Step1

The first thing you have to do is think like a rodent! They circle the outside perimeter of your building trying to locate entry points, and you must do the same thing.

Step2

As you inspect the building you are trying to locate any openings where pipes or cables may be entering, even if a few feet off the ground. Smaller openings can simply be stuffed with steel wool and covered over with plastic wood putty, cement or exterior caulk.

Step3

Look closely along the bottom of all entry doors, and don't forget the lower basement door, if you have one. The general rule is that if you can slide a pencil under the door, that would allow enough room for a mouse to squeeze in, a rat would need a little bit more room. If their head will fit under, the rest of their body will follow. For space under doors you can install a heavy duty rubber weather-strip  Hollow weatherstrips will simply get a hole chewed through, or possibly build up the height of the threshold.

Step4

For any holes or cracks near foundation perimeter, where it meets the cement, you can use broken up glass or steel wool mixed in with some cement to seal the opening. A rat can chew threw most anything, and wet cement is no problem. The steel wool or broken glass in the cement or sealer, when ingested, will serve to cut their intestines, cause internal bleeding and death.

Step5

If you find holes in the earth near the foundation, you will have to go inside, like the basement for instance, and try and locate the final entry point(s) into the building and seal off there. Holes like this will usually represent the travel of rats and will usually have more than 1 tunnel or entry point. Mice do not commonly travel or enter this way. Either can be traced by following a dark track left behind if this entry point has had extended use.

Step6

A rodent can scale up certain porous surfaces, such as rough brick, rough sawn wood, or climb a cable wire to gain height, so check around your lower window frames for any openings. Seal off with wood putty, steel wool or caulk.

Step7

If there is a garage connected to a home, you need to check the garage door for a tight seal to the ground when closed, space at the outer edges or corners of the door, the general outside perimeter of the garage, the entry door going into the home and any openings for wiring or piping traveling through the common wall of the garage and home. If rodents continue to chew the seal, try braided hose or flashing to resist them.