Wednesday, June 3, 2009

Re: the use of T1-11 Siding Plywood

Ken,

Yes, you can use T1-11 and other grooved siding patterns for shear panels.
The two most important things to remember are:

1. The effective thickness of the shear panel is the thickness that
the nails are driven through. Panels are usually 5/8-inch thick with
5/16-inch deep grooves. If you nail through the thin part of the panel
along one edge (where the adjacent panel overlaps) then you can only count
the 5/16-inch thickness.

2. The "quick way" (pronounced "WRONG way" by engineers and the APA)
to install panels is to nail only three sides of each sheet of plywood.
The edge that will be overlapped by the adjacent panel is not nailed, and
when the adjacent sheet is installed it overlaps and "captures" the previous
panel--but provides no shear transfer capacity. APA's publication
"Design/Construction Guide--Diaphragms and Shear Walls" (their Form No.
L350F, probably still available at their website) shows this very clearly.
To make sure there is enough room to nail both edges of plywood,
you may want to specify wider studs behind panel joints (this is essential
if you have wide grooves and need the full 5/8-inch panel thickness for
shear capacity).

See Section 3.4.14 of "Wood Framed Shear Wall Construction--an Illustrated
Guide," available at www.shearwalls.com and fine bookstores everywhere.

Best wishes,

Thor Matteson, SE

> From: ken ng <zy7up@yahoo.com>
> Subject: the use of T1-11 Siding Plywood
> To: seaint@seaint.org
>
>
> Can I use T1-11 exterior plywood sheathing for shearwall?=0AIf yes, would=
> =A0that mean I=A0would not=A0need plywood or OSB sheathing for my
> shearwall=


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