Q:

How do I stop bats from nesting in an attic?

What is the best way to discourage bats from taking up residence in a house?

A:

I'd say the best way would be to find out where they're entering and close it off. If it's open for ventilation use something like a chicken wire that will allow the air to easily flow through. 

A:

A pest control contractor supplied me with a box of a copper mesh material that could be stuffed into cracks that were serving as entry ways for bats (when they were known to be out).    It looks somewhat like a very course steel wool, but in copper.    It doesn't rust, so it doesn't discolor siding, and is flexible, but doesn't stay compressed if you squeeze it.   It worked well for our place where bats were following the channels in our vertical siding into a cavity behind the fascia boards.

