Building a Bat Box
There are many sizes, shapes and designs of bat houses. You can be creative in your design as long as the internal design meets the requirements for the bats. I have seen boxes designed like a castle, barn, rockets and so much more. You can paint or burn images on the front such as a bat or other images. Be creative in your design.
The following are some designs or shapes of bat houses.
- Traditional box shape
- Rocket Box
- Pole design
- Condo
Size
The larger the box, the better it serves the bats. This also goes for chambers. This is an example of a bat house size.
- Dimension: 17" W by 24"H
- Chambers: Minimum of 3 or 4 chambers and 3/4" to 1" gap
Larger boxes provide the bats with the ability to regulate their body temperature. Bats can move about within the box to cooler or warmer spots inside the bat house to adjust their body temperatures. Multiple chambers also provides them with more options of temperature changes. In my option, do not waste your money or time on 1 or 2 chamber houses.
Video by Bat BNB on box sizes.
VIDEO
Wood
It is important to use untreated wood or wood that is not pressurized. The chemicals used to treat wood is harmful to bats.
First, if you plan to purchase a bat house, make sure it is from a company that specializes in bat houses. Many of these agencies also donate a percentage of sales to bat rehabilitation. Please, do not buy bat houses off Amazon, E-bay or other large on-line stores. You may end up with a bat hose built by someone who has no idea how to build a bat house that fits the needs of the bat.
I believe cedar is the best wood as it weathers well and last several years in the weather. The problem is that it is hard to find plywood cedar. You can buy untreated cedar fence boards that work well but does require more work.
Untreated pine is also available but does not last as long in the weather as cedar. Whatever you choose to use, it is important to use untreated and a wood that can withstand the weather.
I am including links to reputable sites with bat house plans.
- Bat House Builder's Handbook
- Bat Conservation International
Assembly
Do not use mesh anywhere in the bat house. The mesh can come loose and trap bats, including pups, inside the box. It is best to manually make the grooves on the inside of the bat house for the bats to grip. The grooves do not have to be fancy. Scratching the surface up with a sharp utility knife will work. They do not have to be deep. Just rough.
I would use screws instead of nails to assemble the box. The reason is that the screws make it easier when you need to do repairs. You can back out the screws but pulling out nails can cause more damage to the box. Use a little wood putty to cover screw heads with a lite sanding before you paint.
Use nontoxic caulking to close up any seams to prevent rain from entering the box so it remains dry.
It is important to paint the bat house. It helps the wood last longer and it also plays a vital role in the internal box temperature. Darker colors absorb heat which will make the box warmer. Lighter colors reflect the heat which makes cooler boxes. So the further north you live, the darker you want the box.
- Zone 1 (blue areas) less than 85˚ = Black paint color
- Zone 2 (green areas) 85˚-95˚ = Dark gray paint color
- Zone 3 (yellow areas) 95˚-100˚ = Medium gray paint color
- Zone 4 (light pink areas) 100˚+ = Light gray paint color
MAP OF US
Now that your box is assembled, it is time to mount it on a pole or building.
More info on bat houses from Bat Conservation International
VIDEO 2