This has to do with both so I'll post under SIP as well. I plan on a house with ICFs up to the second floor deck which will be steel joists, metal deck and concrete (w/ hydronic radiant). From the second floor deck up i'd like to switch to SIPs for the second floor walls and roof. Exterior finish will be white cedar shingles on horizontal strapping (on both the ICF and SIP walls) The question is how can I align the exterior face of the SIP and the exterior face of the ICF so there is no "jog" in the wall plane. It seems part of the SIP would be perched over the foam of the ICF and not have bearing. If I pour the slab out to the outer face of the SIP I won't have a space for insulation for the slab edge (which is my "rdiator" and would be nice to keep cozy). ANy thoughts on this detail?

Birdman;

you could choose to use one system or the other (balloon frame) and hang floor system from interior, giving a fully insulated wall envelope

Use a 'Tapered Top' form for your last course with the taper to the outside. This will give you bearing to the outside face leaving about a half inch of foam at the top. It lacks the insulation on the outside but will still have 2 1/2" on the inside.
Paul Stevens