Page 244 - 2018_IRC

WALL CONSTRUCTION

6. The structure shall be located where the ultimate design ings or vertical or horizontal offsets and a minimum length
wind speed is less than or equal to 130 mph (58 m/s), and as specified herein. Interior walls shall not contribute
the exposure category is B or C. toward the amount of required bracing. Mixing of Items 1
7. The structure shall be located in Seismic Design Cate- and 2 is prohibited on the same story.
gory A, B or C for detached one- and two-family dwell- 1. Where all framed portions of all exterior walls are
ings or Seismic Design Category A or B for sheathed in accordance with Section R602.12.2,
townhouses. including wall areas between bracing units, above
8. Cripple walls shall not be permitted in three-story and below openings and on gable end walls, the
buildings. minimum length of a bracing unit shall be 3 feet
(914 mm).
R602.12.1 Circumscribed rectangle. The bracing
required for each building shall be determined by circum- 2. Where the exterior walls are braced with sheathing
scribing a rectangle around the entire building on each panels in accordance with Section R602.12.2 and
floor as shown in Figure R602.12.1. The rectangle shall areas between bracing units are covered with other
surround all enclosed offsets and projections such as sun- materials, the minimum length of a bracing unit
rooms and attached garages. Open structures, such as car- shall be 4 feet (1219 mm).
ports and decks, shall be permitted to be excluded. The R602.12.3.1 Multiple bracing units. Segments of
rectangle shall not have a side greater than 60 feet (18 288 wall compliant with Section R602.12.3 and longer than
mm), and the ratio between the long side and short side the minimum bracing unit length shall be considered as
shall be not greater than 3:1. multiple bracing units. The number of bracing units
R602.12.2 Sheathing materials. The following sheathing shall be determined by dividing the wall segment
materials installed on the exterior side of exterior walls length by the minimum bracing unit length. Full-height
shall be used to construct a bracing unit as defined in Sec- sheathed segments of wall narrower than the minimum
tion R602.12.3. Mixing materials is prohibited. bracing unit length shall not contribute toward a brac-
ing unit except as specified in Section R602.12.6.
1. Wood structural panels with a minimum thickness
of / inch (9.5 mm) fastened in accordance with R602.12.4 Number of bracing units. Each side of the
3
8
Table R602.3(3). circumscribed rectangle, as shown in Figure R602.12.1,
shall have, at a minimum, the number of bracing units in
2. Structural fiberboard sheathing with a minimum accordance with Table R602.12.4 placed on the parallel
1
thickness of / inch (12.7 mm) fastened in accor- exterior walls facing the side of the rectangle. Bracing
2
dance with Table R602.3(1). units shall then be placed using the distribution require-
R602.12.3 Bracing unit. A bracing unit shall be a full- ments specified in Section R602.12.5.
height sheathed segment of the exterior wall without open-

LONG SIDE LONG SIDE

TYPICAL
WALL
CORNER

SHORT SIDE TYPICAL SEGMENTS OF SHORT SIDE TYPICAL SEGMENTS OF
WALL BETWEEN CORNERS
WALL BETWEEN CORNERS

CIRCUMSCRIBING RECTANGLE CIRCUMSCRIBING RECTANGLE

FIRST FLOOR PLAN SECOND FLOOR PLAN

FIGURE R602.12.1
RECTANGLE CIRCUMSCRIBING AN ENCLOSED BUILDING

2018 INTERNATIONAL RESIDENTIAL CODE ® 219
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