Squirrels are rodents and famous for chewing on anything, and when they get access to your attic, it is common to see them chewing on wiring — almost 95% of house fires caused by squirrel invasions in attics. In addition to wiring damage, squirrels can cause significant damage to a home's insulation and even damage the structural integrity of your house. Squirrels use insulation material for nesting; in severe cases of squirrel infestation, they will urinate and defecate all over insulation and destroy it.