Every year a tree next to my house drops an above average amount of acorns, the rodents seem to find their way back into my house. My goal this year is to stop that. I am caulking, foaming, replacing, poisoning, etc. I dont think they have made it to the main floor, but I have found dead mice in the basement and I hear them in the attic.

I think they maneuver through the joists through the abnormally large holes cut for the copper (heat pipes) in the floor joists (looking up from the basement). I was wondering if I could spray foam each hole, so only the copper goes through. I wanted to make sure that didnt stress the pipes. Can anyone comment on this?