I assume you mean in the attic. I've been there. This is what you need to do:
1. Go up there with a respirator, and figure out where they're getting in.
2. Put live (humane) repeater traps up there or several single animal traps.
3. Close up any holes especially around vents with steel wire mesh.
4. Decontaminate the attic if there's a lot of urine and feces up there.
or
5. Hire someone do to all of the above.
then
6. Go outside and trim back any trees or tree branches that are within a few feet of the roof, and cut off any vines that are growing close to or onto the house.