Getting rid of a colony of bats from an attic or other structure involves observing where they are entering and exiting the structure, and then sealing those points to prevent return. If there are only a few bats in the structure, they can be removed by an animal control professional.
The best way to remove a bat from the house is to allow the animal to exit on its own by opening a window. Large numbers of bats roosting in a building require professional assistance.
The recommended location for a bat house is on a pole or building at least 15 feet high facing south or southeast to maximize sun exposure. Trees are not recommended due to the potential for predators and branches blocking the entrances.
Clean up any existing hiding places, and lay down moth balls to prevent incursions by bats. To find existing bat roosts, look for signs of their entry points, locate the points, install exclusion netting, and seal up the entry points while the bats are away hunting.
To get rid of bats in winter, identify the exterior areas where the bats enter and leave the house and cover them with bat screening, leaving the bottoms open. Wait for the bats to evacuate their roosting place and then secure the bottoms of the screening.
You can build a simple bat house in a few hours. For materials, you need a 2 foot by 4 foot section of exterior grade plywood, a 6 foot length of 1-by-2-inch board, 1/2-inch deer netting, caulking, exterior latex paint in a dark color, 3/8-inch staples and 1-inch and 3-1/2-inch deck screws.
A bat house must include walls, a roof and an opening on the bottom for bats to enter, as well as horizontal grooves inside the house from which bats can hang. Make a simple bat house with plywood or cedar, galvanized screws, silicone caulk and staples.
As of October 2015, free bat-house plans are posted online by This Old House, Bat World Sanctuary and Bat Conservation International. This Old House offers moderately difficult plans that take three to four hours to complete. The site also has a video that demonstrates the construction.
To get rid of bats in your attic, first inspect for bats and observe their activity, and then seal all but one or two main entrances. Make these one-way entrances. When all bats leave, seal the main entrances. This should not be done during the summer to avoid trapping babies.
Bats build nests in walls, behind the chimney, along the roof-line and in the attic. When not in flight, bats hide in small places in a house. This can often include any area large enough for the bat to fit.