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RE: Wood Shear Wall Nailing

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This is about a week late, but I thought I would throw my two cents in. Back in the 80’s when we were doing seismic retrofits we found that in full size lumber 10d Common nails could split a full 2x member. The problem was the placement of the nail on lapped sheathing or and the clearance to the edge of the member. Common nails have a larger shank diameter and larger head. When dealing with shear, the depth of embedment was not as much an issue as the shank diameter since even Simpson has an N10 nail in various lengths that conform to the code required shear values on structural panels.

 

It became my practice to follow Gerard’s standard of specifying only 8d Common nails. At one point I even included a full size detail of all of the common nail sizes so the contractor could place a nail up to the detail to assure that the head and shank diameter matched the detail if he had any questions. The problem, of course, was that the framers would call in a sub to nail up the panels and these guys would get paid by the board feet or panels nailed. They always seemed to believe that it was best to over-nail rather than to take the time to verify spacing and it became evident that with 10d common nails, they would invariably split a member or nail them too close. The other issue, of course, was the use of a four ply 3/8” plywood panel instead of a 5-ply 15/32” or ½” panel.

 

To make it short, I decided to rely on my specifications and details. If they got it wrong and I spotted it, they had to correct it. I was spending so much time checking for crushed ply’s, sinkers vs. commons and all of the other problems associated with observation that it would defeat the purpose over the long run. When brought to the attention of the city in an observation report or to the GC who relied on his framer (uncertified guy with a power nailer and an attitude that anything he nailed lasted longer than the Pyramids), I ended up getting into more fights than it was worth. If it failed or performed poorly, at least I spec’d it out properly and attempted to correct it. In more than one case I charged to redesign and never got paid – only got threats from owners who understood his contractor rather than the code or his technical speaking engineer.

 

I think we do the best we can, but the reality is that when conventional construction (IRC or prescriptive) is added to the argument, the issue becomes the bottom line of the code – will it hold up well enough to protect lives and get people safely out? Beyond that we hope for good and competent contractors who know how to read our specifications and details, but as I get older and crankier I get the feeling that we are losing the war.

 

8d Common nails as per my shear wall schedule – them’s the standard on my drawings. No 10d’s (especially on KD Lumber) and even more so on retrofits that had already been nailed once. If I keep it at 8d Common with 5-ply panels then I can allow some leeway in the quality control issues.

 

Dennis

 

From: Gerard Madden, SE [mailto:gmse4603(--nospam--at)gmail.com]
Sent: Tuesday, July 22, 2008 10:23 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Wood Shear Wall Nailing

 

FWIW, I always use 8d nails for shearwalls without too many problems. Most of the phone calls I get are in regard to Sill Nailing getting confused with "Shear Nailing"

Contractors see "SN" on a schedule, equate that as shear nailing (Known as Edge Nailing to us engineers) and complain that I'm making them uses SDS screws and 16's into studs.... then I explain that they need to re-examine the details...

"EN points to the nail on the wall sheathing into the double top plate. SN points to the vertical nail from the sole plate into the blocking or rim joist"....


"Oh"

-gm

On Tue, Jul 22, 2008 at 12:59 PM, Drew Morris <dmorris(--nospam--at)bbfm.com> wrote:

Michel Blangy wrote:

I am curious as to whether your wood shear wall schedules are based on 8d,
10d or both nails. I have avoided calling out 10ds out of fear that 8ds
would be mistakenly installed. I am being irrational?

Michel

No, although I prefer to use 8d on the walls and 10d on the roof sheathing.  What concerns me
most is that whether they are using common nails or galvanized box nails, the only two types
listed in IBC Table 2306.4.4 for shear walls.  Who knows what they use in nail guns.

We had a project several years ago where a church addition was being framed by volunteers who were overseen by a supposedly experienced foreman.  We called out 8d common at various spacings and I saw a wide variety of nails (roofing, 8d, 6d sinkers, etc.) being used.  They were however nailed at the exact spacing called out on the plans.  Once this was straightened out, they used the correct nails at the correct spacing.



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