If you have kids, you probably already know how much they enjoy building things, especially with their mom or dad. Some folks build things out of popsickle sticks, others build bird houses. But what could be cooler than building a bat house?
Bats are greatly misunderstood creatures. They do not feast on human blood nor consort with vampires. They are voracious eaters, however, but their main food source consists of insects, and yes, that includes those pesky mosquitos that do feast on human blood. A single bat will eat its own weight in insects in a single night. So build a bat house and invite a colony of bats into your neighborhood.
Below you will find a simple plan for building a quality bat house which can be completed over a weekend and built with about $30 to $50 of materials. This plan is somewhat general. I've always considered a plan to be a rough guideline, so take the measurements below as such. I've included general dimensions and a lot of photos.
1 2x8, 8 feet long
2 8 inch pieces of 1x2 furring strips
2 or 3 sheets of 1/4 inch plywood
1 sheet of 1/2 inch plywood
1 2x4 about 5 feet long
1 inch brass wood screws
some type of dark stain
marine spar varnish (optional)
Cut the 2x8 into two equal length pieces, about 48 inch long.
Cut 6, 1/4 inch grooves lengthwise into the 2x8's. These should be spaced 3/4 inches apart. I used my table saw for this. Set the blade about a half inch high and the guide to 3/4 inch and run the piece through to make a 1/8 inch groove 3/4 of an inch from one edge. Then slide the guide over 1/8 of an inch for a second pass which will widen the groove to 1/4 inch. Next, adjust the guide 3/4 of an inch wider repeat for the second groove, etc.
Next, cut a 45 degree angle on each end of the 2x8 as shown in the photo below. Make sure you cut the 45's such that when you sandwich the 2x8's together, the grooves face each other as shown.
Cut a piece of 1/2 inch plywood 2 feet wide and about 49 inches long. The length should be about 1 inch longer than your 2x8's. This piece will become the back of the bat house. Use a circular saw set at a 45 degree angle to make the cut. The long edge of the 2x8's should line up flush with the 45 degree cuts to make a smooth transition from the plywood to the 2x8's.
Predrill about 5 holes along the edge of the plywood to accept your brass wood screws which will hold the plywood and the 2x8's together. Before attaching permanently, I recommend running a bead of adhesive caulk along the edge of the 2x8 for a stronger and more weather resistant joint as shown in the above photo. Go ahead and attach the plywood back to the 2x8 sides.
Cut a 2x4 to run the length of the middle of the back of the bat houuse and use 1-1/2 inch lag screws to hold it in place. You will use this board to hang your bat house, so leave enough sticking out at the top and bottom to be able to drill a hole and insert a heavy bolt or screw.
Cut two furring strips wide enough to span the 2x8 and screw them into place with brass screws as shown below, one on each side. This end will be the bottom of the bat house when it is hung vertically. These strips will hold the 1/4 inch plywood slats in place and keep them from falling out.
Next, cut your 1/4 inch plywood slats to slide into your grooves. Each one will be a different length. Measure the length from the furring strip to about two inches below the top 45 degree edge of the 2x8 side piecees. Slide the slats in place. The bats will actually climb up in between the slats which is where they will sleep during the day. They like the tight spaces and the like it very warm
Cut a piece of 1/2 inch plywood for the front of the bat house. Like with the back, use a circular saw and make the cut at a 45 degree angle for a smooth transition from the edge of the 2x8 sides to the plywood front.
Cut a piece of 1/2 inch plywood for the top of the bat house. The edge that joins with the front should be cut at a 45 degree angle and overlap the front. The top edge should be cut at a 45 degree angle and meet flat with the 2x4 mounting rail. Predrill the holes for the screws and use adhesive caulk for a stronger, more weather resistant joint. Make sure all slats are in place and then attach the front and top.
Drill a 1/2 inch hole near the top of each side (you can see this in the photo above). This will allow a little bit of air circulation for the bats. Don't make it too big, bats like it hot.
Use a belt sander and sand the whole thing smooth. Unfortuneatly, I don't seem to have a photo of this stage, but the bat house looked really nice at this point :-).
We are now ready to finish it by sealing it from the weather. I used two coats of a dark brown transparent stain, followed by three coats of marine spar varnish. Below are photos after all coats of finish were applied.
One final step (no photo available). Staple a fine mesh screen to the bottom area so that the bats have something to grab onto when they land on the bottom landing. This is importantant, otherwise the bats may have trouble climbing up into the house.