Bats can sometimes be seen leaving their roosts to feed in the evening. They often enter homes through the eaves, vents, soffets, or siding. Droppings (guano) can sometimes be found in attics, crawl spaces, or on the roof, or siding. With bats there is a slight rabies concern and the guano can cause respiratory problems.
Bat exclusion requires going around the entire building and sealing any potential entrances, while providing the bats with a "one way door" that they can exit and not return through. All bat work comes with a warranty guaranteeing that the building will be bat free for a period of time.