For DIYers who want to build their own bat house, you can either find a prefabricated kit to assemble at home or build one from scratch using online specs. Home and garden centers often sell the kits, as do many online retailers. Regardless of where you get your materials, check whether the bat house is certified by Bat Conservation International. This certification ensures that the bat box has met minimum comfort and safety specifications for roosting boards and landing pads. For most at-home builds, a single-chamber bat house will be sufficient since it holds up to 50 bats.
To make your new bat house a more inviting and cozier place for bats to roost, it should face sunlight for at least six hours a day and be sealed to prevent drafts. Mount the house a minimum of 12 feet above the ground and any internal chambers should have a maximum width of ¾ of an inch to protect the bats from predators.
Lay out all bat house parts and fasteners to ensure you received everything you need. A single-chamber house has several wooden pieces, including a back section, a smaller top front piece, and a smaller lower front piece; all of which will have grooves on the inside face. The kit will also include two side pieces and furring strips of multiple lengths to support the sides and roof, which should be the final step. Screws are supplied for assembly; however, you may want to weatherproof with caulk.
Dry assemble the bat house to make sure that everything fits nice and snug before you caulk and insert the screws. Place the back piece with the inside up, lay the furring pieces along the sides and the top, then lay the top and lower front pieces in place. There will be a small 1/4-inch gap between these two tops, for ventilation. Depending on whether the top is one or two pieces, put the roof in place. If everything fits as it should, then prepare to secure it with caulk and screws.
Remove the roof and the two top pieces of the bat house. Apply caulk to the bottom of the furring pieces and secure them with a screwdriver or electric drill using a Phillips head bit. Apply caulk to the top of the furring pieces and position the front pieces — top and bottom — into place. Secure them with the included screws. After caulking the top support pieces, attach the roof to the bat house.
Add caulk to all the exterior seams on your new bat house, including the sides, the roof, and all the screw openings where the sections are connected. This will prevent any drafts from affecting the temperature inside the house. Bats do not like cool homes and may not return if it is not warm enough for their young ones.
Once the caulk has dried and set, usually overnight, it is time to prep your bat house for painting. Using a water-based, exterior grade primer, cover the exterior sections of the house with an even coat and allow to dry. This will ensure a better surface for the paint to adhere to and give you a better-looking house.
Once the primer has dried, stain or paint the bat house in the color recommended for your area, to best maintain an internal temperature between 85 and 100 degrees Fahrenheit. For northern areas that are cooler during the summers, a darker color will absorb more heat from the sun and help maintain a warmer internal house temperature. For southern or warmer climates, use a lighter color.
Once the paint has dried, you are ready to install your bat house. For best results, the house should be installed on the side of a 2-story home or a standalone pole at least 12 feet from the ground, within half a mile of a water source, and facing towards the sunlight. The height allows bats to drop from the roost and catch air beneath their wings so they can start to fly. Do not install on a tree, as this makes the bats easy prey as they freefall from the house.
Now you are ready for your new bat house grand opening, but depending on the time of year, it could take up to several years before you see any new residents. Since bats hibernate during the colder months, consider your grand opening more of a soft opening. Check for guano on the ground beneath the house or use a flashlight during the daytime to look up into the house for bats.
If you don’t see any residents in your new bat house after 2 or 3 months, check to make sure there are no known predators, like wasps or cats, around the house preventing the bats from choosing your neighborhood. If everything is good with the surrounding area, try adjusting the location of the bat house.