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IRC Wall Bracing R602.10 Question

jar546

jar546

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In the 2021 IRC, Section R602.10 details the requirements for wall bracing. Within this section, there's a provision for wall bracing based on a house's seismic design category and braced wall line spacing. Given a home in Seismic Design Category D2 with a braced wall line spacing of more than 25 feet but not exceeding 35 feet, what is the minimum length of bracing required when using Method Wood Structural Panel Sheathing for the braced wall panels?
 
Couple items...

Take note that the maximum BWL spacing, per Table R602.10.1.3, is actually 25'. An exception will allow BWL spacing of up to 35' in a SFD of one- or two-story construction "...to allow for a single room not to exceed 900 square feet. Spacing of all other braced wall lines shall not exceed 25 feet."

From R602.10.3, "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."

And that's as far as anyone can answer your question, as insufficient information is provided to completely determine values from Table R602.10.3(1) and R602.10.3(3), nor apply the applicable adjustment factors in Table R602.10.3(2) or R602.10.3(4).
 
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One other note to add, in case I misunderstood the question. In the OP, I believe the question is regarding the total length of bracing along a BWL.

However, if the question is simply the minimum width of an individual WSP panel, then the answer is simply 48-inches as per Table R602.10.5.

I'll note further, that partial credit for panels less than 48-inches is unavailable for a WSP panel in SDC D2; see R602.10.5.2.
 
Rick18071 said:
I'm glad they took all those sections about wall bracing out of the code in PA. Seems complicated.
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It actually simplified it by breaking it down and allowing contractors to do work that otherwise would have required an engineer. It took 6 pages that were difficult to grasp (therefore no one enforces it in PA) and sectioned it off into 30 plus pages giving the contractors and designers lots of options prescriptively. Unfortunately, the ignorance of the PHBA only saw it go from 6 pages to thirty, and rather than understand it for what it was and how much better it was, they lobbied to have it removed, thereby allowing ignorance to run rampant as plans examiners in that state approve things they are not supposed to because they don't know any better. Ignorance is bliss.
 
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I'd say that it is complicated, but once you figure it out, it is quite straightforward and results in a very practical and defensible design requirement.
 
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jar546 said:
In the 2021 IRC, Section R602.10 details the requirements for wall bracing. Within this section, there's a provision for wall bracing based on a house's seismic design category and braced wall line spacing. Given a home in Seismic Design Category D2 with a braced wall line spacing of more than 25 feet but not exceeding 35 feet, what is the minimum length of bracing required when using Method Wood Structural Panel Sheathing for the braced wall panels?
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CS-WSP I think is "always" 24" absolute minimum unless you are using a portal...I don't think that changes with wind or seismic...Table 602.10.5

Minimum gets bigger depending on the adjacent opening....One thing I have struggled with is "how adjacent" is adjacent?
 
steveray said:
CS-WSP I think is "always" 24" absolute minimum unless you are using a portal...I don't think that changes with wind or seismic...Table 602.10.5

Minimum gets bigger depending on the adjacent opening....One thing I have struggled with is "how adjacent" is adjacent?
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Check the OP - - specified WSP not CS-WSP.

Minimum panel width is specified in Table R602.10.5, and for CS-WSP you are correct that the minimum panel width is 24", but that would only be allowed for an 8' wall height and an adjacent clear opening ≤ 64". Minimum panel width increases with taller walls and taller openings.

Not sure why you have struggled with adjacent. For method CS-WSP, the whole wall is sheathed. Every section of wall wherein there is not a window/door/opening contributes to the overall length of the braced walls, unless the panel width (distance between two openings) is less than the minimum BWP length.

That said, I think Jar was trying to get an answer regarding total width of bracing along a BWL, for which insufficient information is provided to calculate.
 
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classicT said:
hat said, I think Jar was trying to get an answer regarding total width of bracing along a BWL, for which insufficient information is provided to calculate.
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Fail it at plan review until they give you approvable plans.

jar546 said:
what is the minimum length of bracing required when using Method Wood Structural Panel Sheathing for the braced wall panels?
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Then 48"
 
steveray said:
Fail it at plan review until they give you approvable plans.
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I don't believe that Jar is providing a real example, but is on a fishing expedition to see what we all will post in response to his line of questioning. Building up content on the forum.
steveray said:
Then 48"
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Again, that is the minimum width of a single WSP unit. The minimum length of the bracing requires calculation 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).
 
classicT said:
Again, that is the minimum width of a single WSP unit. The minimum length of the bracing requires calculation 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).
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Yes...but the minimum it could be IS 48"
 
steveray said:
Yes...but the minimum it could be IS 48"
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Not really. Need to have at minimum two panels.

R602.10.2.2.1 Location of Braced Wall Panels in Seismic Design Categories D0, D1 and D2​

Braced wall panels shall be located at each end of a braced wall line.
Exceptions:
  1. Braced wall panels constructed of Method WSP or BV-WSP and continuous sheathing methods as specified in Section R602.10.4 shall be permitted to begin not more than 10 feet (3048 mm) from each end of a braced wall line provided that each end complies with one of the following:
    1. A minimum 24-inch-wide (610 mm) panel for Methods WSP, CS-WSP, CS-G and CS-PF is applied to each side of the building corner as shown in End Condition 4 of Figure R602.10.7.
    2. The end of each braced wall panel closest to the end of the braced wall line shall have an 1,800-pound (8 kN) hold-down device fastened to the stud at the edge of the braced wall panel closest to the corner and to the foundation or framing below as shown in End Condition 5 of Figure R602.10.7.
  2. Braced wall panels constructed of Method PFH or ABW, or of Method BV-WSP where a hold-down is provided in accordance with Table R602.10.6.5.4, shall be permitted to begin not more than 10 feet (3048 mm) from each end of a braced wall line.

R602.10.2.3 Minimum Number of Braced Wall Panels​

Braced wall lines with a length of 16 feet (4877 mm) or less shall have not less than two braced wall panels of any length or one braced wall panel equal to 48 inches (1219 mm) or more. Braced wall lines greater than 16 feet (4877 mm) shall have not less than two braced wall panels.
 
classicT said:
The end of each braced wall panel closest to the end of the braced wall line shall have an 1,800-pound (8 kN) hold-down device fastened to the stud at the edge of the braced wall panel closest to the corner and to the foundation or framing below as shown in End Condition 5 of Figure R602.10.7.
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Wouldn't #2 allow the "center panel" with hold downs and 1 panel?
 
Varies depending on the height of the wall.

1693502946343.png

a. Linear interpolation shall be permitted.
b. Use the actual length where it is greater than or equal to the minimum length.
 
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