Thank You for your responses. The project is a tall open building with frames at 4'-6" o.c. The intent is to design each frame to take out it's own share of the horizontal forces. Being a light single story building with a lot of wind area, I expect that the wind loads will govern.
Regarding SIPS, I have been unable to get any shear values from the manufacturers that apply to spiking or screwing through an entire panel to a timber frame. All of the testing I have seen is based on both skins being nailed to a 2x plate recessed into the bottom of the panel which would require access to both sides of the panel. This is rarely the case when applying panels to a timber frame.
The plot thickens. Chris
