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Re: Plywood Roof Diaphragm Connections

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Title: RE: Plywood Roof Diaphragm Connections
Always provide blocking at 2x truss / rafter bearing locations. Period. If there is no frieze blocking, where does the roof diaphragm terminate? (All diaphragm boundaries are required to have edge nail pattern). Cross grain bending is not a good idea...  W.T.C.A. has no good testing on cross grain bending through a plated truss heel, thus everyone uses blocking.
 
Pat Clark, P.E.
-----Original Message-----
From: Zachary Goswick <ZachG(--nospam--at)angusyoung.com>
To: 'seaint(--nospam--at)seaint.org' <seaint(--nospam--at)seaint.org>
Date: Wednesday, October 17, 2001 3:06 PM
Subject: RE: Plywood Roof Diaphragm Connections

When I use a holddown anchor such as a hurricane series anchor by Simpson Strong Tie, I use the nails in each truss to transfer the shear load down through the truss and into the anchor.  I pick an anchor that can handle the forces.  If I can't get the nails to work alone, I have been placing blocking between the trusses to help transfer the load.  My next question is how big the heel depth can be before I have to provide blocking, if the nails and anchor both work?  In other words, how big can the heel depth be before I have to start considering weak axis bending of the truss and the flipping of the trusses onto their sides?

Zachary Goswick