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R602.10.3 Required Length of Bracing
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The required length of bracing along each braced wall line shall be determined as follows:
- All buildings in Seismic Design Categories A and B shall use Table R602.10.3(1) and the applicable adjustment factors in Table R602.10.3(2).
- Detached buildings in Seismic Design Category C shall use Table R602.10.3(1) and the applicable adjustment factors in Table R602.10.3(2).
- Townhouses in Seismic Design Category C shall use the greater value determined from Table R602.10.3(1) or R602.10.3(3) and the applicable adjustment factors in Table R602.10.3(2) or R602.10.3(4), respectively.
- All buildings in Seismic Design Categories D0, D1 and D2 shall use the greater value determined from Table R602.10.3(1) or R602.10.3(3) and the applicable adjustment factors in Table R602.10.3(2) or R602.10.3(4), respectively.
Only braced wall panels parallel to the braced wall line shall contribute toward the required length of bracing of that braced wall line. Braced wall panels along an angled wall meeting the minimum length requirements of Tables R602.10.5 and R602.10.5.2 shall be permitted to contribute its projected length toward the minimum required length of bracing for the braced wall line as shown in Figure R602.10.1.4. Any braced wall panel on an angled wall at the end of a braced wall line shall contribute its projected length for only one of the braced wall lines at the projected corner.
Exception: The length of wall bracing for dwellings in Seismic Design Categories D0, D1 and D2 with stone or masonry veneer installed in accordance with Section R703.8 and exceeding the first-story height shall be in accordance with Section R602.10.6.5.
BRACING REQUIREMENTS BASED ON WIND SPEED
| • EXPOSURE CATEGORY B
• 30-FOOT MEAN ROOF HEIGHT
• 10-FOOT WALL HEIGHT
|
MINIMUM TOTAL LENGTH (FEET) OF BRACED WALL PANELS
REQUIRED ALONG EACH BRACED WALL LINEa
|
|||||
| Ultimate
Design Wind
Speed
(mph)
|
Story Location | Braced Wall Line
Spacingc
(feet)
|
Method LIBb | Method GB | Methods
DWB, WSP, SFB,
PBS, PCP, HPS,
BV-WSP, ABW, PFH,
PFC, CS-SFB
|
Methods
CS-WSP, CS-G,
CS-PF
|
| ≤ 110 |  |
10 | 3.5 | 3.5 | 2.0 | 1.5 |
| 20 | 6.0 | 6.0 | 3.5 | 3.0 | ||
| 30 | 8.5 | 8.5 | 5.0 | 4.5 | ||
| 40 | 11.5 | 11.5 | 6.5 | 5.5 | ||
| 50 | 14.0 | 14.0 | 8.0 | 7.0 | ||
| 60 | 16.5 | 16.5 | 9.5 | 8.0 | ||
 |
10 | 6.5 | 6.5 | 3.5 | 3.0 | |
| 20 | 11.5 | 11.5 | 6.5 | 5.5 | ||
| 30 | 16.5 | 16.5 | 9.5 | 8.0 | ||
| 40 | 21.5 | 21.5 | 12.5 | 10.5 | ||
| 50 | 26.5 | 26.5 | 15.5 | 13.0 | ||
| 60 | 31.5 | 31.5 | 18.0 | 15.5 | ||
 |
10 | NP | 9.5 | 5.5 | 4.5 | |
| 20 | NP | 17.0 | 10.0 | 8.5 | ||
| 30 | NP | 24.5 | 14.0 | 12.0 | ||
| 40 | NP | 32.0 | 18.5 | 15.5 | ||
| 50 | NP | 39.5 | 22.5 | 19.0 | ||
| 60 | NP | 46.5 | 26.5 | 23.0 | ||
| ≤ 115 |  |
10 | 3.5 | 3.5 | 2.0 | 2.0 |
| 20 | 6.5 | 6.5 | 3.5 | 3.5 | ||
| 30 | 9.5 | 9.5 | 5.5 | 4.5 | ||
| 40 | 12.5 | 12.5 | 7.0 | 6.0 | ||
| 50 | 15.0 | 15.0 | 9.0 | 7.5 | ||
| 60 | 18.0 | 18.0 | 10.5 | 9.0 | ||
 |
10 | 7.0 | 7.0 | 4.0 | 3.5 | |
| 20 | 12.5 | 12.5 | 7.5 | 6.5 | ||
| 30 | 18.0 | 18.0 | 10.5 | 9.0 | ||
| 40 | 23.5 | 23.5 | 13.5 | 11.5 | ||
| 50 | 29.0 | 29.0 | 16.5 | 14.0 | ||
| 60 | 34.5 | 34.5 | 20.0 | 17.0 | ||
 |
10 | NP | 10.0 | 6.0 | 5.0 | |
| 20 | NP | 18.5 | 11.0 | 9.0 | ||
| 30 | NP | 27.0 | 15.5 | 13.0 | ||
| 40 | NP | 35.0 | 20.0 | 17.0 | ||
| 50 | NP | 43.0 | 24.5 | 21.0 | ||
| 60 | NP | 51.0 | 29.0 | 25.0 | ||
| ≤ 120 |  |
10 | 4.0 | 4.0 | 2.5 | 2.0 |
| 20 | 7.0 | 7.0 | 4.0 | 3.5 | ||
| 30 | 10.5 | 10.5 | 6.0 | 5.0 | ||
| 40 | 13.5 | 13.5 | 8.0 | 6.5 | ||
| 50 | 16.5 | 16.5 | 9.5 | 8.0 | ||
| 60 | 19.5 | 19.5 | 11.5 | 9.5 | ||
 |
10 | 7.5 | 7.5 | 4.5 | 3.5 | |
| 20 | 14.0 | 14.0 | 8.0 | 7.0 | ||
| 30 | 20.0 | 20.0 | 11.5 | 9.5 | ||
| 40 | 25.5 | 25.5 | 15.0 | 12.5 | ||
| 50 | 31.5 | 31.5 | 18.0 | 15.5 | ||
| 60 | 37.5 | 37.5 | 21.5 | 18.5 | ||
 |
10 | NP | 11.0 | 6.5 | 5.5 | |
| 20 | NP | 20.5 | 11.5 | 10.0 | ||
| 30 | NP | 29.0 | 17.0 | 14.5 | ||
| 40 | NP | 38.0 | 22.0 | 18.5 | ||
| 50 | NP | 47.0 | 27.0 | 23.0 | ||
| 60 | NP | 55.5 | 32.0 | 27.0 | ||
| ≤ 130 |  |
10 | 4.5 | 4.5 | 2.5 | 2.5 |
| 20 | 8.5 | 8.5 | 5.0 | 4.0 | ||
| 30 | 12.0 | 12.0 | 7.0 | 6.0 | ||
| 40 | 15.5 | 15.5 | 9.0 | 7.5 | ||
| 50 | 19.5 | 19.5 | 11.0 | 9.5 | ||
| 60 | 23.0 | 23.0 | 13.0 | 11.0 | ||
 |
10 | 8.5 | 8.5 | 5.0 | 4.5 | |
| 20 | 16.0 | 16.0 | 9.5 | 8.0 | ||
| 30 | 23.0 | 23.0 | 13.5 | 11.5 | ||
| 40 | 30.0 | 30.0 | 17.5 | 15.0 | ||
| 50 | 37.0 | 37.0 | 21.5 | 18.0 | ||
| 60 | 44.0 | 44.0 | 25.0 | 21.5 | ||
 |
10 | NP | 13.0 | 7.5 | 6.5 | |
| 20 | NP | 24.0 | 13.5 | 11.5 | ||
| 30 | NP | 34.5 | 19.5 | 17.0 | ||
| 40 | NP | 44.5 | 25.5 | 22.0 | ||
| 50 | NP | 55.0 | 31.5 | 26.5 | ||
| 60 | NP | 65.0 | 37.5 | 31.5 | ||
| < 140 |  |
10 | 5.5 | 5.5 | 3.0 | 2.5 |
| 20 | 10.0 | 10.0 | 5.5 | 5.0 | ||
| 30 | 14.0 | 14.0 | 8.0 | 7.0 | ||
| 40 | 18.0 | 18.0 | 10.5 | 9.0 | ||
| 50 | 22.5 | 22.5 | 13.0 | 11.0 | ||
| 60 | 26.5 | 26.5 | 15.0 | 13.0 | ||
 |
10 | 10.0 | 10.0 | 6.0 | 5.0 | |
| 20 | 18.5 | 18.5 | 11.0 | 9.0 | ||
| 30 | 27.0 | 27.0 | 15.5 | 13.0 | ||
| 40 | 35.0 | 35.0 | 20.0 | 17.0 | ||
| 50 | 43.0 | 43.0 | 24.5 | 21.0 | ||
| 60 | 51.0 | 51.0 | 29.0 | 25.0 | ||
 |
10 | NP | 15.0 | 8.5 | 7.5 | |
| 20 | NP | 27.5 | 16.0 | 13.5 | ||
| 30 | NP | 39.5 | 23.0 | 19.5 | ||
| 40 | NP | 51.5 | 29.5 | 25.0 | ||
| 50 | NP | 63.5 | 36.5 | 31.0 | ||
| 60 | NP | 75.5 | 43.0 | 36.5 | ||
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mile per hour = 0.447 m/s.
NP = Not Permitted.
- Linear interpolation shall be permitted.
- Method LIB shall have gypsum board fastened to not less than one side with nails or screws in accordance with Table R602.3(1) for exterior sheathing or Table R702.3.5 for interior gypsum board. Spacing of fasteners at panel edges shall not exceed 8 inches.
- Where three or more parallel braced wall lines are present and the distances between adjacent braced wall lines are different, the average dimension shall be permitted to be used for braced wall line spacing.
WIND ADJUSTMENT FACTORS TO THE REQUIRED LENGTH OF WALL BRACING
| ITEM NUMBER | ADJUSTMENT BASED ON | STORY/SUPPORTING | CONDITION | ADJUSTMENT FACTORa, b [multiply length from Table R602.10.3(1) by this factor] | APPLICABLE METHODS |
| 1 | Exposure categoryd | One-story
structure
|
B | 1.00 | All methods |
| C | 1.20 | ||||
| D | 1.50 | ||||
| Two-story
structure
|
B | 1.00 | |||
| C | 1.30 | ||||
| D | 1.60 | ||||
| Three-story
structure
|
B | 1.00 | |||
| C | 1.40 | ||||
| D | 1.70 | ||||
| 2 | Roof eave-to-ridge
height
|
Roof only | ≤ 5 feet | 0.70 | |
| 10 feet | 1.00 | ||||
| 15 feet | 1.30 | ||||
| 20 feet | 1.60 | ||||
| Roof + 1 floor | ≤ 5 feet | 0.85 | |||
| 10 feet | 1.00 | ||||
| 15 feet | 1.15 | ||||
| 20 feet | 1.30 | ||||
| Roof + 2 floors | ≤ 5 feet | 0.90 | |||
| 10 feet | 1.00 | ||||
| 15 feet | 1.10 | ||||
| 20 feet | Not permitted | ||||
| 3 | Story height | Any story | 8 feet | 0.90 | |
| 9 feet | 0.95 | ||||
| 10 feet | 1.00 | ||||
| 11 feet | 1.05 | ||||
| 12 feet | 1.10 | ||||
| 4 | Number of braced
wall lines (per plan
direction)c
|
Any story | 2 | 1.00 | |
| 3 | 1.30 | ||||
| 4 | 1.45 | ||||
| ≥ 5 | 1.60 | ||||
| 5 | Additional 800-pound
hold-down device
|
Top story only | Fastened to the end
studs of each braced
wall panel and to the
foundation or framing
below
|
0.80 | DWB, WSP, SFB,
PBS, PCP, HPS
|
| 6 | Interior gypsum board
finish (or equivalent)
|
Any story | Omitted from inside face | 1.40 | DWB, WSP, SFB,
PBS, PCP, HPS, CS-
WSP, CS-G, CS-SFB
|
| 7 | Gypsum board
fastening
|
Any story | 4 inches o.c. at panel
edges, including top
and bottom plates, and
all horizontal joints
blocked
|
0.7 | GB |
| 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.
- Linear interpolation shall be permitted.
- The total adjustment factor is the product of all applicable adjustment factors.
- 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.
- 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.
BRACING REQUIREMENTS BASED ON SEISMIC DESIGN CATEGORY
| • SOIL CLASS Db
• WALL HEIGHT = 10 FEET
• 10 PSF FLOOR DEAD LOAD
• 15 PSF ROOF/CEILING DEAD LOAD
• BRACED WALL LINE SPACING
≤ 25 FEET |
MINIMUM TOTAL LENGTH (FEET) OF BRACED WALL PANELS
REQUIRED ALONG EACH BRACED WALL LINEa, f
|
||||||
| Seismic Design
Category
|
Story Location | Braced Wall Line
Length
(feet)c
|
Method LIBd | Method GB | Methods
DWB, SFB, PBS,
PCP, HPS,
CS-SFBe
|
Methods WSP, ABW, PFH and PFGe | Methods
CS-WSP,
CS-G, CS-PF
|
| C
(townhouses only)
|
 |
10 | 2.5 | 2.5 | 2.5 | 1.6 | 1.4 |
| 20 | 5.0 | 5.0 | 5.0 | 3.2 | 2.7 | ||
| 30 | 7.5 | 7.5 | 7.5 | 4.8 | 4.1 | ||
| 40 | 10.0 | 10.0 | 10.0 | 6.4 | 5.4 | ||
| 50 | 12.5 | 12.5 | 12.5 | 8.0 | 6.8 | ||
 |
10 | NP | 4.5 | 4.5 | 3.0 | 2.6 | |
| 20 | NP | 9.0 | 9.0 | 6.0 | 5.1 | ||
| 30 | NP | 13.5 | 13.5 | 9.0 | 7.7 | ||
| 40 | NP | 18.0 | 18.0 | 12.0 | 10.2 | ||
| 50 | NP | 22.5 | 22.5 | 15.0 | 12.8 | ||
 |
10 | NP | 6.0 | 6.0 | 4.5 | 3.8 | |
| 20 | NP | 12.0 | 12.0 | 9.0 | 7.7 | ||
| 30 | NP | 18.0 | 18.0 | 13.5 | 11.5 | ||
| 40 | NP | 24.0 | 24.0 | 18.0 | 15.3 | ||
| 50 | NP | 30.0 | 30.0 | 22.5 | 19.1 | ||
| D0 |  |
10 | NP | 2.8 | 2.8 | 1.8 | 1.6 |
| 20 | NP | 5.5 | 5.5 | 3.6 | 3.1 | ||
| 30 | NP | 8.3 | 8.3 | 5.4 | 4.6 | ||
| 40 | NP | 11.0 | 11.0 | 7.2 | 6.1 | ||
| 50 | NP | 13.8 | 13.8 | 9.0 | 7.7 | ||
 |
10 | NP | 5.3 | 5.3 | 3.8 | 3.2 | |
| 20 | NP | 10.5 | 10.5 | 7.5 | 6.4 | ||
| 30 | NP | 15.8 | 15.8 | 11.3 | 9.6 | ||
| 40 | NP | 21.0 | 21.0 | 15.0 | 12.8 | ||
| 50 | NP | 26.3 | 26.3 | 18.8 | 16.0 | ||
 |
10 | NP | 7.3 | 7.3 | 5.3 | 4.5 | |
| 20 | NP | 14.5 | 14.5 | 10.5 | 9.0 | ||
| 30 | NP | 21.8 | 21.8 | 15.8 | 13.4 | ||
| 40 | NP | 29.0 | 29.0 | 21.0 | 17.9 | ||
| 50 | NP | 36.3 | 36.3 | 26.3 | 22.3 | ||
| D1 |  |
10 | NP | 3.0 | 3.0 | 2.0 | 1.7 |
| 20 | NP | 6.0 | 6.0 | 4.0 | 3.4 | ||
| 30 | NP | 9.0 | 9.0 | 6.0 | 5.1 | ||
| 40 | NP | 12.0 | 12.0 | 8.0 | 6.8 | ||
| 50 | NP | 15.0 | 15.0 | 10.0 | 8.5 | ||
 |
10 | NP | 6.0 | 6.0 | 4.5 | 3.8 | |
| 20 | NP | 12.0 | 12.0 | 9.0 | 7.7 | ||
| 30 | NP | 18.0 | 18.0 | 13.5 | 11.5 | ||
| 40 | NP | 24.0 | 24.0 | 18.0 | 15.3 | ||
| 50 | NP | 30.0 | 30.0 | 22.5 | 19.1 | ||
 |
10 | NP | 8.5 | 8.5 | 6.0 | 5.1 | |
| 20 | NP | 17.0 | 17.0 | 12.0 | 10.2 | ||
| 30 | NP | 25.5 | 25.5 | 18.0 | 15.3 | ||
| 40 | NP | 34.0 | 34.0 | 24.0 | 20.4 | ||
| 50 | NP | 42.5 | 42.5 | 30.0 | 25.5 | ||
| D2 |  |
10 | NP | 4.0 | 4.0 | 2.5 | 2.1 |
| 20 | NP | 8.0 | 8.0 | 5.0 | 4.3 | ||
| 30 | NP | 12.0 | 12.0 | 7.5 | 6.4 | ||
| 40 | NP | 16.0 | 16.0 | 10.0 | 8.5 | ||
| 50 | NP | 20.0 | 20.0 | 12.5 | 10.6 | ||
 |
10 | NP | 7.5 | 7.5 | 5.5 | 4.7 | |
| 20 | NP | 15.0 | 15.0 | 11.0 | 9.4 | ||
| 30 | NP | 22.5 | 22.5 | 16.5 | 14.0 | ||
| 40 | NP | 30.0 | 30.0 | 22.0 | 18.7 | ||
| 50 | NP | 37.5 | 37.5 | 27.5 | 23.4 | ||
 |
10 | NP | NP | NP | NP | NP | |
| 20 | NP | NP | NP | NP | NP | ||
| 30 | NP | NP | NP | NP | NP | ||
| 40 | NP | NP | NP | NP | NP | ||
| 50 | NP | NP | NP | NP | NP | ||
| Cripple wall below | 10 | NP | NP | NP | 7.5 | 6.4 | |
| 20 | NP | NP | NP | 15.0 | 12.8 | ||
| 30 | NP | NP | NP | 22.5 | 19.1 | ||
| 40 | NP | NP | NP | 30.0 | 25.5 | ||
| 50 | NP | NP | NP | 37.5 | 31.9 | ||
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
NP = Not Permitted.
- Linear interpolation shall be permitted.
- Wall bracing lengths are based on a soil site class "D." Interpolation of bracing length between the Sds values associated with the seismic design categories shall be permitted when a site-specific Sds value is determined in accordance with Section 1613.2 of the International Building Code.
- Where the braced wall line length is greater than 50 feet, braced wall lines shall be permitted to be divided into shorter segments having lengths of 50 feet or less, and the amount of bracing within each segment shall be in accordance with this table.
- Method LIB shall have gypsum board fastened to not less than one side with nails or screws in accordance with Table R602.3(1) for exterior sheathing or Table R702.3.5 for interior gypsum board. Spacing of fasteners at panel edges shall not exceed 8 inches.
- Methods PFG and CS-SFB do not apply in Seismic Design Categories D0, D1 and D2.
- Where more than one bracing method is used, mixing methods shall be in accordance with Section R602.10.4.1.
SEISMIC ADJUSTMENT FACTORS TO THE REQUIRED LENGTH OF WALL BRACING
| ITEM
NUMBER
|
ADJUSTMENT
BASED ON
|
STORY | CONDITION | ADJUSTMENT
FACTORa, b
[Multiply length
from
Table R602.10.3(3) by this
factor]
|
APPLICABLE
METHODS
|
| 1 | Story height
(Section 301.3)
|
Any story | ≤ 10 feet | 1.0 | All methods |
| > 10 feet and ≤ 12 feet | 1.2 | ||||
| 2 | Braced wall line
spacing, townhouses
in SDC C
|
Any story | ≤ 35 feet | 1.0 | |
| > 35 feet and ≤ 50 feet | 1.43 | ||||
| 3 | Braced wall line
spacing, in
SDC D0, D1, D2c
|
Any story | > 25 feet and ≤ 30 feet | 1.2 | |
| > 30 feet and ≤ 35 feet | 1.4 | ||||
| 4 | Wall dead load | Any story | > 8 psf and < 15 psf | 1.0 | |
| < 8psf | 0.85 | ||||
| 5 | Roof/ceiling dead load
for wall supporting
|
1-, 2- or 3-story building | ≤15 psf | 1.0 | |
| 2- or 3-story building | > 15 psf and ≤ 25 psf | 1.1 | |||
| 1-story building or top story | > 15 psf and ≤ 25 psf | 1.2 | |||
| 6 | Walls with stone or
masonry veneer,
townhouses in
SDCCd, e
|
 |
1.0 | All methods | |
 |
1.5 | ||||
 |
1.5 | ||||
| 7 | Walls with stone or
masonry veneer,
detached one- and
two-family dwellings
in SDC D0 — D2d, f
|
Any story | See Table R602.10.6.5 | BV-WSP | |
| 8 | Walls with stone or
masonry veneer,
detached one- and
two-family dwellings
in SDC D0 — D2d, f
|
First and second story of two-story dwelling | See Table R602.10.6.5 | 1.2 | WSP, CS-WSP |
| 9 |
Interior gypsum board
finish (or equivalent) |
Any story | Omitted from
inside face of braced
wall panels |
1.5 |
DWB, WSP,
SFB, PBS, PCP,
HPS,
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.
- Linear interpolation shall be permitted.
- The total length of bracing required for a given wall line is the product of all applicable adjustment factors.
- The length-to-width ratio for the floor/roof diaphragm shall not exceed 3:1.
- Applies to stone or masonry veneer exceeding the first story height.
- 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.
- See Section R602.10.6.5 for requirements where stone or masonry veneer does not exceed the first-story height.