I have rats that are going to the edge of the attic where the rafter meets the floor. They are penetrating at the edge straight down and getting into the walls . what is the best effective way to prevent this? I’m thinking flashing It is still enough to pull up against that angle with after the floor meet. 

Also, I am replacing the plywood walls in a shop outback will need to replace possibly some studs due to mold and chewing good ideas for building into the return so I won’t have to exclude after they start Chewy holes?