24 foot exterior wall

[rktect 1]

Wall bracing method #3

A 2nd story addition. One wall, 24.5 feet wide. 2 double windows (around 6 feet wide) each located 3.5 feet from the corners. Leaving plus/minus 7 feet between the windows.

I told the dp he needed two 4 foot wide panels at each corner or 8 feet of panels in the middle. He needs to move windows one way or the other.

He said that if he placed one 48 inch wide panel in the center, then he has complied with the min. code as that panel will be located within 12.5 feet from both ends.

So, is he correct? Only one 48 inch wide panel dead center.

Is there any prescriptive option out there for the 3.5 foot wide alternate method next to a window on the 2nd story?

 

[mtlogcabin]

Look at TABLE R602.10.1 WALL BRACING and the AMOUNT OF BRACING a, d, e

Located in accordance with Section R602.10 and at least every 25 feet on center but not less than 16% to 75% of braced wall line depending on wind, seismic and which story it is and what it is supporting.

Does the first floor have enough shear to support the 2nd story addition?

If the precentages are met I think he might be ok.

 

[Mule]

R602.10.4 specifies EACH braced wall panel shall be at least 48" in length.

R602.10.4 Length of braced panels. For Methods 2, 3, 4,

6, 7 and 8 above, each braced wall panel shall be at least 48

inches (1219 mm) in length, covering a minimum of three

stud spaces where studs are spaced 16 inches (406 mm) on

center and covering a minimum of two stud spaces where

studs are spaced 24 inches (610 mm) on center. For Method

5 above, each braced wall panel shall be at least 96 inches

(2438 mm) in length where applied to one face of a braced

wall panel and at least 48 inches (1219 mm) where applied

to both faces.

I don't know if the submitted plans would comply.

Unless the exceptions apply.

Exceptions:

1. Lengths of braced wall panels for continuous

wood structural panel sheathing shall be in accordance

with Section R602.10.5.

2. Lengths of alternate braced wall panels shall be in

accordance with Section R602.10.6.1 or Section

R602.10.6.2.

 

[GHRoberts]

He said that if he placed one 48 inch wide panel in the center, then he has complied with the min. code as that panel will be located within 12.5 feet from both ends.So, is he correct? Only one 48 inch wide panel dead center.

Is there any prescriptive option out there for the 3.5 foot wide alternate method next to a window on the 2nd story?

His math is right. The APA has options for narrow panels.

 

[north star]

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rktect1,



What is the height of the top plates? Table R602.10.5 lists different widths of

wall bracing panels if the plates are taller than 8 ft.



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[rktect 1]

standard 8 foot heights.

 

[north star]

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rktect1,

Here is a link to an updated Wall Bracing handout from the APA. See if this helps.

http://www.apawood.org/pdfs/managed/G440.pdf?CFID=10418567&CFTOKEN=11753838

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[Mule]

Now if he uses the "narrow wall windbracing then it may be okay and the walls are continuously sheathed. However it doesn't sound like he is.

 

[bgingras]

I went through this with a garage last year, the engineer stamped what I had already drawn which was a 4' panel between 2- 8' doors on a 24' wall. He specified a nailing patter of 6" O.C.

I've accepted the single 4' panel for these walls in the past. I'm now hearing that MA may completely wipe out the braced wall section in the new code anyway.

 

[FredK]

I'd say he's ok.

 

[Builder Bob]

Just a country boy...

IF I understand wall bracing, I beleive the second floor wall bracing can be reduced since it isn't supporting as much of a load...... The first fllor would require more wall baracing due to the loads being imposed from the structure above.

A good example of this concept is used in skyscappers, the strucutral steel for the lower floors is extremely large, when you near the top, the steel has been drastically reduced.

It has been a while since I used the IRC, STD-1099, and the WFCM....

Just trying to ensure that minds are open.....

(P.S. let me know if I am still n track after being out of residential plans since the 2003 IRC....)