Page 219 - 2018_Complete_14_Collection (1)_Neat

FIRE AND SMOKE PROTECTION FEATURES

722.4.1.1.2 Solid grouted clay units. The equiva- TABLE 722.4.1(6)
lent thickness of solid grouted clay masonry units REINFORCED CLAY MASONRY COLUMNS
shall be taken as the actual thickness of the units. FIRE-RESISTANCE RATING
722.4.1.1.3 Units with filled cores. The equivalent COLUMN SIZE (hours)
thickness of the hollow clay masonry units is the 1 2 3 4
actual thickness of the unit where completely filled Minimum column dimension (inches) 8 10 12 14
with loose-fill materials of: sand, pea gravel,
crushed stone, or slag that meet ASTM C33 require- For SI: 1 inch = 25.4 mm.
ments; pumice, scoria, expanded shale, expanded 722.4.1.3 Multiwythe walls with airspace. Where a
clay, expanded slate, expanded slag, expanded fly continuous airspace separates multiple wythes of the
ash, or cinders in compliance with ASTM C331; or wall or partition, the total fire-resistance rating shall be
perlite or vermiculite meeting the requirements of
ASTM C549 and ASTM C516, respectively. determined by the formula:
722.4.1.2 Plaster finishes. Where plaster is applied to R = (R 1 0.59 + R 2 0.59 + ...+R 0.59 + as) 1.7 (Equation 7-10)
the wall, the total fire-resistance rating shall be deter- n
mined by the formula: where:
R = (R 0.59 + pl) 1.7 (Equation 7-9) R= The fire-resistance rating of the assembly (hours).
n
where: R , R and R =The fire-resistance rating of the
R= The fire-resistance rating of the assembly (hours). 1 2 n individual wythes (hours).
R =The fire-resistance rating of the individual wall
n as = Coefficient for continuous airspace.
(hours).
pl = Coefficient for thickness of plaster. Values for R n 0.59 for use in Equation 7-10 are given
Values for R n 0.59 for use in Equation 7-9 are given in in Table 722.4.1(3). The coefficient for each continu-
1
1
Table 722.4.1(3). Coefficients for thickness of plaster ous airspace of / inch to 3 / inches (12.7 to 89 mm)
2
2
shall be selected from Table 722.4.1(4) based on the separating two individual wythes shall be 0.3.
actual thickness of plaster applied to the wall or parti- 722.4.1.4 Nonsymmetrical assemblies. For a wall
tion and whether one or two sides of the wall are plas- without finish on one side or having different types or
tered. thicknesses of finish on each side, the calculation pro-
TABLE 722.4.1(3) cedures of this section shall be performed twice, assum-
VALUES OF R 0.59 ing either side to be the fire-exposed side of the wall.
n
R n 0.59 R (hours) The fire resistance of the wall shall not exceed the
1 1 . 0 lower of the two values determined.
2 1 . 5 0 Exception: For exterior walls with a fire separation
3 1 . 9 1 distance greater than 5 feet (1524 mm), the fire shall
be assumed to occur on the interior side only.
4 2 . 2 7
722.4.2 Multiwythe walls. The fire-resistance rating for
TABLE 722.4.1(4) walls or partitions consisting of two or more dissimilar
COEFFICIENTS FOR PLASTER, pl a wythes shall be permitted to be determined by the for-
THICKNESS OF PLASTER (inch) ONE SIDE TWO SIDES mula:
1 / 2 0.3 0.6 R = (R 0.59 + R 0.59 + ...+R 0.59 1.7 (Equation 7-11)
)
5 / 8 0.37 0.75 where: 1 2 n
3 / 0.45 0.90
4
R =The fire-resistance rating of the assembly (hours).
For SI: 1 inch = 25.4 mm.
a. Values listed in the table are for 1:3 sanded gypsum plaster. R , R and R =The fire-resistance rating of the
n
2
1
individual wythes (hours).
TABLE 722.4.1(5)
REINFORCED MASONRY LINTELS Values for R n 0.59 for use in Equation 7-11 are given in
NOMINAL MINIMUM LONGITUDINAL REINFORCEMENT Table 722.4.1(3).
LINTEL WIDTH COVER FOR FIRE RESISTANCE (inches)
(inches) 1 hour 2 hours 3 hours 4 hours 722.4.2.1 Multiwythe walls of different material. For
walls that consist of two or more wythes of different
6 1 1 / 2 2 N P N P materials (concrete or concrete masonry units) in com-
8 1 1 / 1 / 1 / 3 bination with clay masonry units, the fire-resistance
3
1
2 2 4 rating of the different materials shall be permitted to be
1
1
1
3
10 or more 1 / 2 1 / 2 1 / 2 1 / 4 determined from Table 722.2.1.1 for concrete; Table
For SI: 1 inch = 25.4 mm. 722.3.2 for concrete masonry units or Table 722.4.1(1)
NP = Not Permitted. or 722.4.1(2) for clay and tile masonry units.
192 2018 INTERNATIONAL BUILDING CODE ®
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