Shear transfer with ship sheathing
Shear transfer with ship sheathing
(OP)
In the northwestern U.S., and presumably elsewhere, where it is popular to use cedar shake roofing, it is common to install this over skip sheathing. Rather than lay down a full plywood diaphragm on top of the rafters, 1x4 or similar boards are run perpendicular to the rafters and are spaced apart approximately 9 to 12 inches to allow the shakes to be nailed to them. My question is how is the lateral shear transferred to the walls? Is the nailing of the skip sheathing boards to the rafters enough, or is there typically some sort of additional diagonal bracing installed?
Thanks in advance,
Tom W
Thanks in advance,
Tom W






RE: Shear transfer with ship sheathing
RE: Shear transfer with ship sheathing
RE: Shear transfer with ship sheathing
Tom W
RE: Shear transfer with ship sheathing
I saw an engineer do an analysis on spaced cleats with variable nailing patterns similar to the analysis of metal diaphrams. I suspect it was for the purpose only of justifying a stable model rather than anything more than that. I think the practice defies rational analysis.
Old houses used spaced sheathing different from the nailers used for shakes. That old spaced sheathing was maybe 4 inches wide with 1 inch gaps. I think the code provides a diaphram shear value for this.
RE: Shear transfer with ship sheathing
It isn't a very big moment capacity per connection, but there are a lot of them, and it adds up. AITC has an example calculation in their Handbook.