I have so many questions. My next one deals with the thickness of a foundation. I'm planning to use 4.5 inch SIPs and my posts (which will rest on the deck) will be 8x8's. Does my foundation have to be 12" thick or can I go with 8" thick walls and have the SIPS hang over the outside edge of the wall (and seal underneath them) or should the posts be only partly supported by the foundation? (even though there will be solid blocking between them, it seems the later would put too much stress on the joists.)