Use Cedar Shake Roof as a continuous diaphragm?
Use Cedar Shake Roof as a continuous diaphragm?
(OP)
Hi guys. Here's the problem:
I'm working on a large custom single family home on the east coast and it requires a full IBC lateral design. The owner is looking to use a traditional cedar shake roof, which uses 1x4's across the rafters to support the shakes instead of using plywood/osb roof sheathing. Normally, you would count on the roof sheathing as your diaphragm to transfer the lateral loads to the gable end shearwalls. However, in this case, I don't know that I can call the roof a continuous diaphragm without the plywood. Also, there are no published diaphragm values that I could find for a roof framed in this configuration.
Ideas?
I'm working on a large custom single family home on the east coast and it requires a full IBC lateral design. The owner is looking to use a traditional cedar shake roof, which uses 1x4's across the rafters to support the shakes instead of using plywood/osb roof sheathing. Normally, you would count on the roof sheathing as your diaphragm to transfer the lateral loads to the gable end shearwalls. However, in this case, I don't know that I can call the roof a continuous diaphragm without the plywood. Also, there are no published diaphragm values that I could find for a roof framed in this configuration.
Ideas?






RE: Use Cedar Shake Roof as a continuous diaphragm?
ht
there is a design option for continuously sheathed roofs, and still considered "traditional" shake. I'd say that this would be the best way to go for a full lateral design.
Here's the full manual:
http:
They also say they've tested the system using plywood sheathing but not OSB.
I hope that helps a bit...
RE: Use Cedar Shake Roof as a continuous diaphragm?
Garth Dreger PE
AZ Phoenix area
RE: Use Cedar Shake Roof as a continuous diaphragm?
http://www.atcouncil.org/pdfs/atc7-1toc.pdf
I also have seen it described in the Western Woods Use Book chapter on designing for lateral forces.
RE: Use Cedar Shake Roof as a continuous diaphragm?
2. on the west coast, where the APA-EWS supervises most of the plywood / osb sheathing, APA-EWS will support he use of properly rated OSB as equivalent to properly rated plywood for lateral support.