Haz,
I just got back from a "log home and timber frame" show in Lexington, KY. There was an ICF company/distributor there. After pouring my basement with 9 foot symons-panels, I can truly appreciate the elegance of ICFs now! Their system was truly amazing, and if I hadn't locked myself into SIPs with my foundation design, I would seriously consider ICFs for enclosing my timberframe now. They seem to me, better than SIPs for this purpose. No OSB - nothing to rot! You can paint stucco-like finish directly on the outer EPS shell and I can't see why it wouldn't last nearly forever. (with occasional reapplications of the textured paint)
SIPs might still have an edge though if you're trying to incorporate 8' wide windows or garage doors below a large expanse of wall. (although with a thick enough lintel and plenty of rebar, the ICFs could work there too)
In any case, I think your decision to enclose your frame with ICFs is brilliant. Please let us know how it turns out. I think the next structure I build (my garage?) will probably be ICFs with stone facing and timber frame trusses.
-Thomas
my timberframe house web page
