Primarily Petroliana Shop Talk Forums Non-Petro Discussions Non-petro Discussion and Showcase Different kind of ? about mice in garage.

I live along the edge of a wooded area and I have had mice in the garage. I removed anything and everything that they may want to live in and all materials that they may want to build a home with, and a little help from Decon, and since have had no problems.
So I have your typical wook framed construction garage with 2 x 4 walls and 2 x 8 roof rafters with 3/4" plywood roof sheeting. I've never seen it done before, but I want to insulate the ceiling space between the 2 x 8 rafters and then enclose the space, or install a ceiling of 1/4" plywood. I'm pretty sure I can enclose things quite tightly, but mice can get into almost anything if they really want to.
So here is my question. Are mice going to get into the space and set up camp? Is there any reason to believe that they would invade this space any more than they would or could the walls?
Your thoughts?
And to the construction guys out there, what, if any kind of venting would need to be added if I enclose this space?