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Re: Plywood sheathing on wood trusses

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You usually nail perp to the sheathing  so assuming the nail is iniatiated
on the shoulder of the top chord, it is very likely that the nail will be
completely embedded in the top chord and full design values can be used.

HTH,
Rand
----- Original Message ----- 
From: "Keith De Lapp" <keith(--nospam--at)kdlengineering.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Tuesday, October 12, 2004 4:47 PM
Subject: RE: Plywood sheathing on wood trusses


> Shimming a 3/16" thickness doesn't seem practical.  Splitting would be my
> big concern.  I would take a look at the demand/capacity ratio.  If it's
> high I would require a shaped nailer along side the top chord.  If it's
not
> high I would inspect for shiners and let it go.  The situation you
describe
> is common on hip roofs.
>
> Keith De Lapp, P.E.
> KDL ENGINEERING
>   -----Original Message-----
>   From: Dennis Wish [mailto:dennis.wish(--nospam--at)verizon.net]
>   Sent: Tuesday, October 12, 2004 12:58 PM
>   To: seaint(--nospam--at)seaint.org
>   Subject: RE: Plywood sheathing on wood trusses
>
>
>   This is a tough call. I think the issue here is that the shear transfer
> through the diaphragm creates an opportunity for bending in the exposed
nail
> shaft and/or greater chance of pull-out through bending of the nails. In a
> tight connection, the bending issue is almost non-existent as the shear is
> tightly transferred from wood to wood.
>
>   So the question then comes it shimming the wood would provide adequate
> shear transfer. I would prefer to use a nailer to the side of the truss
> ripped at the angle causing the 3/16” gap and then boundary nail the
> sheathing to the nailer – like molasses flowing through the load path from
> wood to nail to wood to nail. This might confuse some, but I’ve always
> considered the Molasses metaphor as ideal in understanding load path
> transfer from roof to foundations.
>
>
>
>   Sorry about the simplicity of this – but I try to understand how the
> materials will work together in light-framing rather than to try and
analyze
> any one component.
>
>
>
>   Dennis
>
>
>
>   Dennis S. Wish, PE
>   California Professional Engineer
>
>   Structural Engineering Consultant
>
>   dennis.wish(--nospam--at)verizon.net
>
>   http://www.structuralist.net
>
>
>
>   "Apathy is Lethal!" Speak out and Vote - but make sure you getthe facts
> right without the spin from either side; Verify their claims at
> FactCheck.Org; http://www.factcheck.org
>
>
>
>   -----Original Message-----
>   From: Jim Wilson [mailto:wilsonengineers(--nospam--at)yahoo.com]
>   Sent: Tuesday, October 12, 2004 12:16 PM
>   To: seaint(--nospam--at)seaint.org
>   Subject: Plywood sheathing on wood trusses
>
>
>
>   Does plywood sheathing need to be flat against the top chord of
supporting
> wood framing to be acceptable/effective?  I have a case where wood trusses
> are not parallel to the pitch of a roof, and therefore, the plywood will
> rest on one edge of the top chord, but be approximately 3/16" off of the
> other edge.
>
>
>
>   Jim Wilson
>
>   Stroudsburg, PA
>
>
> --------------------------------------------------------------------------
--
> --
>
>
>



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