Is there a preferred approach for doing the rim band/joist area that minimizes thermal conduction?

Please see A Winning Rim Detail. That is one way.

Another option is to eliminate the rim band entirely and put the joists on joist hangers attached to a continuous SIP wall.  This is sometimes described as "balloon framing".  There was a detail drawing of that on a section of this website somewhere, but it seems to have been removed.  It was a collection of articles by a SIP-loving architect.  Used to be in the learning center, but they recently redesigned the website and now I can't find them anymore.  But the same drawing is out there elsewhere; ask your SIPs manufacturer.  The detail is a little different with OSB vs. steel skins.  The OSB detail I've seen has a panel seam at the top of joist level, and the joist hangers penetrate into the seam and screw into a horizontal 2x member at the top of the lower SIP, and then hang down and screws into the inner OSB skin.  The second story panels then sit on top of that.  So there's a seam, but no rim band.  I think you can also do it seamless with OSB by attaching a 2x ledger to the inside that the joists attach to.  I think the ledger would be screwed all the way through to the outside skin, which does create thermal bridges from the fasteners.  (Not a huge deal.)

By the way, I was describing joists for a second-story floor, where you have SIPs walls above and below.  Makes less sense for a floor over basement or crawlspace, or where the first story is ICF.

There seems to be a fair amount of wood (about seven inches in the diagram) going from inside the structure all the way to the outside of the structure when using the described approach. For a high performance structure, isn't that a concern?

This method is a big improvement over a standard Rim. More insulation and nearly air tight. It's not perfect though. You could add Styrofoam on the inside and in between the TJI's for a more robust solution.

If you are looking for something a little better, as suggested, try hanging the floor from the walls.

Is it possible to "balloon frame" an entire 2 story wall from foundation to roof and then add a rim board to the inside of the wall for supporting open-web floor trusses on the second floor?

I searched around for some drawings based on the comments above and found the following for the first floor:

Insulspan first floor wrapped deck drawing

Murus first floor wrapped deck drawing

And the following for the second floor:

Insulspan second floor wrapped deck drawing

Murus second floor wrapped deck drawing

My wife wants a two story Victorian with a walk out basement so I'd like to do as much as reasonably possible to minimize heating and cooling requirements. (I'd be content with a cave with some south facing windows.)

one of the things that we have done in the past and seems to be very effective and inexpensive is that you bring the panels down past the joist to the plate on top of the sill plate just have to have to either make the foundation wall thicker of go with a brick ledge to allow enough room.

Could either the "winning rim detail" or the setup like in the "insulpan" link be done going from a 8" ICF basement to a 6" SIP? I'd like to do this, but I'm wondering if there is enough room to do it on top of the ICF wall, or if a brick ledge facing the inside of the wall could work to add extra space so that both SIP and IJoist fit.

You could certainly hang the TJI's from the ICF wall, but to get your ceiling height, the wall would need to be higher. You may be able to place both the SIP and TJI's on the top of the wall. It all depends on how your engineer designs it. I believe that the TJI's need a minimum of 3" of bearing surface.

Panelcrafters,

The Engineeri designing this house is me! And I am an Industrial Engineer with a civil PE working in Highway construction, so I have no experience in this field!
So any help is welcomed!

Thanks!

Ok. I have seen engineers design it so that the edge of the sill plate was installed flush with exterior face of the foam. On top of that was the SIP bottom plate(1/2" in), and the exterior edge of the SIP ended up flush with the foam. Using something like that with an 8" core ICF(2" of foam on either side - 12" total), and a 6.5" SIP, you have plenty(5-1/2") of bearing area on your plate. With 3-1/2" of that above the concrete core of the ICF.

Yes, this is what I'm planning on doing. My ICF wall is 12.25" thick with 2.25" of foam and a 7.75" concrete. The SIP is 6 7/8" thick, so that's bearing on 4 5/8" of the concrete, leaving me with 3 1/8" of concrete for the Joists.

I am tempted to move the sill plate in 1" and flash the 1" of foam that will stick out, that way my SIP will have 5 4/8" of bearing, with the Joists on 2 1/8" (I was planning on putting a protective barrier on top of the ICF anyway, in addition to the sill sealer)
My Joist supplier checked with the Joist manufacturer and they said that I only need 1 3/4" of bearing for the joists. I was surprised by that. That just somehow seems like too little.

Thanks!