Bat houses should be at least 60cm tall and thick enough to accommodate two or more roosting compartments/chambers, separated by thin vertical baffles. Larger bat houses provide better insulation, so they tent to be more successful that shorter/thinner designs.

The chambers should be 1.9 to 2.5 cm thick (bats like tight spaces). All baffles should be roughned, so that bats could grip on them better. Since bats have only one little claw per wrist to cling with when they land, there must be 8 - 15 cm tall roughened landing area at the bottom of the bat house.

Tall: min 60cm

Wide: min 31cm

Landing area: 8-15cm

Space between chambers: 1.9 - 2.4 cm

Grooves apart: 0.635 - 1.27 cm

Grooves deep: 0.156cm

Step 1: Wood Cutting

Take a 480 x 19.2 x 2.2 cm wood (cost around 10 euro) - best choice is cedar or exterior plywood. Be sure to use untreated wood.

Cut out:

Front part: 3 pieces 40 x 19.2 cm

Back part: 4 pieces 35 X 19.2 cm

Sides: 2 pieces 70 cm height (width depends on the thickness of the inner baffles)

Inner baffles: 2 pieces of thin plywood 36cm width

Roof: 1 piece 44 cm

Step 2: Putting Grooves on the Back/inner Pieces

Grooves apart: 0.635 - 1.27 cm

Grooves deep: 0.156 cm

There are two ways to provide rough surfaces within the house and on the landing pad: score or groove the surface using a saw or other sharp implement to make shallow cuts.

If you cannot cut grooves in the wood, staple UV-resistant durable plastic mesh (0.3 to 0.6 cm) firmly to the wood.

Step 3: Inner Compartments

The chambers should be 1.9 to 2.5 cm thick (bats like tight spaces). All baffles should be roughened, so that bats could grip on them better. Since bats have only one little claw per wrist to cling with when they land, there must be 8 - 15 cm tall roughened landing area at the bottom of the bat house.

Step 4: Painting, Caulking and Screwing on the Sides

Bat house can be made of exterior plywood, cedar or pine. All exterior surfaces should be coated with an exterior-grade water-based paint. Bats like it dark inside their house, so it's important to stain all inside parts a dark color.

Before screwing the sides together, apply caulk. Put some caulk all around the sides in any gaps that you see. This seals the bat house to help keep the heat inside.