Securing our roof against possums

Question

Possible Duplicate:
Animal in the attic (possibly a raccoon)

We have just finished a major renovation of our house. Since complete, a possum has taken up residence in our roof. Unfortunately, it is living in the floor space between the ground and first floors and we have little or no access to this area. We have sprayed "Poss-off" in as many places as possible and cut all trees next to our house to reduce access but every night he comes back. I suspect that he is either walking along the power line (although it has a possum guard, I found possum scat under it) or climbing up the pipes to our pool's solar water system (50mm).

So the questions are:

1. what more can I do to discourage him

2. if we have it professionally removed (they are a protected species), will another one just take over.

Answer 1

I had this problem in my house in Georgia with a number of animals, to solve I put my cat in the attic for a few hours a day for a week or so (usually when I was up there anyway). The cat never killed anything, (to my knowledge) but the scent of the cat drove the animals out for good. I have found this solution to be simple, cheap, and effective. It also works with dogs.