The large bat house provides many roosting options and is ideal for larger nursery colonies of females and young. It is also a good idea to horizontally groove inner surfaces for footholds or attach non-metal screening to provide toe holds. This is also important for landing areas below the entrance. Caulk all outside seams to limit air flow. This helps trap the bats' body heat inside the house.
Sealants approved for aquarium or kitchen use are best.
Place tar paper or dark shingles on the top and 4 to 6 inches down the side to increase inside temperatures. Nursery roosts often require temperatures of 90 degrees F or more. A dark stain also helps increase the temperature. Hang houses 10 to 15 feet above ground. South and southeast exposures are best for providing maximum thermal gain.