How to Build a Bat House

The goal of a bat house is to create a sheltered area that mimics the space between the bark and tree trunk where many bat species naturally roost. With that in mind, a good bat house should have the following features:

Proper Mounting - Bat houses installed too low or in the wrong location will likely be ignored by bats even if they are in the area.
Right Size - Most bat species are social and like to roost in large numbers, especially female bats when it’s time to give birth. A bat house at least 24 inches tall by 16 inches wide will be more successful than a smaller one. Bat houses with multiple narrow chambers are more likely to get used.
Narrow Chambers - Bats like tight spaces. The interior chambers of the bat box should only be ¾ to one inch deep.
Ideal Temperature - A bat house that gets too hot or too cold won’t get used. The mounting location and the exterior color of the house should be chosen based on local climate conditions to maintain the ideal temperature range for bats.
Provide Grip – The interior walls and landing platform of the bat house should have a rough inside texture which gives bats a foothold and allows them to climb up into the box and roost.

Before building or buying your bat house, ensure that you have an appropriate location to mount it.

The best place to mount your bat house is on the side of a building or on a pole. Bat houses mounted on buildings or poles retain heat better and are less accessible to predators. Even though bats generally avoid bat houses mounted in trees (more on that below), bat houses mounted in areas with good tree cover nearby (within 20-50 ft) are more likely to be used.

Once you’ve determined a good location for your bat house, there are several other factors to consider when you install it.

Height: Install the bat house at least 15 feet off the ground, preferably on the side of a building. This will give bats plenty of space to fly in and out of the house. This height also helps keep ground predators out. If you’re installing your bat house on a pole, you can also place a predator guard around the pole to make it even more predator-proof.

Orientation: Install the bat house so that it faces south, southeast, or east. These orientations provide favorable morning sun to maximize and maintain an ideal temperature in the house throughout the day and night.

Accessibility: There should be several feet of clear space in front on the box. This gives bats an unobstructed flight corridor to approach and depart from the bat box. The back panel can also extend a bit further than the rest of the walls to provide a landing platform. If the wood is very smooth, score it with a utility knife to provide a rougher texture to make it easier for bats to find grip.

Water Sources: Bats are most likely to use bat houses within a quarter mile of a natural body of water such as a pond, lake, or stream. In addition to providing a place to drink, bats often hunt for their insect prey around bodies of water.

Food Sources: All but three of the 47 species of bats found in the US are insectivorous. You’ll have the most success attracting bats if your yard is filled with native plants, which support the insects bats eat. If you’re spraying pesticides in your yard, not only do you risk poisoning the bats themselves, but you’re also killing their food sources.

Learn more about creating habitat for bats

You can find a from Bat Conservation International's website. They also have a Bat House Builder’s Handbook available for free in a digital version on their . Note that the size of this bat house is quite large: two feet wide and almost three feet tall! A successful bat house can be smaller (14 inches wide instead of 24 inches wide), but this plan is designed to easily use up a 2 foot by 4 foot piece of plywood with fewer cuts.

Properly constructed bat houses should look very different from bird houses. Bats do not roost in bird houses because their flight style and wing design require vertical access; they need to enter and exit from the bottom of the structure, rather than from a side opening like birds.

If you’re following the Bat Conservation International plans, the supplies needed are:

1/4 sheet ( 2' x 4' ) 1/2" AC, BC, or T1-11 (outdoor grade) plywood. DO NOT use pressure treated wood.
One piece 1" x 2" (3/4" x 1 1/2" finished) x 8' pine
20 to 30 1 1/4" coated deck or exterior-grade Phillips screws
One pint dark, water-based stain, exterior-grade
One pint water-based primer, exterior-grade
One quart flat water-based paint or stain, exterior-grade
One tube paintable latex caulk
1" x 3" x 28" board for roof (optional, but highly recommended)
Black asphalt shingles or galvanized metal (optional)
6-10 7/8" roofing nails (optional)

A collection of woodworking tools and materials is presented on a plywood table.

Tools Needed to Build a Bat House

Table saw or handsaw
Caulking gun
Variable speed reversing drill
Paintbrushes
Phillips bit for drill
Tape measure or yardstick
Scissors (optional)
Staple gun (optional)

For those of you who do not normally buy wood, here are some tips:

Try to purchase Forest Stewardship Council certified wood and/or recycle scrap wood.
When you buy a piece of wood that is advertised as 1 inch by 2 inches, it is not actually that big when you measure it. It's more like 3/4 inch by 1 1/2 inches. That was important for me to know because it allowed me to use scrap wood for part of the project.

In addition to the supplies on the plan, we also recommend the following:

Two clamps for clamping wood while you saw or drill
Safety glasses for when you use power tools
A small broom for sweeping sawdust

Time commitment: 30 minutes

Measure and mark where you need to cut the wood according to the plan. Clamp it down to a sturdy spot for safety. You cannot safely hold the wood and the circular saw. Adjust the blade to the correct depth depending on the width of your wood. It takes only five cuts. Don't forget your safety glasses.

At this point, you can even take the wood and lay it together to get a sense of how it will look. You'll see that the bottom piece is the biggest. The 1x2 inch pieces form the sides of the bat house and then there are two smaller pieces of plywood on top. The gap between those two is a ventilation slot.

A large slab of unpainted plywood is shown, as a comparison, next to a stack of cut and measured plywood to be used for a bat house.

Time commitment: 2 hours

A collage of four images showcasing the measuring and cutting of plywood using woodworking tools such as an electric and hand saws.

This may be the most difficult part of making the bat house, but it's the most important. The goal is to take the plywood, which is very smooth, and roughen it up to provide places for the bat to crawl up into the house. You can do this by cutting grooves into the wood.

When it comes time to cut the grooves, it can be challenging to know what type of tool to use.

A circular saw set to 1/16 of an inch can be a great choice to speed up the process. Simply re-clamp the plywood and start cutting grooves into the backboard. Keep in mind that these grooves do not have the be perfectly straight.

Once you finish the process of cutting grooves with the circular saw, you may find it useful to also take a hand saw and deepen some of the grooves and make them rougher.

Time commitment: 1 hour

With a soft brush, sawdust is swept off slabs of plywood. Each piece is then hand painted with a dark walnut brown stain.

Bats like it dark inside their houses so it's important to stain all inside parts a dark color. First you have to sweep all the sawdust carefully from the backboard, especially from the grooves that you cut.

It's important to use stain rather than paint because paint would fill in the grooves you just cut. Stain just soaks into the wood nicely.

It only takes two coats of the stain, and the stain dries fast if you are making your bat house outside in the sun.

Time commitment: 30 minutes

Before adding the side pieces, apply caulk. This seals the bat house to help keep the heat inside. Baby bats need a warm home - reaching 80 to 100 degrees Fahrenheit in July.

Next you use your power drill to attach the side pieces. Since these pieces are rather narrow, they can easily split. A way to avoid splitting is to pre-drill the holes with a drill bit that is smaller than the size of your screw. Then, when you drill in the screws, they go in much easier and your wood stays whole.

Pieces of painted plywood are screwed together using an electric drill. Caulking is applied to provide heat insulation for bats.

Time commitment: 30 minutes

Next, attach the top two pieces of plywood. First caulk to ensure a snug fit. Then follow the same advice for drilling and attach the larger of the two top pieces.

Before you attach the smaller of the two pieces, measure to make sure your ventilation slot is about half an inch.

Two side-by-side detail images of the bat house building process. The plywood is screwed, caulked, and getting ready for final assembly.

NOTE: Ventilation may not be necessary in cold climates (< 85 °F average daily July high temperatures). In that case, the front of the bat house should be a single, 23"-long piece. In these climates, bat houses may also benefit from a partial bottom to help retain heat. Slope the sides and bottom at an angle of 45° or greater to reduce guano build-up. Leave a 3⁄4" entry gap at the back and be sure the bottom does not interfere with access to the front crevices. A hinged bottom is required to permit annual cleaning.

Time commitment: 15 minutes

To ensure there are no gaps between all these pieces of wood where heat could escape, leaving our poor bats shivering in the cold, put some caulk all around the sides in any gaps that you see.

Finally, add a piece of wood to the top to form a roof.

A detailed view of an electric drill securing a final piece of plywood to form the roof of the bat house.

Time Commitment: Variable given paint drying time

Finally, we need to ensure the bat house lasts a long time, so we prime and paint it. We prime it with an exterior primer that discourages the growth of any plants or mold. Once the primer dries, you can begin painting.

The color of paint you should use will be determined by how hot summers get in your area. This is because the exterior color of the bat house can drastically influence the temperature inside the box—you’ll want to keep the bats cool in hot areas, and warm in cold areas!

To determine the best color for your bat house, first and enter your ZIP code. Scroll down and find the High Temp for July. Find your color based on that temperature below:

Average July High Temperature	Bat House Color
<85 °F	Black
85 – 95 °F	Dark to medium shade or unpainted wood
95 – 100 °F	Medium to light shade or unpainted wood
>100 °F	White

Time commitment: 20 minutes

Bat houses should be mounted on poles or buildings, which provide the best protection from predators. Wood or stone buildings with good solar exposure are excellent choices, and locations under the eaves often have been successful. All bat houses should be mounted at least 12 feet above ground, but 15 to 20 feet is better.

We hope you enjoy building your bat house, whether it's in celebration of bats at Halloween or any time of the year. Remember, once you put up the bat house, it may take a few years for a bat to find it. They will come looking in the springtime, so ideally it should be hung by late winter.