I worked in an old building that sometimes had squirrels get into the walls and attics, it was a heritage building with wood soffits and fascia so there was no keeping them out if they were determined, but what encouraged them to move away was every place anyone reported noise in the walls, I'd poke a hole with my jab saw and insert a few folded Bounce dryer sheets (the kind that are so perfumed that I hate even having them in the car when they're double bagged), and install a plastic access hatch over the hole... repeat every two weeks in all areas that have had squirrels though, if you just treat one area they go to another. To keep them off my balcony, I use a product called "Get off my garden" that's a very strong citronella scent they also don't like. I've even used citronella tea lights in my garden to keep the bunnies off my beans long enough for the plants to get established, hopefully it works on the groundhog that's been eating my brassicas...
I worked in an old building that sometimes had squirrels get into the walls and attics, it was a heritage building with wood soffits and fascia so there was no keeping them out if they were determined, but what encouraged them to move away was every place anyone reported noise in the walls, I'd poke a hole with my jab saw and insert a few folded Bounce dryer sheets (the kind that are so perfumed that I hate even having them in the car when they're double bagged), and install a plastic access hatch over the hole... repeat every two weeks in all areas that have had squirrels though, if you just treat one area they go to another. To keep them off my balcony, I use a product called "Get off my garden" that's a very strong citronella scent they also don't like. I've even used citronella tea lights in my garden to keep the bunnies off my beans long enough for the plants to get established, hopefully it works on the groundhog that's been eating my brassicas...