I have a two year old two story with walkout ICF house - ICF all the way up. Since moving in, we have had a continual problem with mice in the walls, so much so that we even cut an access hole in one lower area where the baseboard goes to clean out dead mice. They seem to love this one spot. The part of the wall they are in is interior stud, but we are at a loss on how they are getting in. Any ideas on how to track this down? Next step is to cut a huge hole in the sheetrock wall to investigate, but I'd love to avoid this. HELP! We get them primarily in this one spot, but also have seen evidence of them in the attic and we hear them seemingly IN the ICF wall in the room under the garage (formed by Lite-deck forms). Granted, we are on 25 acres in the middle of a corn field, but how in the world are they getting in the house?

A mouse can enter through a very small opening.  This might help http://www.howtogetridofstuff.com/pest-control/how-to-get-rid-of-mice/.  Good luck.
Bruce

Further research into this last night appears to have confirmed that the mice are knawing into the enterior foam and must be creating vertical pathways all the way up to the attic (30' higher!) since I can see perfectly round openings at the wall edge in the spray in foam in the attic that covers the gable walls and rafters. Amazing. More research. We have the Platon dimple fabric drainage mats against the foundation walls. At the mats topmost edge, a layer of stucco was applied overlapping the mats by about 8" and goin up behind the siding about 8". This bridges the gap between grade and the siding. It seems that in some places, the stucco has been pulled away from the house by the (settling?) Platon, which tore. So...I've got a few places with torn Platon exposed that has created easy access to the foam. Question: How do I remediate? Is the 'easiest' way to dig out around the house a couple feet, remove the bottommost course of siding, reapply an overlapping layer of Platon, reapply the stucco, re-attach the siding, and put the dirt back?

Though I have not seen a lot of posts on the issues, some ICF systems start below grade and have no barrier in the insulation on the outside all the way to the rafters.  Whatever you have on the exterior on top of the ICF (e.g. fake stucco, siding, etc) is not in place below grade.  Therefore all a mouse has to do is burrow underground where the ICF has no barrier, burrow up 30 feet to the top of the second floor and then they are in the attic.  There are no doubt once in the attic a place to squeeze through a spot in the attic and fall all the way down between the drywall to the floor.  With no way out they die there. 

There are some ICF systems that have an exterior barrier that prevents pest from burrowing all the way to the top.  Remidation for ICF systems that don't have that would be a good question.  I would like to know too.  I wonder if my ICF system has the same issue.  Did find one mouse in the wall once time and the only place they could have dropped down from is the attic.  I imagine that even if they could not scale a wall they certainly would have other access points to get up there as well.  Seems more likely though that they would burrow their way up to the attic through the exterior ICF insulation and then they have pretty free access.

Hope that helps