OSB sheathing and seam blocking

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Old 11-12-13, 11:30 PM
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OSB sheathing and seam blocking

Not sure if this is the right area but I'm putting up my sheathing on an addition. Ever since I have been working in construction jobs, I have been using 2x6 nailer blocking (button boards) on the seams of the wall sheathing. It's the way I was shown so I do it the last way I was shown. But over time, it has come to my attention that the size of the blocking depends on the size of the stud framing. 2x4 for 2x4, 2x6 for 2x6 and etc. There's not much to find in the code on the subject so I was wondering what others have to say about it.
 
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Old 11-13-13, 03:50 AM
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If this is on a wall I've never seen anyone use blocking at the seams.
Fire blocking if the walls over 8" tall yes. But not in other cases.
Not going to do any harm except slightly compress the insulation in that area.
 
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Old 11-13-13, 05:55 AM
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If sheathing is laid horizontally, then yes, blocking is required (at a minumum) on structural sheathing to that the entire perimeter of the panel may be nailed. When it is oriented vertically, it is nailed to both the bottom and top plate, so you would only need blocking if the walls were extraordinarily tall. (greater than 9') 4 x 9' sheathing is available in the event that the builder does not want to install a 12" ripper across the rim joist.
 
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Old 11-13-13, 07:12 AM
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The seam nailers (blocking) are required on all seams. We're in a hurricane area. Even if we put our sheathing up vertically, it has to start at the lower extremity of the house band, right down to the crawlspace curtain wall, with a double row of nails at 3" each here. So there will be at least one horizontal seam no matter what we do. I guess my direct approach is, if I use 2x4 nailer blocks instead of 2x6, will the inspectors flinch, or worse, will my buddies call me a cheap-skate?
 
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Old 11-13-13, 05:43 PM
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So your walls are taller than 9 ft?

I think since your blocking is structural, it has to be the same dimension as the rest of the wall. If it is also going to serve as your fire blocking, it HAS to be full width or it's not a fire block. So the fireblock code trumps your idea.

Nice video: Institute for Business & Home Safety
 
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Old 11-13-13, 07:08 PM
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No, the walls are 8 feet. The sheathing must connect the top plate to the point where the girders meet the piers so the sheathing covers a little over nine feet vertically bu only 8' of studded wall is involved.
I'm still combing through our code. The valla at the lumber supply said that I should find a requirement for the nailers. It's buried deep if it's in there.
 
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Old 11-14-13, 06:20 AM
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The only thing I can find is that the nails must be 3 inches on center at the seams. I would assume that best practices or common sense must apply when choosing the width of the nailer boards to make sure that the nails have plenty to bite into.
NC Residential High Wind Requirements
 
 

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