One of the critical aspects of the work that we do for homeowners is to use our experience and knowledge to track exactly where every entry point is located. This is the first step of rat-proofing. You will almost certainly be amazed at how dexterous rats can be; we’ve even seen them scale stucco walls. They are more than capable of squeezing through an opening that is about the size of a dime, enough to fit their head in, and then the body will follow. Just looking for a large opening and trying to seal it up is never going to solve the problem entirely, as rats are much more cunning and covert.
There have been many jobs that we have done where the homeowner and the pest control expert before us have been totally baffled as to how the rats are getting into the property. This is why you need an expert in your attic who knows where to look and what to look for.