After being in the business of getting animals ouf of homes for 25 years, I sometimes think I  have seen everything when it comes to rats and squirrels entering homes,,,, but I haven’t. I am currently working on a very large home on a golf course community and it has rats. Rats do not know who you are or how much money you have. Rats are rats, they are creatures of habit, always seeking  food, water, and shelter. Food and water is abundant everywhere for the animals, so I focus on the repairs of the structure in an effort to fix the problem. Doing a bandaid approach and fixing one opening will not stop animal infestations in the future. When animals invade a structure, the solution will always be in complete and thorough repairs. This particular home is spectactular, it is very well decorated, and could on the cover of many magazines, but it still had rats. The homeowners did not do anything to attract the animals but they still showed up. This home had openings on it that were big enough for the rats to crawl right in, they did not have to gnaw on wood to make an opening. they simply found a weak link in the construction and took advantage of it. These type openings are built into the home during construction, original or addon, it doesn’t matter. Anytime a contractor is doing something to your home on the exterior shell, there is a very very good chance they are going to fix your problem, but there is also a very very good chance they will leave openings that allow animals to enter. Most of there openings are going to be in out of the way places the homeowner will not seen, but the rats and squirrels will certainly find them.  The long term solution to keeping rats out of structures will always be in the repairs. When shopping for someone like me, make sure they have a city or county business license and liablity insurance. Over the past sevral years many people have attempted to do what I do and now, there is a lot in incompatancy in the market. Some of these new people will take your money and run. they will not return phone calls because they are thieves and had no intention of completing the work. Ask for references, check them out, call the Better Business Bureau, contact the governing agency that issues the license and permits in your state. I wish you well in your search for a professional who will correct your problem, warrant their work and give you piece of mind that your home has been repaired and is safe for your family.