How to Build a Bat House

This simple one-chamber roost will give those beneficial bug-eaters a much-needed boost. Here’s how to build a simple bat house.

WHAT YOU’LL NEED TO BUILD A BAT HOUSE

• 1⁄2″ x 30″ x 36″ sheet of exterior plywood (Don’t use pressure-treated plywood; it’s toxic to bats)
• 1⁄2” x 26″ x 36″ sheet of exterior plywood
• 1″ x 4″ x 40″ board for the roof
• Two 1″ x 2″ x 24 1⁄2″ boards for interior frame
• 1″ x 2″ x 36″ board for interior frame
• Four 1″ x 2″ x 3″ wood spacer blocks
• Crosscut saw
• Pocketknife
• One quart of dark exterior water-based stain
• 53 1″ exterior wood screws
• Seven 1 5⁄8″ exterior wood screws for the roof
• Drill
• 1⁄2″ drill bit for vent holes
• 3⁄32″ drill bit for screw pilot holes
• Countersink bit so screws are flush
• Phillips screwdriving bit
• Two squeeze tubes of exterior, paintable caulking
• One quart of exterior water-based primer
• Two quarts of exterior black or gray water-based paint
• Paintbrushes

WHAT YOU’LL DO TO BUILD A BAT HOUSE

Step 1: Cut out all the bat house boards.

Step 2: Use your pocketknife to scribe shallow grooves (less than 1⁄16″ deep) across the inside of the back sheet of plywood, about 1⁄4″ to 1⁄2″ apart. The grooves help bats grip the plywood.

Step 3: Run a bead of caulk onto the contact surfaces of the interior frame and spacer blocks, and then screw them in place. All surfaces that are in contact with each other should be caulked before screwing them together. Caulking acts as a gasket, sealing out water.

Step 4: Drill 1⁄2″ vent holes. In cold climates, you need only three or four vent holes.

Step 5: Stain the interior of the bat house, including the plywood, frame and spacer blocks. Allow the stain to dry.

Step 6: Caulk and screw the back panel to the frame and spacer blocks. Be sure to drill pilot holes to avoid splitting.

Step 7: Caulk and screw on the roof. A drop of caulking in each screw pilot hole will help waterproof the bat house and keep the inside dry.

Step 8: Paint the exterior with primer, then apply two coats of paint. Use black paint for colder climates and gray paint for warmer climates. Attach the bat house to a building or other structure. Face it south or east, about 10′ to 12′ off the ground.