Scott’s Bat House Page - Medium Bat House Plans

2 Houses - 3 Chambers Each

Updated For 2008 Season

Chamber dimensions: 14” wide x 30.5” tall

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These plans are NOT for commercial use without permission.

I'm trying to raise funds for PV solar panels for my house, please help me out by paying for the most useful part (the cutting diagram). Notice the cutting diagram is not shown anywhere on my webpage. You must pay first to get it.

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Please Read the Safety and Liability Statement Before You Begin Working.

The cutting diagram is of a single sheet of 3/8” ACX, BCX, or T1-11 exterior plywood (CDX is ok) and 2 untreated 8ft 2x4’s (1.5” x 3.5” x 8’). See the imbedded pictures for how it should look completed. See my bat house homepage and Bats Magazine v11n1-3 for more information.

Free Bat house plans, Free bat house design, bat habitat, enhance wildlife habitat, free wood working projects, Free Bat house plans, Free bat house design, bat habitat, enhance wildlife habitat, free wood working projects,

Materials List: Tools required:

2 – 2”x4”x8’ untreated cedar, fir, or pine Table Saw or Circular Saw

1 sheet 3/8” plywood (ACX, BCX, or T1-11 grade) Tape measure

1 lb box of screws - 2 1/2" exterior grade Power drill with bit for screws and 1/2" spade bit

1 lb box of 6d nails – outdoor Caulking gun

1 tube caulk – exterior paintable T-Square or straight edge

1 sheet of sandpaper medium-course grit Paint brush (4”)

1 quart exterior latex primer Hammer

1 quart exterior latex paint (see color info below) Safety goggles

1 can black spray paint Ear protection

plastic mesh (optional) Staple gun (optional)

1/4" exterior staples (optional) Dado blade (optional, but helpful)

PLUS any material for installing house (will vary).

Instructions:

1) Cut out the pieces from the plywood as shown in the cutting diagram that you have to buy (use ACX, BCX or T1-11 for better longevity then CDX). The measurements with “~” should be the last cuts. Note that slats 1.B part 1 and 1.B part 2 should be stacked together to make one complete slat similar to the others. The bats won’t care that it is more then one piece and no one can see it.

2) You have two options for the sides and ceilings: a) If you have a table saw, rip the 2x4’s to 3 inches wide (preferred), b) If not just continue.

NOTE: Instructions from here on are for one house, repeat each step for the second house.

3) Groove the worst looking side of the 2x4 the long way with 3/4" spaces (15/16” spaces if you didn’t rip the boards to 3”) and 3/8” wide by 1/2” deep grooves to fit the slats (a total of 2 grooves each house). See the picture to the right below. A table saw with dado blade is very helpful, but you can do it with a router or a skill saw and a chisel. You will also need to dato out a place in the sides for the ceiling to fit (1 1/2” wide, across the short way, just below the angle for the roof.) The picture shows that too.

4) Check to see that the plywood actually fits in to the groove without too much trouble, if it doesn’t then make the groove a little wider. This will save you a lot of time later. It should be snug, but not so snug that you can’t get it in.

5) Make the cross-cuts on the 2x4’s as shown in the diagram.

6) You should lightly groove or scratch (1/32” to 1/16” deep) the plywood slats on both sides as well as the insides of the back and the front at about 1/2” horizontal intervals so the bats can hang on better. Use a skill saw or a utility knife. Groove the landing pad too (the lowest 6 “ of the inside of the back). Alternately you can staple on 1/4 or 1/8 in plastic mesh instead of grooving it, but make sure your staples don’t go through the plywood.

7) Slide the ceiling into the wide grooves in the side so the narrow grooves in the ceiling all line up with the narrow grooves on the sides. Screw the ceiling to the sides.

8) Screw the back to the sides and ceiling with 4 to 6 – 2 1/2” exterior grade screws making sure you don’t block the grooves with the screws. (Note: the plywood won’t be flush with the outer edge of the sides.)

9) CAULK the joints between the back and the sides (50 yr exterior latex or silicone paintable caulk). Caulking is very important to retain heat.

10) Slide in the slats and tack them in with 1 or 2 nails each (they should fit pretty snugly so you might have to tap them in with a hammer.) Here is what they looked like after I installed and painted them.

11) Put a bead of caulk along the top diagonal face of the sides.

12) Screw on the roof

13) Put a bead of caulk along the front face of the sides

14) Screw on the front (make sure it is snug with the roof)

15) See the note (below) about venting – now is a good time to put the vents in if you are going to.

16) If the slat boards warp a lot you might want to put 3/4 in. spacers in each crevice and screw them in place with long screws from the front and back (Hint: stack 2 small scrap pieces of the 3/8 in plywood for a spacer)

17) Caulk around the outside of the roof, front, and back joints.

18) Allow all caulk to dry

19) Sand, prime, and paint the whole outside with at least two coats of BLACK or appropriate color paint (I used brown for a house in southern Oklahoma, because summers get pretty warm there)

20) Paint the bottom of the slats and up into the chambers a little way with black spray paint. A light coat will do. The bats like the dark.

Don’t miss this additional valuable resource from BCI:

The Bat House Builder's Handbook – Second edition - 2005

Important Info to consider:

For best results make multiple houses with this design or others. For more information on where to put your bat house, what color to paint, etc. see the BCI bat house criteria page.

Color:

As I mentioned before, you should probably paint the whole outside of the house with at least a couple coats of black exterior paint in most of northern North America to get it warm enough for the bats. Check the bat house criteria page for the appropriate color for your region. Lighter colors for warmer regions. If you have a dark colored house and see bats leaving during the heat of the day you should put up another house nearby that is painted white.

Venting:

If you live in more southern latitudes and are worried about overheating (usually the problem is under-heating) you should drill 1/2” vent holes in the lower parts of the sides of a few of the chambers. You might have also seen other plans with a 1/2” opening all the way across the front about 6”-10” from the bottom, which will keep at least a portion of the house cooler. Go ahead and do that if you live in a warm area. You can cut the vents in before you put the house together or after.

Placement:

Face the front of the house towards the S to SE to take best advantage of the solar heating (6+ hrs of sunlight is best, even more in northern latitudes). Put the house up as high as you reasonably can – the bottom should be 12 ft (3.5 m) high minimum but as high as 25 ft (8m) or more should be great. You can mount it above a building, on a building (brick or wood NOT metal) or put it up on a tall pole or poles (this could be hard to do because it will be heavy, so get help). I don’t recommend putting it on a tree because it will most likely be too shaded, but if you have a good sunny spot on a tall dead tree, go for it. See these links for info from BCI on putting bat houses on poles: BHR8n2-3 and BHR5n2-4.

Experiments to Try:

Research about bats’ preferences is still ongoing so experiments are needed. Make two or more houses of the same starting design and alter only one factor about each of them. This allows you to conclude that the single factor that you changed is what caused the difference at your location and is part of a good scientific experimental design. If you make only one house go with the standard model first (with the correct color and venting for your region). Some factors to experiment with on your second or third house are (in the order of my interest in trying):

Heat Sinks –(e.g. concrete, bricks, soil, bottled water, etc) should help prevent overheating during the day by absorbing the suns heat and overcooling at night by releasing the heat stored from the day. Try filling the attic and/or possibly all or part of the center chamber of my models with concrete or whatever you have that might work. Keep in mind that it will make the house considerably heavier and that you will need to take measures to keep the material in the center chamber (if you decide to put it there) from falling out and hitting you in the head. Also in colder regions or in houses that don’t get enough sun the heat sink might prevent the house from warming enough, which would be a problem.

Insulation - (e.g. spray foam or Styrofoam) Unlike heat sinks, which store heat, insulation limits the amount of heat (or cold) entering and leaving a bat house. There is a subtle difference in the mechanics but the end result is similar. Try insulating the attic and maybe also the top 10” or so of a few (non adjacent) chambers. Just as with a heat sink too much of it can keep your house too cool, which is bad.

Venting – Vary the amount of venting on your second bat house. Either add more vents or take them away as you see fit depending on your climate. NOTE: In warmer climates make sure to include venting on most of your houses.

Color – paint one darker or lighter than what is recommended. NOTE: Make sure the majority of your houses are the recommended color for your region.

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Safety and Liability Statement:

Please read the plans carefully and completely before beginning and use the proper safety equipment, especially safety glasses and ear protection, when working with any tools. I have successfully built a bat house with these plans, but I am not responsible for any errors it may contain. Use the plans at your own risk. Let me know if you find any errors and I will fix them..

Good Luck attracting bats!! Let me know how it turns out!!

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Last update 1/26/2008, SMH