Page 217 - 2018_Complete_14_Collection (1)_Neat

FIRE AND SMOKE PROTECTION FEATURES

plus the equivalent thickness of finishes, T , deter- masonry wall contributes to its fire-resistance rating,
ef
mined in accordance with Section 722.3.2: the masonry alone shall provide not less than one-half
the total required fire-resistance rating.
T = T + T (Equation 7-6)
ea e ef
722.3.2.5 Attachment of finishes. Installation of fin-
722.3.1.2 Ungrouted or partially grouted construc- ishes shall be as follows:
tion. T shall be the value obtained for the concrete
e
masonry unit determined in accordance with ASTM 1. Gypsum wallboard and gypsum lath applied to
C140. concrete masonry or concrete walls shall be
secured to wood or steel furring members spaced
722.3.1.3 Solid grouted construction. The equivalent not more than 16 inches (406 mm) on center
thickness, T , of solid grouted concrete masonry units is (o.c.).
e
the actual thickness of the unit.
2. Gypsum wallboard shall be installed with the
722.3.1.4 Airspaces and cells filled with loose-fill long dimension parallel to the furring members
material. The equivalent thickness of completely filled and shall have all joints finished.
hollow concrete masonry is the actual thickness of the
unit where loose-fill materials are: sand, pea gravel, 3. Other aspects of the installation of finishes shall
crushed stone, or slag that meet ASTM C33 require- comply with the applicable provisions of Chap-
ments; pumice, scoria, expanded shale, expanded clay, ters 7 and 25.
expanded slate, expanded slag, expanded fly ash, or 722.3.3 Multiwythe masonry walls. The fire-resistance
cinders that comply with ASTM C331; or perlite or rating of wall assemblies constructed of multiple wythes
vermiculite meeting the requirements of ASTM C549 of masonry materials shall be permitted to be based on the
and ASTM C516, respectively. fire-resistance rating period of each wythe and the contin-
722.3.2 Concrete masonry walls. The fire-resistance rat- uous airspace between each wythe in accordance with the
ing of walls and partitions constructed of concrete following formula:
masonry units shall be determined from Table 722.3.2. 0.59 0.59 0.59 + A + A + ... + A ) 1.7
The rating shall be based on the equivalent thickness of R = (R 1 + R 2 + ... + R n 1 2 n
A
the masonry and type of aggregate used. (Equation 7-7)
722.3.2.1 Finish on nonfire-exposed side. Where plas- where:
ter or gypsum wallboard is applied to the side of the R = Fire-resistance rating of the assembly (hours).
A
wall not exposed to fire, the contribution of the finish to = Fire-resistance rating of wythes for 1, 2,
the total fire-resistance rating shall be determined as R , R , ..., R n n (hours), respectively.
2
1
follows: The thickness of gypsum wallboard or plaster
shall be corrected by multiplying the actual thickness of A , A , ...., A = 0.30, factor for each continuous airspace
n
1
2
the finish by applicable factor determined from Table for 1, 2, ...n, respectively, having a depth
1
722.2.1.4(1). This corrected thickness of finish shall be of / inch (12.7 mm) or more between
2
added to the equivalent thickness of masonry and the wythes.
fire-resistance rating of the masonry and finish deter- 722.3.4 Concrete masonry lintels. Fire-resistance rat-
mined from Table 722.3.2. ings for concrete masonry lintels shall be determined
722.3.2.2 Finish on fire-exposed side. Where plaster based on the nominal thickness of the lintel and the mini-
or gypsum wallboard is applied to the fire-exposed side mum thickness of concrete masonry or concrete, or any
of the wall, the contribution of the finish to the total combination thereof, covering the main reinforcing bars,
fire-resistance rating shall be determined as follows: as determined in accordance with Table 722.3.4, or by
The time assigned to the finish as established by Table approved alternate methods.
722.2.1.4(2) shall be added to the fire-resistance rating TABLE 722.3.4
determined in Section 722.3.2 for the masonry alone, or MINIMUM COVER OF LONGITUDINAL
in Section 722.3.2.1 for the masonry and finish on the REINFORCEMENT IN FIRE-RESISTANCE-RATED
nonfire-exposed side. REINFORCED CONCRETE MASONRY LINTELS (inches)
722.3.2.3 Nonsymmetrical assemblies. For a wall NOMINAL WIDTH FIRE-RESISTANCE RATING (hours)
without finish on one side or having different types or OF LINTEL (inches) 1 2 3 4
thicknesses of finish on each side, the calculation pro- 6 1 1 / 2 2 — —
cedures of this section shall be performed twice, assum- 8 1 1 / 1 / 1 / 3
3
1
ing either side of the wall to be the fire-exposed side. 2 2 4
3
1
1
1
The fire-resistance rating of the wall shall not exceed 10 or greater 1 / 2 1 / 2 1 / 2 1 / 4
the lower of the two values calculated. For SI: 1 inch = 25.4 mm.
Exception: For exterior walls with a fire separation 722.3.5 Concrete masonry columns. The fire-resistance
distance greater than 5 feet (1524 mm), the fire shall rating of concrete masonry columns shall be determined
be assumed to occur on the interior side only. based on the least plan dimension of the column in accor-
722.3.2.4 Minimum concrete masonry fire-resis- dance with Table 722.3.5 or by approved alternate meth-
tance rating. Where the finish applied to a concrete ods.
190 2018 INTERNATIONAL BUILDING CODE ®
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