Hello all, I was wondering if any of you have experience finishing an ICF basement. I have read a ton about proper basement finishing on the Building Science Corp site (Hi Dana) and it seems I should be able to omit their recommendation for adding rigid insulation to the exterior walls, so I could frame directly against the interior of the ICF foam. Is that how you guys have done it? How about the floor? It seems like they recommend 6 mil poly, then 1" of EPS/XPS then a couple of layers of OSB. I was thinking of going with 3/4" Advantech. Do you just tapcon that through the foam and poly? Do you use sleepers and attach to that? Glue it? Fully Floating? I have a plan for the stairs but need to sort out the added floor height for my walk-out patio doors. How would you guys handle raising the flooring height that much? The threshold of that patio door isn't going to allow for it. Thanks in advance for the help Matt

Technically you could just mount gypsum to the surface using adhesive and screws into the cleats in the foam.
This always struck me as a Bad Idea, as it makes repairing, remodeling, or rebuilding after a disaster tougher since you have to literally rip off the surface foam.
So a sleeper or OSB/Ply base might be a more future-proof option.
Unfortunately, ICFs are still "new" enough that you don't see a lot of "I have pre-existing ICF, what are my remodeling/recovery options?" out there yet.

Another finish I'm seeing is essentially stucco'ing the interior insulation. Again, it's basically a more or less "permanent" finish as removal will likely result in damage to the insulation substrate.

Generally, a moisture barrier/damp-proofing should be applied to the OUTSIDE before backfilling. Usually some sort of peel and stick. And a capillary break should have been used at the base of the wall to prevent moisture wicking from the foundations.

I am definitely going to frame a wall on the inside; the question is am I going to put another 1" of rigid foam on the ICFs before I frame the wall?

I have both a roll-on barrier and dimple board on the exterior of the basement walls. I have drainage and pea gravel on the inside and outside of the footings. The basement is bone dry but I do have concerns about condensation of moist air etc. There is nothing 'under the wall' so to speak as my basement was monopoured

There is no point to adding more foam or vapor barriers on the between the interior EPS and the non structural framed wall. At 2" Type-II EPS has a vapor permeance of about half that of latex paint on wallboard, and at 3" it's nearing Class-II vapor retardency. Any moisture coming from the ground via vapor diffusion though the foam won't accumulate- dries to the interior.

If the purpose of the additional foam is thermal performance, the studwall can be insulated with unfaced fiber insulation, adding another ~R8-R10 to the whole-wall performance (assuming 2x4, R11-R15).