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# Re: Wood: 'en' and Plywood question.

• To: seaint(--nospam--at)seaint.org
• Subject: Re: Wood: 'en' and Plywood question.
• From: "Mark T. Swingle" <mswingle(--nospam--at)earthlink.net>
• Date: Thu, 15 Jul 1999 01:34:15 -0700

```Dennis:

Re point 1):  YES
I assume you mean demand, not capacity.  I agree with
your math, and I will just put it another way so that we
are both on the same page:  If v is the shear in plf, and
you have plywood one side with nails at 6" oc, the force
per nail (demand) is:
V=(v pounds/foot)*(6 inches)/(12 inches/foot)
= v/2 pounds per nail [same as your v*(6/12)].
If you have plywood two sides with nails at 6" oc each
side, AND THE TOTAL DEMAND IS STILL v, then
the force per nail is
V=(v pounds/foot)*(6 inches)/(12 inches/foot)/(2 sides)
= v/4 pounds per nail per side [same as your v*(6/24)].

Re point 2):  I always specify 15/32" or 1/2" 5-ply (struct I).
I believe that the G values are the same for 15/32" and for
1/2", and also I believe there is not a difference in the code
tables between 5-ply and 3-ply sheets.  Many engineers do
not specify Struc I, and VERY few specify 3/8".  A previous
post on this topic indicated that for OSB one should use
plywood values.  So, in summary, I think you would only
have 2 values that are typically applicable:  1/2" Struc I
and 1/2" CDX.  I'm sure there will be dissenting opinions.

Mark Swingle, SE
Oakland, CA
------------------------------------------------
Dennis Wish wrote:

> 1) I know this is an elementary, but I want to make sure I have it right. If
> you sheath both sides of the wall using the same nail pattern (who wouldn't?)
> do you reduce the nail capacity in half?
>
> For example if you have 8d at 6" on the edge on one side, the capacity per
> nail is v*(6/12) per nail. However, if both sides are sheathed with 8d at 6"
> o.c. is the capacity per nail v*(6/24) ?
>
> 2) What thicknesses of plywood and OSB are commonly used for shearwalls. I
> always specify 15/32" 5-ply (struct I) panels but understand that some use
> 3/8 or 1/2". With all of the choices for plywood's to determine wall
> deflections, which panels should I be considering for common use in all of
> the area's of the US (since the program calculates wind loads as well).
>
> I forgot to take this into consideration on my spreadsheet program and need
> to add it. Any advice would be appreciated.
>
> Thanks
> Dennis
>

```