Build a Triple Chamber Bat House

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 than shorter/thinner designs.

The roosting chambers should be 1.9 to 2.5 cm thick (bats like tight spaces). To help bats grip, all baffles need to be roughened. Since bats only have one small claw on each wrist for landing, the bottom of the bat house should feature a roughened landing area that is 8 to 15 cm tall.

Height: min 60cm

Wide: min 31cm

Landing area: 8-15cm

Space between chambers: 1.9 - 2.4 cm

Distance between grooves: 0.635 - 1.27 cm

Groove depth: 0.156cm

Step 1: Wood Cutting

Use a 480 x 19.2 x 2.2 cm piece of wood (costs around 10 euros), with cedar or exterior plywood being the best options. Make sure the wood is untreated.

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

Distance between grooves: 0.635 - 1.27 cm

Groove depth: 0.156 cm

There are two methods to create rough surfaces inside the house and on the landing pad: you can either score or groove the surface using a saw or other sharp tool (eg. router or chisel) to make shallow cuts.

If cutting grooves in the wood isn’t an option, 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 to improve the grip for the bats. Since bats have only one small claw on each wrist for clinging when they land, the bottom of the bat house should include a roughened landing area that is 8 to 15 cm tall.

Step 4: Painting, Caulking and Screwing on the Sides

A bat house can be made from exterior plywood, cedar, or pine. All external surfaces should be treated/coated with an exterior-grade, water-based paint. Since bats prefer a dark environment inside their house, it's essential to stain all internal parts with a dark color.

Before screwing the sides together, apply caulk around any visible gaps to seal the bat house effectively, which will help retain heat inside.

Step 5: Things to Remember

- Ensure that all joints are properly sealed

- All wood used in bat boxes should be rough sawn (unplaned)

- Removable lids should not be used and the box should not be opened

- bats need an airtight enclosure as they will regulate the interior heat by moving up or down in the chamber