Common Rodent Entry Locations
Rats can enter an opening the size of a half dollar (about ½ inch). Mice can enter openings much smaller. To keep rodents out, you will need to find and seal ALL access points. Carefully check the perimeter of your home for any openings, including:
Gaps around doors and windows, including garage doors. Poorly-fitting windows and doors should be replaced or repaired. Windows that are opened should have screens. Look for any gap you can put your thumb in – that’s a large enough gap for a rat to squeeze through.
Cracks in foundations and walls. Be sure to check all the way from the ground to the roof, since rats can climb straight up most vertical walls.
Openings to the roof, including vents and chimneys. Chimneys should have caps to exclude rats and wildlife.
Vents to crawl space and attic. All vents should have a tight-fitting cover with openings smaller than ½ inch.
Openings where pipes, wires, and cables enter the home. These openings can be covered with ¼ inch hardware cloth, sheet metal, or cement filler. Rats can often gnaw through spray foam filler.
Openings in roof or eaves. At the junction of roof pitches, there is often an opening that may allow rats to access the attic. Missing or broken roof tiles should be replaced.
ats do not want to move out of your comfy home and will look for other access points once they have been excluded. Continue closing access points until you are sure the rats are no longer getting inside. It may take time and patience to locate and close all openings to your home, but fortunately these repairs are generally simple and inexpensive.
How Norway Rats Enter the Home
Norway (sewer) rats have the ability to enter the home through the sewer lines. They find breaks in drain pipes caused by faulty joints, poor construction or by tree roots. Norway rats will burrow through the ground and will emerge into yards, under sidewalks, driveways, and enter buildings.