How Do Norway Rats Get in the Attic?

While the roof rat may be more common in the top floors of buildings, it's also possible to see Norway rats in attic spaces. These rodents enter homes easily through broken or missing vent screens, cracks, or small holes. A common sign of their presence is gnawing or scratching sounds coming from above.

Attic Behavior

Once inside, Norway rats leave behind copious amounts of droppings and build nests by tearing up paper, boxes, and stored clothes. In addition to providing nesting materials and plenty of hiding places, attics often give rodents access to wall voids and vents, making them the ideal gateway to the rest of the house.

Damage and Dangers

Typical Norway rat behavior leads to damage in the home. Attics are particularly susceptible to the pests' burrowing, which wreaks havoc on insulated structures. Gnawing is another destructive habit. Chewed wires can cause dangerous electrical shorts, while damaged walls, doors, and windows may let in moisture and drafts.

Droppings and Disease

The feces and urine left behind by a Norway rat in an attic could spread harmful diseases. These include Hantavirus Pulmonary Syndrome, leptospirosis, hemorrhagic fever with renal syndrome, and rat bite fever. Because the attic is typically such a confined space, it is dangerously easy to inhale infected particles of waste when dusting or cleaning.

Prevention

Homeowners can use exclusion methods to keep Norway rats out of the attic:

  • Repair screens in air vents and damaged ventilation
  • Cover the crawl space with a door that fits tightly
  • Block gaps in the roof, cap chimneys, and seal entry points for pipes and electrical lines
  • Close all other access points larger than one-fourth of an inch
  • Use caulking, wire mesh, heavy cloth, copper screening and other materials as appropriate