The diagram does show only one but I think the illustration is for clarity showing that you can use either one.
This allows designers to have windows at the end of a wall and still meet the bracing requirements.
The 2006 IRC specified that windbracing must be within 12 1/2 feet of the corner and if you had the WB at 12 1/2 feet then the opposite end had to be AT the corner.
The 2009 IRC allows you to bring a window towards the corner as long as windbracing and a hold down device is within 12 1/2 feet of the corner. If you want to split that difference so that you have a window on each end of a braced wall then you can use a combination of 12 1/2 feet from the ends. On one end you could put a window within 3 feet of the corner and then on the opposite end you could go up to 9 1/2 feet from the corner.
This is where the hold down device comes into play. If you cannot get 24" of sheathing on the corner then you can use the alternate in lieu of the 24" piece. The intent of the code is to create a resistance to uplift on the corner perpendicular to the adjoining corner.
You are creating resistance to uplift perpendicular to walls not windbracing. Even though the method does count towards windbracing on that wall. Clear as mud??? :banghd
This is from the commentary (I know)
For bracing Method CS-WSP, a corner, as shown in Figures R602.10.4.4(1) and R602.4.4(2), or some other method of anchoring the wall is required at each end of the braced wall line. A 24-inch (610 mm) corner return is required in accordance with Figure R602.10.4.4(1).
The purpose of the corner attachment for the continuous sheathing bracing methods is to connect the intersecting walls together to create a stronger, box-like structure that will perform better during high wind or seismic events. The corner detail requires a minimum
of a single row of 16d nails at 12 inches (305 mm) on center. A double row of 16d nails at 24 inches (610 mm) on center, framing member orientation permitting, is considered equivalent. It is important to note that the intent of Figure R602.10.4.4(1) is to provide the specified amount of nailing between the two studs, each on adjacent walls, to which the adjacent wall sheathing is attached.
An 800-pound (3560 N) hold-down device—required to be attached between the stud at the edge of the braced wall panel closest to the corner and the foundation below—can be used in lieu of the return corner [see Figure R602.10.4.4(3)]. If two continuously sheathed
braced wall lines meet at a corner, and the first braced panel is spaced away from the corner on one of the wall lines, then both braced wall lines lose the structural effect of the corner return; therefore, both braced wall lines must be anchored with an 800-pound (3560
N) hold-down device at the edge adjacent to the corner.
The previous paragraph provided the code exceptions when corner return requirements cannot be met. Permitted bracing away from a corner in continuously sheathed wall lines is an example of when such an exception is necessary.For Method CS-WSP wall panel and corner construction, the 2009 code allows the first full-height braced wall segment of the continuously sheathed braced wall line to
be spaced away from the end of the braced wall line, in accordance with the exception to Section R602.10.4.4. [see Figure R602.10.4.4(4) and R602.10.4.4(5)]. Note that if two continuously sheathed wall lines meet at a corner, and along one of the two wall lines, the first bracing panel is displaced from this common corner, then both braced wall lines are denied the structural effect of the corner return. In this case, both wall lines must be anchored with an 800-pound (3560 N) hold-down device.
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