Peppermint oil and chilli powder are two of the things popular in the UK to try to keep squirrels who want to be roomies at bay. Tends to work for most rodents.You could place two or three mothballs near/in/by the hole that needs fixed. Hang them in an old sock/onion bag, in the way so they have to push them out of the way if they try to go back in, or just drop them on the floor where they are coming in. (More mothballs than that and people won't be able to stand to be in the rooms below.) Since its not a confined space, you'll have to replace the mothballs if it takes very long to get the repairs done, so you need to keep an eye on them.
I had a grey squirrel around the bord feeders in my garden last week and was thinking of trapping him but then he would have to be euthanised because they are trying to reduce the numbers to help red squirrels make a comeback. I couldn't do that to him so just chased him off if I saw him. He was quite brazen though and tried to out stare me before he scooted - as if to say "Don't waste your time - I'll be back!"