resistance-rated floor/ceiling or roof/ceiling
assembly, the supporting construction need not have
the same fire-resistance rating in buildings of Type
IIB, IIIB and VB construction as specified in Section
708. If such walls were required to be supported by
fire-resistance-rated construction, the use of these
construction types would be severely restricted when
the corridors are required to have a fire-resistance
rating. Section 407.3 requires that corridor walls in
Group I-2 occupancies that are required to have a
fire-resistance rating must be continuous to the
underside of the floor or roof deck above or at a
smoke-limiting ceiling membrane. Continuity is
required because of the defend-in-place protection
strategy utilized in such buildings. Requirements for
corridor construction within Group I-3 occupancies
are found in Section 408.8. Dwelling unit separation
in Groups I-1, R-1, R-2 and R-3 is found in Sections
420.2 and 420.3. Ambulatory care facilities have special
requirements in Section 422.2 when some of the
patients can be incapable of self-preservation. For
additional requirements for an elevator lobby that is
adjacent to or part of a corridor, see the commentaries
to Sections 713.14 and 3006.
Exception 1 indicates a fire-resistance rating is not
required for corridors in Group E when any room
adjacent to the corridor that is used for instruction or
assembly purposes has a door directly to the outside.
The need for a fire-resistance-rated corridor is eliminated
because these rooms are provided with an
alternative egress path because of the requirement
for exterior exits. This option is typically utilized in
nonsprinklered buildings, such as day care facilities,
since a sprinkler system would also allow for unrated
corridors in Group E (see Table 1020.1). Grade
schools and high schools have security concerns that
sometimes make the outdoor exit for every classroom
not a preferred option.
In accordance with Exception 2, a fire-resistance
rating for a corridor contained within a single dwelling
unit (e.g., apartment, townhouse) or sleeping unit
(e.g., hotel guestroom, assistive living suite) is not
required for practical reasons. It is unreasonable to
expect fire doors and the associated hardware and
closing devices to be within dwellings and similar
occupancies.
Given the relatively smoke-free environment of
open parking structures, Exception 3 does not require
rated corridors in these types of facilities.
If an office suite is small enough that only one
means of egress is required from the suite, Exception
4 indicates that a rated corridor would not be required
in that area. The main corridor that connected these
suites to the exits would be evaluated in accordance
with Table 1020.1.
Exception 5 addresses when the exterior wall of a
building is also the wall of the corridor. The exterior
wall is not required to be rated by the corridor provisions
where there is a sufficient fire separation distance
for the exterior wall to be able to have
unprotected openings. This is similar to the exterior
wall for an enclosed interior exit stairway. The fire is
assumed to be inside the building, so that is where
the protection is required.
The required fire-resistance ratings of corridors serving
adjacent spaces are provided in Table 1020.1.
The fire-resistance rating is based on the group classification
(considering characteristics such as occupant
mobility, density and familiarity with the building
as well as the fire hazard associated with the classification),
the total occupant load served by the corridor
and the presence of an automatic sprinkler system.
Where the corridor serves a limited number of people
(second column in Table 1020.1), the fire-resistance
rating is eliminated because of the limited size
of the facility and the likelihood that the occupants
would become aware of a fire buildup in sufficient
time to exit the structure safely. The total occupant
load that the corridor serves is used to determine the
requirement for a rated corridor enclosure. The number
of occupants served is the total occupants that
will move into the corridor to egress. Corridors serving
a total occupant load equal to or less than that
indicated in the second column of Table 1020.1 are
not required to be enclosed with fire-resistance-rated
construction. For example, a corridor serving an
occupant load of 30 or less in an unsprinklered Group
B occupancy is not required to be enclosed with fireresistance-
rated construction. This example is illustrated
in Commentary Figure 1020.1.
The purpose of corridor enclosures is to provide
fire protection to occupants as they travel the confined
path, perhaps unaware of a fire buildup in an
adjacent floor area. The base protection is a fire partition
having a 1-hour fire-resistance rating. The table
allows a reduction or elimination of the fire-resistance
rating depending on the occupant load and the presence
of an NFPA 13 or 13R automatic sprinkler system
throughout the building.
A common mistake is assuming a building is sprinklered
throughout and utilizing the corridor rating
reductions, when in fact certain requirements in
NFPA 13 would not consider the building sprinklered
throughout. For example, a health club installs a
sprinkler system, but chooses to eliminate the sprinklers
over the swimming pool in accordance with the
exception in Section 507.4. Any corridors within the
building that serve greater than 30 occupants must
be rated because the building would not be considered
sprinklered throughout in accordance with NFPA
13 requirements.
Note that because of the hazardous nature of occupancies
in Groups H-1, H-2 and H-3, fire-resistancerated
corridors are required under all conditions.
Regardless of the presence of a fire sprinkler system,
a 1-hour-rated corridor enclosure is required in highhazard
occupancies with detonation, deflagration,
