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Re: Wood:"en" and Plywood question.

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In a message dated 7/16/99 10:10:13 AM Pacific Daylight Time, ECVAl3(--nospam--at) 

<< Dennis,
 Because your reaction to the concept of using 3/8" CDX plywood (structural 
 II) for common shear walls was somewhat puzzling, I checked with a few of 
 local lumber yards and found that it is a common shear wall call-out here in 
 the central coast of California (sometimes referred to as the Middle 
 Kingdom). It's possible the 1997 UBC required design loads will increase the 
 shear panel requirements such that 3/8" panel values will no longer be 
 compatible but in the past it it was used extensively in this area.
 According to one lumber yard, OSB  is commonly used as a "Performance Rated" 
 substitute for CDX.
 ECVAL3 >>

My concern was for the abuse of 3/8" - 3-ply and other 3 and 4 ply panels. 
This is a hugh problem in my area due the excessive overnailing. I have made 
it a practice of specifying 15/32" 5-ply (Structural I) panels or Strutural I 
OSB which seems to be readily available in this area. There is a note 
regarding overnailing issued by APA which, in 5-ply panels allows for 20% 
overnailing as an acceptable maximum. Unfortunately, I have seen a real abuse 
in this area out here in the desert. Primarily, the sheathing is installed by 
a subcontractor who provides minimum wage labor and gives them the gun and 
let's them loose on the job. These subcontractors have two modes: 1) Full 
power which exceeds the 20% overnailing allowance and 2) no power - where the 
heads stick up 1/16 to 1/8" above the panel and need to be hand nailed (my 
The other major problem is that the subcontractor believes that it is always 
better to install more nails than is called for since nails are cheap and 
will often install certain panels 2 to 3" on center - risking both a split in 
the stud or a reduced capacity where 2x studs are installed.
Yes, in case you wonder, I am specific in my details and notes that the 
contractor is not to deviate in any way from my plans without my approval. I 
even included special notes regarding nailing and conventional framing on my 
framing plans, general notes and included in the details. So that they will 
be sure to use Common nails, I have a detail that shows the full size nails 
so that the contractor can place the nail against the detail to verify the 
shank diameter and head area. 
Still, I have not had one job where all of the precaution was followed - 
regardless of pre-construction meetings or special notes.
Unfortunately, it is not until the panels are already installed and nailed - 
when I do a structural observation - that the problem is evident. At this 
time, I can demand they take out the panel and replace it (and thus possibly 
damaging the studs) or inspect what has been done and hope that I can make it 
figure (except for less than 3" nailing).

Sooooo. I am surprised by engineers who allow for 3 and 4-ply panels 
(especially 3/8") to be used - not condemning, just surprised.