Smooth concrete to us is like a rock climbing wall, to a mouse. I have seen them climb surfaces that seemed smooth, but they have little, pointy claws and since they don't weigh much, they don't fall off. I have a 2nd floor porch and am planning to replace some weatherstripping because I noticed a small gap when a beetle entered. Then, there's the fact that they can jump.....they can squash themselves through a 1/4" thick gap, which is about the smaller dimension of the weep holes.
So, no nesting material?