I've been through this and remember it all too well. We had many mature black walnut trees on the property. We had absolutely no problems with grays but when the reds moved in, the grays moved on. The reds are just too aggressive. The house only had about a 2" soffet but it was solid, formed by a 2x10" top plate on a 2x4 wall. They chewed right through the 2x and the face board. Metal sheets were a waste of time. I just ended up with more plates and more holes. Sounded like marbles rolling around because they pulled walnuts into the attic, tore up the fiberglass insulation and chewed through the 2x8 ceiling joists where there was flooring in the Attic. Sounded like marbles rolling around on the sheet rock ceiling.
I tried the rat traps. It worked for a while but they learned it wasn't a free lunch and never touched them. Someone told me to try rat poison and that they'd go outside to die. Maybe they did but I can tell you one didn't
Good thing I had no children at the time because I couldn't find the bugger and we moved into another bedroom until the remains dried out - about a year
Moth balls, nothing more than marbles to them and more noise not to mention the stink - hate those things. Havahart traps ... nope, they learned them too. Lead poisoning at ~ 900 fps was the last resort and the only successfully method. 11 all told. 12 counting the one that got into the house and met the tribe of cats - cats left me a hind quarter and tail and were really happy to show me too
Last one was smart an took me most of one year to get. I'd bang on the wall and ceiling, they'd head to the exits, I'd grab the 22 and pop the first one I saw. The smart one wouldn't stop and high-tailed it (literally!) about 250 feet to my brush pile where it would launch itself into the pile and not move a mussel. I can still see the expression on its face thru the scope when it made a mistake and stopped to see were I was. That was that. Grays moved back and life was in harmony again.
Now I'd try Critter Ridder
as a repellent. Kept them off the bird feeders and out of the bulbs and plants by the mailbox garden. Smells like black pepper. I've tried quite a few of Havahart's
products with success every time. Not cheep but when you think of how much you spend and never see a thing, it has added value