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Buildings meeting all of the following conditions shall be permitted to be braced in accordance with this section as an alternative to the requirements of Section R602.10. The entire building shall be braced in accordance with this section; the use of other bracing provisions of Section R602.10, except as specified herein, shall not be permitted.
  1. There shall be not more than three stories above the top of a concrete or masonry foundation or basement wall. Permanent wood foundations shall not be permitted.
  2. Floors shall not cantilever more than 24 inches (607 mm) beyond the foundation or bearing wall below.
  3. Wall height shall not be greater than 10 feet (3048 mm).
  4. The building shall have a roof eave-to-ridge height of 15 feet (4572 mm) or less.
  5. Exterior walls shall have gypsum board with a minimum thickness of 1/2 inch (12.7 mm) installed on the interior side fastened in accordance with Table R702.3.5.
  6. The structure shall be located where the ultimate design wind speed is less than or equal to 130 mph (58 m/s), and the exposure category is B or C.
  7. The structure shall be located in Seismic Design Category A, B or C for detached one- and two-family dwellings or Seismic Design Category A or B for townhouses.
  8. Cripple walls shall not be permitted in three-story buildings.
R602.12.1 Circumscribed Rectangle
The bracing required for each building shall be determined by circumscribing a rectangle around the entire building on each floor as shown in Figure R602.12.1. The rectangle shall surround all enclosed offsets and projections such as sunrooms and attached garages. Open structures, such as carports and decks, shall be permitted to be excluded. The rectangle shall not have a side greater than 60 feet (18 288 mm), and the ratio between the long side and short side shall be not greater than 3:1.
FIGURE R602.12.1
RECTANGLE CIRCUMSCRIBING AN ENCLOSED BUILDING
R602.12.2 Sheathing Materials
The following sheathing materials installed on the exterior side of exterior walls shall be used to construct a bracing unit as defined in Section R602.12.3. Mixing materials is prohibited.
  1. Wood structural panels with a minimum thickness of 3/8 inch (9.5 mm) fastened in accordance with Table R602.3(3).
  2. Structural fiberboard sheathing with a minimum thickness of 1/2 inch (12.7 mm) fastened in accordance with Table R602.3(1).
R602.12.3 Bracing Unit
A bracing unit shall be a full-height sheathed segment of the exterior wall without openings or vertical or horizontal offsets and a minimum length as specified herein. Interior walls shall not contribute toward the amount of required bracing. Mixing of Items 1 and 2 is prohibited on the same story.
  1. Where all framed portions of all exterior walls are sheathed in accordance with Section R602.12.2, including wall areas between bracing units, above and below openings and on gable end walls, the minimum length of a bracing unit shall be 3 feet (914 mm).
  2. Where the exterior walls are braced with sheathing panels in accordance with Section R602.12.2 and areas between bracing units are covered with other materials, the minimum length of a bracing unit shall be 4 feet (1219 mm).
R602.12.3.1 Multiple Bracing Units
Segments of wall compliant with Section R602.12.3 and longer than the minimum bracing unit length shall be considered as multiple bracing units. The number of bracing units shall be determined by dividing the wall segment length by the minimum bracing unit length. Full-height sheathed segments of wall narrower than the minimum bracing unit length shall not contribute toward a bracing unit except as specified in Section R602.12.6.
R602.12.4 Number of Bracing Units
Each side of the circumscribed rectangle, as shown in Figure R602.12.1, shall have, at a minimum, the number of bracing units in accordance with Table R602.12.4 placed on the parallel exterior walls facing the side of the rectangle. Bracing units shall then be placed using the distribution requirements specified in Section R602.12.5.
TABLE R602.12.4
MINIMUM NUMBER OF BRACING UNITS ON EACH SIDE OF THE CIRCUMSCRIBED RECTANGLE
ULTIMATE DESIGN WIND SPEED (mph) STORY LEVEL EAVE-TO-RIDGE HEIGHT (feet) MINIMUM NUMBER OF BRACING UNITS ON EACH LONG SIDEa, b, d MINIMUM NUMBER OF BRACING UNITS ON EACH SHORT SIDEa, b, d
Length of short side (feet)c Length of long side (feet)c
10 20 30 40 50 60 10 20 30 40 50 60
115 10 1 2 2 2 3 3 1 2 2 2 3 3
2 3 3 4 5 6 2 3 3 4 5 6
2 3 4 6 7 8 2 3 4 6 7 8
15 1 2 3 3 4 4 1 2 3 3 4 4
2 3 4 5 6 7 2 3 4 5 6 7
2 4 5 6 7 9 2 4 5 6 7 9
130 10 1 2 2 3 3 4 1 2 2 3 3 4
2 3 4 5 6 7 2 3 4 5 6 7
2 4 5 7 8 10 2 4 5 7 8 10
15 2 3 3 4 4 6 2 3 3 4 4 6
3 4 6 7 8 10 3 4 6 7 8 10
3 6 7 10 11 13 3 6 7 10 11 13
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mile per hour = 0.447m/s.
  1. Interpolation shall not be permitted.
  2. Cripple walls or wood-framed basement walls in a walk-out condition shall be designated as the first story and the stories above shall be redesignated as the second and third stories, respectively, and shall be prohibited in a three-story structure.
  3. Actual lengths of the sides of the circumscribed rectangle shall be rounded to the next highest unit of 10 when using this table.
  4. For Exposure Category C, multiply bracing units by a factor of 1.20 for a one-story building, 1.30 for a two-story building and 1.40 for a three-story building.
R602.12.5 Distribution of Bracing Units
The placement of bracing units on exterior walls shall meet all of the following requirements as shown in Figure R602.12.5.
  1. A bracing unit shall begin not more than 12 feet (3658 mm) from any wall corner.
  2. The distance between adjacent edges of bracing units shall be not greater than 20 feet (6096 mm).
  3. Segments of wall greater than 8 feet (2438 mm) in length shall have not less than one bracing unit.


For SI: 1 foot = 304.8 mm.

FIGURE R602.12.5
BRACING UNIT DISTRIBUTION
R602.12.6 Narrow Panels
The bracing methods referenced in Section R602.10 and specified in Sections R602.12.6.1 through R602.12.6.3 shall be permitted where using simplified wall bracing.
R602.12.6.1 Method CS-G
Braced wall panels constructed as Method CS-G in accordance with Tables R602.10.4 and R602.10.5 shall be permitted for one-story garages where all framed portions of all exterior walls are sheathed with wood structural panels. Each CS-G panel shall be equivalent to 0.5 of a bracing unit. Segments of wall that include a Method CS-G panel shall meet the requirements of Section R602.10.4.2.
R602.12.6.2 Method CS-PF
Braced wall panels constructed as Method CS-PF in accordance with Section R602.10.6.4 shall be permitted where all framed portions of all exterior walls are sheathed with wood structural panels. Each CS-PF panel shall equal 0.75 bracing units. Segments of wall that include a Method CS-PF panel shall meet the requirements of Section R602.10.4.2.
R602.12.6.3 Methods ABW, PFH and PFG
Braced wall panels constructed as Method ABW, PFH and PFG shall be permitted where bracing units are constructed using wood structural panels applied either continuously or intermittently. Each ABW and PFH panel shall equal one bracing unit and each PFG panel shall be equal to 0.75 bracing unit.
R602.12.7 Lateral Support
For bracing units located along the eaves, the vertical distance from the outside edge of the top wall plate to the roof sheathing above shall not exceed 9.25 inches (235 mm) at the location of a bracing unit unless lateral support is provided in accordance with Section R602.10.8.2.
R602.12.8 Stem Walls
Masonry stem walls with a height and length of 48 inches (1219 mm) or less supporting a bracing unit or a Method CS-G, CS-PF or PFG braced wall panel shall be constructed in accordance with Figure R602.10.9. Concrete stem walls with a length of 48 inches (1219 mm) or less, greater than 12 inches (305 mm) tall and less than 6 inches (152 mm) thick shall be reinforced sized and located in accordance with Figure R602.10.9.

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R602.12 Wall Construction, Simplified Wall Bracing
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