Page 223 - 2018_IRC

WALL CONSTRUCTION

TABLE R602.10.3(2)
WIND ADJUSTMENT FACTORS TO THE REQUIRED LENGTH OF WALL BRACING
ADJUSTMENT
FACTOR a, b
ITEM
NUMBER ADJUSTMENT BASED ON STORY/SUPPORTING CONDITION [multiply length from APPLICABLE METHODS
Table R602.10.3(1) by
this factor]
B 1 . 0 0
One-story C 1 . 2 0
structure
D 1 . 5 0
B 1 . 0 0
Two-story
1 Exposure category d C 1 . 3 0
structure
D 1 . 6 0
B 1 . 0 0
Three-story C 1 . 4 0
structure
D 1 . 7 0
≤ 5 feet 0.70
10 feet 1.00
Roof only
15 feet 1.30
20 feet 1.60
≤ 5 feet 0.85
Roof eave-to-ridge 10 feet 1.00
2 Roof + 1 floor All methods
height 15 feet 1.15
20 feet 1.30
≤ 5 feet 0.90
10 feet 1.00
Roof + 2 floors
15 feet 1.10
20 feet Not permitted
8 feet 0.90
9 feet 0.95
Story height
3 Any story 10 feet 1.00
(Section R301.3)
11 feet 1.05
12 feet 1.10
2 1 . 0 0
Number of braced wall 3 1 . 3 0
4 lines (per plan Any story
direction) c 4 1 . 4 5
≥ 5 1 . 6 0
Fastened to the end studs of
Additional 800-pound each braced wall panel and to DWB, WSP, SFB,
5 Top story only 0.80
hold-down device the foundation or framing PBS, PCP, HPS
below
DWB, WSP, SFB,
Interior gypsum board Omitted from inside face of
6 Any story 1.40 PBS, PCP, HPS, CS-
finish (or equivalent) braced wall panels
WSP, CS-G, CS-SFB
4 inches o.c. at panel edges,
Gypsum board including top and bottom
7 Any story 0.7 GB
fastening plates, and all horizontal
joints blocked
8 Horizontal blocking Any story Horizontal block is omitted 2.0 WSP, CS-WSP
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound = 4.48 N.
a. Linear interpolation shall be permitted.
b. The total adjustment factor is the product of all applicable adjustment factors.
c. The adjustment factor is permitted to be 1.0 when determining bracing amounts for intermediate braced wall lines provided the bracing amounts on adjacent
braced wall lines are based on a spacing and number that neglects the intermediate braced wall line.
d. The same adjustment factor shall be applied to all braced wall lines on all floors of the structure, based on the worst-case exposure category.

198 2018 INTERNATIONAL RESIDENTIAL CODE ®
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