Bill I 'm with you!
Before I started shooting squirrels they had chewed through my attic, roof, had nested in my attic (!!), also like you chewed their way through the attic fan from outside and chewed the plastic on the electrical fan wires(!). They even chewed the vinyl mesh around the chimney cap and fell down the chute into my TV/family room. Had 2 of them run around the house. That's when I knew I didn't have steel wire mesh around the cap and called the guy up because I had ordered it with steel mesh.