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The Bat House: a Green, Energy Efficient Insect Repellant

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It's summer, and you know what that means.......an abundance of nature's flying vermin--mosquitos! 

Instead of buying a bug zapper, try building a GREEN, ENERGY EFFICIENT alternative: a bat house!

Bats are mother nature's insecticide, and a single brown bat can eat up to 1,000 mosquitos an hour! (http://www.eparks.org/wildlife_protection/wildlife_facts/bats/bat_house.asp). Additionally, bats are an essential part of a healthy ecosystem, and their populations have diminished in recent times due to deforestation and loss of habitat. Lastly, bats are just cool. 

Bat houses come in a myriad of shapes and sizes, but I decided to build the most simple version I could find. This is a Single Chamber bat house, and can hold up to 50 bats. This design was based off of the plans from eparks.org (link above), and I need to give credit to good friends of mine, the Warren clan for inspiring me to build one, and for tips and advice.


Step 1: Supplies and Materials

Picture of Supplies and Materials
IMG_0795.jpg
This is a fairly simple build, but you will need some hardware: 

The size of your bat house can vary, depending on the amount of wood you have available. Use these measurements as an approximation if your supplies are lacking. 
  • 1/2'' or 3/4'' outdoor grade plywood (or whatever you have)
    • 26.5'' x 24'' -- the backboard
    • 16.5'' x 24''
    • 5'' x 24'' 
    • 1'' x 21.5'' (two)
    • 1'' x 22'' 
  • 1'' screws
  • exterior (water based!) staining or sealant 
  • caulk
  • black spray paint and tape (optional-for decaling)
  • shingles, galvanized metal sheet, or left over wood for a roof (optional)
  • saw
    • miter saw
    • table saw
    • hand saw (if don't have a miter saw or table saw)

 
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How do you encourage them to come hangout?

sconner12 years ago
Good Idea. We have an area of standing water near out home. This woild be good to help fight mosquitos.
I know bats can get into some tight spaces, but do you think 1/2 to 3/4" is wide enough for them to nest?
I've seen other designs that look like there is about 1-1/2" to 2-1/2" inside.
I discussed it a few years ago with a biologist and it (the opening size) can depend on the type of bats that are common to the area.

If I remember correctly for instance in the Memphis, TN area Mexican Free Tail and Small Brown Bats are common and he suggested 1/2 to 3/4 inch openings were best.

I designed a few years ago a multi-layered bat house that incorporated different size openings to give the best advantage for occupancy.

slylee (author)  sconner12 years ago
Well according to batcon.org, the space should be 1''. You don't want it too wide because they get cold easily, and you don't want heat to escape.
Like some of the other said stay away from treated wood since it off gases. Some consideration may need to be given to the area of the country it's to be mounted. If's a real cold climate a darker color may be needed just as a hot area may need a lighter color.

You can go with a latex house paint but leave the interior plain. Check with your local extension agent or someone in the area familiar with bats to determine if a color is needed.

I suggest if possible let the wood age naturally. Bats often nest in dead trees or areas under the flaps of bark.

The grooves are great and it has a good size and landing area. The depth is important since the bats need to be able to stay away from predators.

I would suggest adding another layer on the interior. It should be open below the roof allowing the bats to move across the top of the divider. This gives them the ability to move from front to back depending on the temperature. They don't need much space between the layers since they like tight places.

The open area at the top below the roof is also beneficial for raising young.

This location has some good information. http://www.maberrybat.com/index.php?module=Pagesetter&func=viewpub&tid=5&pid=2
slylee (author)  Dickerson8882 years ago
I haven't seen nor heard from any biologist I talked to of any proof about the harm of using synthetic wood. You don't want to add another opening below the roof because it would let heat out. This is the same reason why you should place the bat house in the sun. They get cold easily.
Synthetic wood might be OK as long as it doesn't off gas as it ages or heats up.

I'm referring to an open area below the existing roof.

The box is slightly thicker with center dividers or additional panels. The panels would not go all the way to the top allowing an open area below the existing roof. This allows an area just below the roof on the interior where the bats can raise young.

This also allows the bats to move across the top of the panels front to back or back to front depending on the temperature.
mikolynn2 years ago
AAAAAHHHH!!!!! STOP AND CORRECT IT! you do a BIG ERROR! If you build it with this kind of plywood or other synthetic wood, you kill the baby bats...
When the baby bats are there, is a great temperature inside the house and with this heat, the synthetic glues and polymers used to build up this "wood" generate gas who kill the bats. They are really sensitives to synthetic materials... The best what you can do with this house, is to burn it up, and build new one with natural, untreated wood. The unique material what you can use as a wood conservative is some vegetable (NOT MINERAL) oil. And also the same for the paint and sealants!
slylee (author)  mikolynn2 years ago
So I've been researching online and talking with local biologists at our University, and I found no evidence that plywood or treated wood is bad to use in a bat house. Furthermore, bats take up residence in attics and awnings all the time, and those places not only have synthetic wood, but also fireproofing materials. So I think it is perfectly ok to use plywood and synthetic wood to built a bat house. I also know of many people who built their bathhouses with plywood and each summer they have 50+bats living in each house.
FYI Burning treated wood is an extremely bad idea. I don't know about the accuracy of your statement on bat health but this one is fairly common knowledge.
;) thats right, maybe the best is to build up another think, maybe a toy parking? a puppets theather? a magic mistery box?
slylee (author)  mikolynn2 years ago
Could you provide links or references for this? I'm not a bat expert, but I didn't read anything about this in any of the conservation websites for bat houses.
mikolynn slylee2 years ago
I know it from time along and read it somewhere arround... Loking for something I found this manual for how to build up nest-houses is in spanish, and they say the same, http://www.xoriguer.org/ftpxoriguer/volcam_2007/Manual_cajas_nido_VOLCAM_2007.pdf But only talk about the "preferences" of the bats with the wood or paints... Before, when I read about it I read something about the steams generated inside the house...
I continue loking for it. And If I find, I will inform... ;)
IF you seal the interior, use a WATER BASED sealant only. The residual fumes will keep the bats away until the fumes are completely gone.

There is no real need for interior sealing.

Exterior sealant should also be water-based, same reason.

I built 3 two years ago, one I did not seal, the other 2 I sprayed.

Still waiting on bats to move into the 2 I sealed.

Good Instructable and good design. Thanks for a couple of good tips!
slylee (author)  GrumpyOldGoat2 years ago
Thanks for the reminder. Did any bats move into your houses?
There are signs of droppings around the unsealed house, but not all the time.

There are no street lights around to attract huge numbers of bugs, and I seldom see bats in the area, so that may be one reason.
hehinckley2 years ago
My husband built a bat house and placed it at the north peak of our house. There is an added on porch beneath it, so he could stand on the roof and put up the bat house. Unfortunately, the bats' guano falls out of the house onto the roof and piles up. It looks horrible from a distance. So my husband has to spray it down occasionally. Another unfortunate....the guano has stained the shingles under the bat house.
Also, I would not attach it to the house wall anywhere else. the bats poop as they fly into the house, and there would be bat guano on the wall of the house for several square feet under the bat house.
It definitely should go on a pole away from the house.
Nice design. My husband built his several chambers deep, and it works well, even though it is on the northside of the house.
Another word of warning, if you build a bat house to attract bats to your area, they may also take up residence in your eaves, if there is any crack in them. Also they lived in our wood stove chimneys, so you would need to put a small mesh wire over the top of your chimney.
slylee (author)  hehinckley2 years ago
Thanks for the tip. Definitely don't want bat poo all over my house.
danny3xd2 years ago
Love it! Always wanted a bat house. Building a work shop in the back yard. Gonna cover it with bat and bird housing. Birds clear the yard of bugs by day and bats by night. Using your design and scrap to build a big one. Thanks!

Just asking here, might it be better to leave the inside bare? The reason I ask is am worried that some chemicals used for finishing wood could hurt our lil skeeter eating friends.
slylee (author)  danny3xd2 years ago
Thanks. Actually I did leave the inside of my bat house bare, despite all the designs and conservation sites suggesting coating the inside. I suppose if it is a water based sealant it would be ok...
Opps, just saw your post GOG.
hbannink2 years ago
Well done Like your attitude about nature and the bat house is nifty too
slylee (author)  hbannink2 years ago
Thanks hbannink! I like nature and try my best to preserve/respect it.
earthlings2 years ago
Have any bats taken advantage of your lovely home?
slylee (author)  earthlings2 years ago
Not quite yet. I think I may need to move it to a pole. Most of the conservation resources suggested it was the best location.
alanemartin2 years ago
Nice job. batcon.org (no, I'm not affiliated) has some good tips on color selection for the exterior depending on where you live (to help regulate the interior temp). You could easily leave the interior untreated...the fewer chemicals near the bats the better, I'd think.
slylee (author)  alanemartin2 years ago
Cool. yeah I actually didn't coat the interior of my bathouse, even though some references recommended it.
mjlush2 years ago
Think carefully were you put this up. Unlike bird-boxes, bat roosts are occupied all year round. So you can't simply take it down in winter if you want to do any work on the building/tree its attached to or get tired of the accumulation of guano

If you live in the UK a criminal offence to damage or disturb a bat roost
mikolynn2 years ago
Ah, and for the place of the bat cave house is good to place it at a minimum of 100feets of the nearest house. They prefeer a quiet life...
I haven't looked it up in a long time but there are specific places that are best. If I remember right it should not be in direct sunlight and on the west facing side of the pole or structure. I love the bat logo too!
slylee (author)  mr.incredible2 years ago
Hey good point! I do remember they should Ideally be facing southeast or so, so they can catch some sun during the morning to warm their little bodies up.
badwooki2 years ago
try to do a search I have heard there are companies that will ship bats (try for bats native to your area ) and then you may have your flying resident rodents... good luck
I try to help ... but also nice stuctable
slylee (author)  badwooki2 years ago
wow that is interesting. I think that would be a good back up plan. I know we have some bats around here, I think I just need to provide the optimal habitat for them.
wnordmann2 years ago
Have any bats moved in?
slylee (author)  wnordmann2 years ago
Not as far as I can tell. I think I may move it to a post or on the side of my house. NWF advises that this is the prime location for bats to locate the houses.
Great design - love the finishing touch with the logo!
slylee (author)  jessyratfink2 years ago
why thank you!