BTW,
When we put the SIPs on my house, the installation procedure required nailing a 2x3 bottom plate around the house (cantilevered somewhat beyond the foundation), over which a grove in the bottom of the SIPs slid. The mfg'ing tolerances of the SIPs (and the pre-existing roof overhang in places) made fitting the SIPs over the supplied 2x3's somewhat trying at times. The guys helping me asked if we really needed that 2x3 btm plate, since the SIPs were also being screwed on 6" centers to the side of my 8x8 timber bottom plate. In our application, the 2x3 was clearly redundant, but I said "yeah, we absolutely need that 2x3, it's there to keep the insulation from sliding out after the OSB rots."
-Thomas
