We live in a duplex and in our basement the copper pipes run parralel along our joists just beneath the first floor above. There is a large header running perpendcular just beneath the joists resulting in a very large exposed area between units along the 10" joists. Unfortunately we have a rodent issue where rats can cross back and forth between the joists from out unit to our neighbor's. I'm in the process of blocking the area off between each joist with lumber to prevent passage between units. In other words, when you reach up and stick your arm through this area from one side your hand is visible on the other side inside our neighbor's basement. But in one area we have about four pipes running along the joists which is making it very difficult to block off.
What materials can come in direct contact with copper pipes that won't result in corrosion and eventual leakage and failure? I was thinking of some type of metal netting that rats can chew through. But I'm concerned the metal in whatever I use might corrode the copper pipe since whatever I use will have to be in contact with the copper pipes to create a barrier for the rats. Great Stuff foam isn't an option as they (rodents) eat right through this. Also, is there a type of caulk that is safe to be in direct contat with copper pipes? Some of the pipes run vertically up between our shared wall. The holes drilled in the wood to allow the pipes to run through are large enough for rodents to fit through and get into our walls. Is there a copper safe caulk I can use to seal off these openings to prevent them from getting in?