Things You'll Need
Rats are a big problem for many households, but their size makes it easier to determine an entry point. Once you realize where the rats are entering from, it's a simple process to block off the hole. You should continue to carefully store your food and clean your house regularly. This may prevent a repeat infestation through another entry point. Regularly monitor your patch to ensure the rats aren't working on penetrating your new defenses.
Measure the length and width of the hole you suspect the rats are using. Measure the width of any pipes running through the hole as well.
Cut a piece of sheet metal that is large enough to cover the hole using a grinding wheel. Drill a hole large enough to fit around any pipes in the way as well.
Disconnect the pipes that reach into the hole. Slide the piece of metal onto the pipe. Replace the pipe and slide the piece of metal flush against the hole.
Install screws through the metal and into the wall to hold the piece of metal in place. This creates a strong barrier against the rats. Caulk around the pipe to prevent the smaller pests from squeezing through your defenses.
For very small holes (no more than two inches wide), fill them with steel wool. The rats can’t easily chew or crawl through the steel wool, so it acts as an effective deterrent.