Bat Houses
Build

Build


Little brown myotis are in flight around a bat house
Little brown myotis using a bat house. Credit: Mark and Selena Kiser

Building your own bat house is a great way to get involved in bat conservation. Bat species worldwide are experiencing habitat loss, and building an artificial roost can give our bat friends a safe and comfortable place to live. Here on our website we have designs for three different types of roosts - single chamber, four-chamber, and rocket boxes. Volunteers with BCI’s Bat House Research Project (1993-2004) conducted research on hundreds of bat houses and other artificial roosts, and the designs linked on this page incorporate the most successful features identified in those tests. These bat houses are designed to accommodate 14 different species of North American bats.

The correct bat house for you depends on available tools and lumber, your skill as a carpenter, your budget and your expectations. You can, of course, modify your bat house to adjust for location-specific factors, such as climate and the preferences of local species.

The most successful bat houses have roost chambers at least 20 inches tall and at least 14 inches wide. Taller and wider houses are even better. Rocket boxes, a pole-mounted design with continuous, 360°chambers, should be at least 3 feet tall (see Figure 6 on page 14 of the Bat House Builders Handbook). All houses should have 3- to 6-inch landing areas extending below the entrances or recessed partitions with landing space inside.

The number of roosting chambers is not critical, but in general, the more chambers the better. Single-chambered houses should be mounted on wooden or masonry buildings, which helps to buffer temperature fluctuations. Houses with at least three chambers are more likely to provide appropriate ranges of temperature and better accommodate the larger numbers of bats typical of nursery colonies. Two single-chamber houses can be mounted back-to-back on two poles to create a three-chamber bat house.

Bellingen Flyout
Jadyn, 10 years old, proved herself a very
capable woodworker (with a little help from her
grandpa). Credit: Woodworkers Guild of America

 

Bat Conservation International worked with the Woodworkers Guild of America to develop some bat house building instructions and videos! Click here to check out this great resource! 

 

 

 

 

 

Construction

Building a bat house
Building a bat house Credit: Janet Tyburec

For single-chamber and nursery houses (Figures 3 to 5), 1⁄2-inch (or thicker) exterior plywood is ideal for fronts, backs and roofs, while 1- or 2-inch-thick boards are best for the sides. One-inch (3⁄4-inch nominal size) cedar or poplar lumber is recommended for rocket boxes. Roofs for any roost type can be built of 3⁄4-inch exterior plywood to increase longevity. Cover roofs with shingles or metal for extra protection. Plywood should have a minimum of four plies for durability. Using 3⁄8-inch plywood for roosting partitions reduces weight and allows more roosting space for a given house size.

Pressure-treated wood contains chemicals that may be toxic to bats and should be used only if sealed by painting. Alternative materials, such as plastic or fiber-cement board, may last longer than wood and require less maintenance.

Coated deck screws or other exterior-grade screws should be used instead of nails to assemble houses. Staples used to attach plastic mesh should not protrude from the backs of panels and must be exterior grade or galvanized to prevent corrosion. All seams must be caulked, especially around the roof, prior to painting. Latex caulk is paintable and is the easiest to use.

Color Recommendations

The temperature of your bat house greatly affects whether or not bats will take up residency. Since the color you paint the roost affects the amount of light it absorbs, you can influence the box’s internal temperature. Consult the map below to figure out what color will work best for your location.

Bat House Color Recommendations
Bat House Color Recommendations and Average Daily High Temperatures in July

        1. Blue areas: less than 85˚ F. – Black or dark shade of paint.     

        2. Green areas: 85˚-95˚ F. – Dark or medium shade of paint.       

        3. Yellow areas: 95˚-100˚ F. – Medium or light shade of paint.

        4. Light pink areas: 100˚ F or greater. – White or light shade of paint.

 

Resources

For more information about constructing, painting, installing and maintaining your bat house, please see:

 

Further Reading From BATS Magazine

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