How to Build Bat Houses for Your Garden

Bats are slowly but surely overcoming centuries of bad publicity, and the modern, environmentally-aware human is steadily growing in appreciation for the positive powers of the bat. Though they still have a lingering reputation for rabies (most bats do not have rabies), they are fantastic animals to have around the house and especially the garden. For instance, one brown bat – about the size of a human thumb – can consume about 600 mosquitoes and other unwanted insects an hour.

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They have always been revered for guano, their well-balanced poop that makes for some of the finest fertilizer out there. Recently, though, with the onset of movements like permaculture and agroforestry, they have also garnered a lot of good press for their ability to pollinate, control pests, and spread seeds. In other words, these are helpful little creatures to have around.

One of the easiest ways to help them out in return and, selfishly, is to attract them to your garden building a bat house.

The Basics of a Bat House

Most of the time when bats’ homes come to mind we either think of caves or old castles, a la Dracula and Scooby Doo. This is not without merit, as old castles and caves do make dandy bat abodes. But, bats also love to dangle on the underside of tree branches, roof ledges, and even banana leaves. In essence, they are looking for a combination of darkness, shelter, and warmth. Human-built bat houses can provide this very well.

Bat houses, as in the kind we are making, are generally thin boxes that are open on the underside so that the bats can get in and out. They have their own roofs, but they are also located in fairly sheltered areas, such as the trunks of trees, eves of homes, or tops of fences. These houses should also receive a bit of sunlight to keep them nice and cozy. If we can get these things right, we are likely to acquire some new batty friends.

The Materials We Will Need

A nice thing about building bat houses is that they don’t require all that much time, material, or skill, which makes them inexpensive and accessible.

We will need a bit of thin plywood (24 x 26 inch, 24 x 22 inch — or a 2 x 4-foot piece, which is a quarter of a sheet of plywood) and about six feet of one-by-two, cut into one 24 inch strip and two 20 inch strips. A piece of one-by-four just over two feet long makes a good roof. It’s very important not to use treated wood, as it will harm the bats.

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A few other materials would be handy. Some caulking will help seal the house up, and some dark wood stain will keep the inside dark (tea bags or spent coffee might work for a natural way to do this) but textured, while dark paint—usually black—on the outside will help to keep it warm. A handful of screws, roughly one-inch long, might not be a bad idea, either.

A few everyday tools will be required. A saw of some sort will be required to cut the plywood and boards. Paint brushes will help with applying the stain and paint. A drill makes screwing things in much easier, though it is possible with just a screwdriver, or a hammer and nails could be substituted with much more difficulty. A caulking gun might be necessary, though caulking can be found in squeeze tubes.

Putting It All Together

Once all the materials are gathered and cut to specification, we can begin putting the house together. The largest piece of plywood (24 inch x 26 inch) will be the back wall of the house, with the 26 inch length being vertical, and the other piece (24 inch x 22 inch) will be the front wall.

Stain the inside of both pieces. (We are staining instead of painting in order to leave some texture for the bats to have footing. This could be increased by adding some grooves or indents.) The front wall should have a few half-inch holes drilled into it about five inches up from the bottom to provide a little ventilation. The other wooden bits, including the outsides of the front and back, should be painted dark. (Using health-friendly, no VOC paints is going to be better for the bats.)

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Now, with everything painted, we can assemble and seal the bat house. Warning: Be sure to face the boards correctly, stain inside and paint outside.

Attach the three pieces of one-by-two to the inside of the back, first the longer piece flat at the top and then the two shorter pieces flat along the sides, leaving a small (quarter inch) gap along the outer edges so that it can be sealed with caulk. Then, seal all the cracks between pieces of wood with caulking. Lastly, the one-by-four can be attached to the top as a roof, with the bulk hanging over the front of the house.

A Few Last Points to Consider

Congrats on getting this far. A few more things to know are that the back panel is longer because it acts as a landing pad for the bats, so adding a little more texture here can be useful. Ideally, the bat house should be hung 12’ to 15’ of the ground, and this can either be on a pole, wall, tree, or something similar. When hanging, remember that a few hours of sun hitting the box is a good thing, as it’ll keep it warm.

Lastly, for those who haven’t yet built their house, obviously using repurposed materials is a great idea, and it’s entirely possible for a crafty person to produce a quality bat house with upcycled pallets, which would make the project even less expensive and more eco-friendly.

Lead image source: Deedster/Pixabay