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RE: to block or not to block?

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Wouldn’t you need to have some type of wood member between the trusses at the top of the truss heel to nail the top of the wall sheathing to?  That would basically be the same as having conventional blocking wouldn’t it?  Different load path, but just as effective I would say. 

 

As a related topic, I’ve been trying to get away from using truss blocking as my shear transfer path.  I try and use the lateral capacity of hurricane clips on trusses (without heels) whenever possible.  I think it’s questionable to get any shear strength from a piece of vented blocking that has half it’s area drilled out.

 

Eli Grassley

PSM Engineers

Seattle

 

-----Original Message-----
From: Joe Grill [mailto:jgrill(--nospam--at)swiaz.com]
Sent: Thursday, November 04, 2004 2:17 PM
To: seaint(--nospam--at)seaint.org
Subject: to block or not to block?

 

I was going home last night by a route that I normally don’t take.  A house under construction is just about closed in and I noticed that instead of blocking between the ends of the roof trusses the contractor had just sheathed over the ends of the trusses.  At first I wasn’t too surprised as construction around here can turn up all kinds of strange things, but then I thought…why not?  These are manufactured residential roof trusses, with plated panel points, almost parallel top and bottom chords and heel depths of about 24” from what I could see as I drove by.  I noticed hurricane clips where the sheathing hadn’t been applied yet.  But, if the sheathing is nailed per what would be required to transfer the shear from the roof diaphragm to the wall plate, such as a shear wall would be nailed, wouldn’t that be adequate to restrain the trusses from rolling over?  It appears that the shear transfer would be there.  Kind of like a really short shear wall.  Just a question for discussion.

Joe grill

 

Joseph R. Grill, PE (Structural)

 

jgrill(--nospam--at)swiaz.com