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RE: shear ply over gypsum

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John Rose wrote:

 Yes, it's in the wood structural panel shear wall table. Includes
> 5/8" gwb also (Type X or C gwb used for fire-rated walls).  A better
structural
> solution would be to use wood structural panel sheathing directly attached
to
> framing, with gwb over; it's permitted for fire-rated walls by footnote to
> fire-rated walls in Chapt. 7 table.  Siding of any type could be installed
over the
> gwb (e.g., a three-layer wall on the exterior side). It's UL Design U344
for
> one-hr. fire resistance from either side.  City of LA amendments for 97UBC
will delete
> provisions for using wood structural panels over gwb until cyclic
> tests indicate acceptable performance.

In my opinion, this application only applies to plywood or wood structural
panels that is applied over "Gypsum Sheathing" which is not the same as Type
"C" or "X" GWB.  Gyp sheathing supposedly has a different core composition
than either regular or fire rated sheet rock.  In fact, I have always been
curious how for certain nailing patterns, you could obtain slightly higher
allowable loads for plywood over gypsum sheathing instead of plywood applied
directly to the framing.

Henry D. Kim

> -----Original Message-----
> From: John Rose [mailto:jrose36(--nospam--at)earthlink.net]
> Sent: Wednesday, April 07, 1999 6:20 PM
> To: seaint(--nospam--at)seaint.org
> Subject: Re: shear ply over gypsum
>
>
> Yes, it's in the wood structural panel shear wall table. Includes
> 5/8" gwb also
> (Type X or C gwb used for fire-rated walls).  A better structural
> solution would
> be to use wood structural panel sheathing directly attached to
> framing, with gwb
> over; it's permitted for fire-rated walls by footnote to
> fire-rated walls in
> Chapt. 7 table.  Siding of any type could be installed over the
> gwb (e.g., a
> three-layer wall on the exterior side). It's UL Design U344 for
> one-hr. fire
> resistance from either side.  City of LA amendments for 97UBC will delete
> provisions for using wood structural panels over gwb until cyclic
> tests indicate
> acceptable performance.
>
> John Rose/APA, Tacoma, WA
>
> Jeff Smith wrote:
>
> > Can anyone tell me if the 97 code allows shear walls with shear
> plywood over
> > 1/2" gyp. (I have not picked up the new code yet)
> >
> > Jeff Smith
> >
>
>
>
>
>
>