Bats will continue to return to a roost, especially one that is long-established, so providing them with a new place to roost nearby, such as a bathouse, increases the chances that they will take up residence there instead of inside your house. Since their homing skills direct them back to their favorite points of entry—in our case the gap between the chimney bricks—Jim positions a bat house as close to the old "bat door" as possible. The higher you can install a bat house, the more likely it will be effective; minimum height is 15 feet above the ground. Though small, the cedar bat house can accommodate a colony of a few hundred. By late spring, we should know if the bats have fully adopted the bat house as their new home.