"Until you wake-up hearing rat fur rubbing in the walls behind your head board at night, hearing them chewing on the framing near your bedroom window at night, or the framing of the stairs you won't know how willing you are to use poison."
Agree with the above. Had rats in former house in Houston. Strongly recommend hiring a professional exterminator and closely following their advice regarding ingress/egress and sealing. FWIW, we had an exterminator for the Houston rat problem and 75% of their work was ingress/egress evaluation. They used snap traps to eliminate the rats once the holes were addressed.