Page 226 - 2018_IRC

WALL CONSTRUCTION

TABLE R602.10.3(4)
SEISMIC ADJUSTMENT FACTORS TO THE REQUIRED LENGTH OF WALL BRACING
ADJUSTMENT
FACTOR a, b
ITEM ADJUSTMENT [Multiply length APPLICABLE
NUMBER BASED ON STORY CONDITION from Table METHODS
R602.10.3(3) by this
factor]
Story height ≤ 10 feet 1.0
1 Any story
(Section 301.3) > 10 feet and ≤ 12 feet 1.2
Braced wall line ≤ 35 feet 1.0
2 spacing, townhouses Any story
in SDC C > 35 feet and ≤ 50 feet 1.43
Braced wall line > 25 feet and ≤ 30 feet 1.2
3 spacing, in Any story All methods
SDC D , D , D 2 c > 30 feet and ≤ 35 feet 1.4
1
0
> 8 psf and < 15 psf 1.0
4 Wall dead load Any story
< 8 psf 0.85
1-, 2- or 3-story building ≤15 psf 1.0
Roof/ceiling dead load
5 2- or 3-story building > 15 psf and ≤ 25 psf 1.1
for wall supporting
1-story building or top story > 15 psf and ≤ 25 psf 1.2
1.0

Walls with stone or
masonry veneer, 1.5
6 All methods
townhouses in
SDC C d, e

1.5

Walls with stone or
masonry veneer,
7 detached one- and Any story See Table R602.10.6.5 BV-WSP
two-family dwellings
in SDC D – D d, f
0 2
Walls with stone or
masonry veneer,
8 detached one- and First and second story of See Table R602.10.6.5 1.2 WSP, CS-WSP
two-story dwelling
two-family dwellings
in SDC D – D d, f
0 2
DWB, WSP,
Omitted from SFB, PBS, PCP,
Interior gypsum board
9 Any story inside face of braced 1.5 HPS,
finish (or equivalent)
wall panels CS-WSP, CS-G,
CS-SFB
10 Horizontal blocking Any story Horizontal blocking omitted 2.0 WSP, CS-WSP
For SI: 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
a. Linear interpolation shall be permitted.
b. The total length of bracing required for a given wall line is the product of all applicable adjustment factors.
c. The length-to-width ratio for the floor/roof diaphragm shall not exceed 3:1.
d. Applies to stone or masonry veneer exceeding the first story height.
e. The adjustment factor for stone or masonry veneer shall be applied to all exterior braced wall lines and all braced wall lines on the interior of the building,
backing or perpendicular to and laterally supporting veneered walls.
f. See Section R602.10.6.5 for requirements where stone or masonry veneer does not exceed the first-story height.

2018 INTERNATIONAL RESIDENTIAL CODE ® 201
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