Rats are a nasty problem as not only do they cause scratching at night in your attic, which might startle you, but they also spread a ton of diseases. As a bonus, you might little gift of feces left all around the area. Dealing with them is not as easy as one might think, however even an untrained person can do it. We are going to outline the process in a few steps and provide you with all of the info you would need to have, which we have gathered over the course of years.
Step #1: Identify the entrance points a rat uses to get inside the building. This is the most important task, without it we cannot continue. There is certainly a point of entry for the rat to be able to reach the attic. All points of entrance must be found. Inspect the whole building and we really mean the whole, the vents, roof joints, and chimney. From the ground up to the roof, be thorough. Signs of the rat using a certain location as an entry are grease, brown stains, gnawing, and others. Another thing you could do is track the evidence a rat leaves in the attic and see where it leads.
Step #2: Seal all of them up regardless of the rat's location. Doesn't matter if it is inside or not, sealing up everything is especially important if you have a more than a single rat. This allows you to limit the rat's movement to a single area and allow you to do exclusion.
Step #3: Use one of entry points to set a trap, in order to remove the rats. There is a good variety of traps you could use; we recommend that you use a live cage, which will ensure that the rat won't die in the process of removal. We understand that the rat breeds incredibly quickly and could cause a lot of damage to person's property, however why should you do it, if there are better alternatives. In case you don't care we suggest you use a lethal snap trap, which instantly kills the creature, without causing any pain.
Step #4: Check the traps occasionally to dispose of caught rats and avoid any odor problems. There is no particular bait you should use, as rats simply don't care. Our experience has shown peanut butter to be a good choice, but we leave that entirely up to you.
Step #5: Begin the cleaning process of your attic. This is just as important as step 1. Rat feces are known to cause health problems, and you want to decontaminate and deodorize the whole area without sparing any resources. Not only does that enable you to use your attic again, but rats actually leave strong pheromones behind which will attract new rats and you will end up having the same problem again.
As you can see, there are quite a lot of things that you might want to take into proper account when it comes to it.