SECTION 704 EXTERIOR
WALLS 704.1
General. Exterior walls shall comply with this section.
704.2 Projections. Cornices,
eave overhangs, exterior balconies and similar projections extending
beyond the floor area shall conform to the requirements of this
section and Section Exterior egress balconies and exterior exit
stairways shall also comply
with Sections 1014.5 and 1023.1,
respectively. Projections shall not extend beyond the distance
determined by the following two methods, whichever results in
the lesser projection:
1. A
point one-third the distance to the lot line from an assumed
vertical plane located where protected openings are required
in accordance with Section 704.8. 2. More
than 12 inches (305 mm) into areas where openings
are prohibited.
704.2.1 Type I and II construction.
Projections from walls of Type I or II construction shall
be of noncombustible materials or combustible materials
as allowed by Sections 1406.3 and
1406.4.
704.2.2 Type III, IV or
V construction. Projections from walls of Type III,
IV or V construction shall be of any approved material.
704.2.3 Combustible
projections. Combustible projections located where openings
are not permitted or where protection of openings is required
shall be of at least 1-hour fire-resistance rated construction,
Type IV construction, fire-retardant-treated
wood or as required by Section 1406.3.
Exception: Type V construction
shall be allowed for R-3 occupancies.
704.3 Buildings on the same
lot. For the purposes of determining the required wall
and opening protection and roof-covering requirements, buildings
on the same lot shall be assumed to have an imaginary line
between them. Where a
new building is to be erected on the same lot as an existing
building, the location of the assumed imaginary line with
relation to the existing building shall be such that the exterior
wall and opening protection of the existing building meet
the criteria as set forth in Sections 704.5 and 704.8.
Exception:
Two or more buildings on the same lot shall either be regulated
as separate buildings or shall be considered as portions of
one building if the aggregate area of such buildings is within
the limits specified in Chapter 5 for a single building. Where
the buildings contain different occupancy groups or are of
different types of construction, the area shall be that allowed
for the most restrictive occupancy or construction.
704.4 Materials. Exterior
walls shall be of materials permitted by the building type
of construction.
704.5 Fire-resistance ratings.
Exterior walls shall be fire-resistance rated in accordance
with Tables 601 and 602.
The fire-resistance rating of exterior walls with a fire separation
distance of greater than 5 feet (1524 mm) shall be rated for
exposure to fire from the inside. The fire-resistance rating
of exterior walls with a fire separation distance of 5 feet
(1524 mm) or less shall be rated for exposure to fire from
both sides.
704.6 Structural stability.
The wall shall extend to the height required by Section
704.11 and shall have sufficient structural stability such
that it will remain in place for the duration of time indicated
by the required fire-resistance rating.
704.7 Unexposed surface temperature.
Where protected openings are not limited by Section 704.8,
the limitation on the rise of temperature on the unexposed
surface of exterior walls as required by ASTM E 119 shall
not apply. Where protected openings are limited by Section
704.8, the limitation on the rise of temperature on the unexposed
surface of exterior walls as required by ASTM E 119 shall
not apply provided that a correction is made for radiation
from the unexposed exterior wall surface in accordance with
the following formula:
(Equation 7-1)
where:
Ae = Equivalent area of
protected openings.
A = Actual area of protected
openings.
Af = Area of exterior wall
surface in the story under consideration exclusive of openings,
on which the temperature limitations of ASTME119 for walls
are exceeded.
Feo = An equivalent opening factor
derived from Figure 704.7 based
on the average temperature of the unexposed wall surface and
the fire-resistance rating of the wall.
704.8 Allowable area of openings.
The maximum area of unprotected or protected openings permitted
in an exterior wall in any story shall not exceed the values
set forth in Table 704.8. Where
both unprotected and protected openings are located in the
exterior wall in any story, the total area of the openings
shall comply with the following formula:
704.8.1 Automatic
sprinkler system. In buildings equipped throughout with
an automatic sprinkler system in accordance with Section
903.3.1.1, the maximum allowable area of unprotected openings
in occupancies other than Groups H -1, H - 2 and H - 3 shall
be the same as the tabulated limitations for protected openings.704.8.2
First story. In occupancies other than Group H, unlimited
unprotected openings are permitted in the exterior walls of
the first story above grade facing a street that have a fire
separation distance of greater than 15 feet (4572 mm) or facing
an unoccupied space. The unoccupied space shall be on the
same lot or dedicated for public use, shall not be less than
30 feet (9144 mm) in width and shall have access from a street
by a posted fire lane in accordance with the International
Fire Code.
704.9 Vertical separation of
openings. Openings in exterior walls in adjacent stories
shall be separated vertically to protect against fire spread
on the exterior of the buildings where the openings are within
5 feet (1524 mm) of each other horizontally and the opening
in the lower story is not a protected opening with a fire protection
rating of not less than 3/4 hour. Such
openings shall be separated vertically at least 3 feet (914
mm) by spandrel girders, exterior walls or other similar assemblies
that have a fire-resistance rating of at least 1 hour or by
flame barriers that extend horizontally at least 30 inches (762
mm) beyond the exterior wall. Flame barriers shall also have
a fire-resistance rating of at least 1 hour. The unexposed surface
temperature limitations specified in ASTM E 119 shall not apply
to the flame barriers or vertical separation unless otherwise
required by the provisions of this code. Exceptions:
1.This section shall
not apply to buildings that are three stories or less in height.
2. This section shall
not apply to buildings equipped throughout with an automatic
sprinkler system in accordance with Section
903.3.1.1 or 903.3.1.2. 3. Open
parking garages.
704.10 Vertical exposure.
For buildings on the same lot, opening protectives having a
fire-protection rating of not less than 3/4
hour shall be provided in every opening that is less than 15
feet (4572 mm) vertically above the roof of an adjoining building
or adjacent structure that is within a horizontal fire separation
distance of 15 feet (4572 mm) of the wall in which the opening
is located. Exception:
Opening protectives are not required where the roof construction
has a fire-resistance rating of not less than 1 hour for a minimum
distance of 10 feet (3048 mm) from the adjoining building, and
the entire length and span of the supporting elements for the
fire-resistance-rated roof assembly has a fire-resistance rating
of not less than 1 hour.
704.11 Parapets. Parapets shall be provided on exterior
walls of buildings. Exceptions:
A parapet need not be provided on an exterior wall where
any of the following conditions exist:
1.The wall is not
required to be fire-resistance rated in accordance with
Table 602 because of fire separation
distance. 2. The
building has an area of not more than 1,000 square feet
(93 m2) on any floor. 3. Walls
that terminate at roofs of not less than 2-hour fire-resistance-rated
construction or where the roof, including the deck and supporting
construction, is constructed entirely of noncombustible
materials. 4. One-hour
fire-resistance-rated exterior walls that terminate at the
underside of the roof sheathing, deck or slab, provided:
4.1. Where the
roof/ceiling framing elements are parallel to the walls,
such framing and elements supporting such framing shall
not be of less than 1-hour fire-resistance-rated construction
for a width of 4 feet (1220 mm) for Groups Rand U and
10 feet (3048 mm) for other occupancies, measured from
the interior side of the wall. 4.2.
Where roof/ceiling framing elements are not parallel to
the wall, the entire span of such framing and elements
supporting such framing shall not be of less than 1-hour
fire-resistance-rated construction. 4.3.
Openings in the roof shall not be located within 5 feet
(1524 mm) of the 1-hour fire-resistance-rated exterior
wall for Groups Rand U and 10 feet (3048 mm) for other
occupancies, measured from the interior side of the wall.
4.4. The entire building
shall be provided with not less than a Class B roof covering.
5. In Groups R-2 and R-3
where the entire building is provided with a Class C roof
covering, the exterior wall shall be permitted to terminate
at the underside of the roof sheathing or deck in Type III,
IV and V construction, provided:
5.1. The roof sheathing
or deck is constructed of approved noncombustible materials
or of fire-retardant-treated wood for a distance of 4
feet (1220 mm); or 5.2.
The roof is protected with 0.625-inch (16 mm) Type X gypsum
board directly beneath the underside of the roof sheathing
or deck, supported by a minimum of nominal 2-inch (51
mm) ledgers attached to the sides of the roof framing
members for a minimum distance of 4 feet (1220 mm).
6. Where the wall is permitted
to have at least 25 percent of the exterior wall areas containing
unprotected openings based on fire separation distance as
determined in accordance with Section 704.8.
704.11.1 Parapet construction.
Parapets shall have the same fire-resistance rating as that
required for the supporting wall, and on any side adjacent to
a roof surface, shall have noncombustible faces for the uppermost
18 inches (457 mm), including counter flashing and coping materials.
The height of the parapet shall not be less than 30 inches (762
mm) above the point where the roof surface and the wall intersect.
Where the roof slopes toward a parapet at a slope greater than
two units vertical in 12 units horizontal (16.7-percent slope),
the parapet shall extend to the same height as any portion of
the roof within a fire separation distance where protection
of wall openings is required, but in no case shall the height
be less than 30 inches (762 mm).
704.12
Opening protection. Windows in exterior walls required to
have protected openings in accordance with other sections of
this code or determined to be protected in accordance with
Section 704.3 or 704.8 shall comply with
Section 715.5. Other openings required to be protected with
fire door or shutter assemblies in accordance with other sections
of this code or determined to be protected in accordance with
Section 704.3 or 704.8 shall comply with Section
715.4. Exception:
Opening protectives are not required where the building is protected
throughout by an automatic sprinkler system and the exterior
openings are protected by an approved water curtain using automatic
sprinklers approved for that use. The sprinklers and the water
curtain shall be installed in accordance with Section
903.3.1.1 and shall have an automatic water supply and fire
department connection.
704.12.1 Unprotected
openings. Where protected openings are not required by
Section 704, windows and doors shall be constructed of any
approved materials. Glazing shall conform to the requirements
of Chapters 24 and 26.
704.13 Joints. Joints made
in or between exterior walls required by this section to have
a fire-resistance rating shall comply with Section
713. Exception:
Joints in exterior walls that are permitted to have unprotected
openings.
704.13.1 Voids.
The void created at the intersection of a floor/ceiling assembly
and an exterior curtain wall assembly shall be protected in
accordance with Section 713.4.
704.14 Ducts and air transfer
openings. Penetrations by air ducts and air transfer openings
in fire-resistance-rated exterior walls required to have protected
openings shall comply with Section 716.
Exception: Foundation vents
installed in accordance with this code are permitted. |