Attic Vent Repair - Keep Animals Out of Your Attic
Here's another example of an easy modification to guarantee squirrels will lose their interest in entering your home. This is an attic vent repair done for a home that had a long time squirrel problem in PA.
Even new attic vent fans have flimsy screens. Here, I fit an extra screen of 1/2 inch steel hardware cloth over the existing screen (shaped in the fashion shown) before the fan is mounted, preventing future squirrel intrusion.