First of all, I used this handout from Wild About Gardens as the guide for building the bat houses. One caveat is the measurements are in metric. I decided not to convert them and just grabbed an old fashioned meter stick and ruler. You will want to print off the handout to get your supply list and cut list.
While I bought all the supplies at once, I didn't make all the houses at once. I wanted to cut and make one sample one before I started cutting boards for the other boxes. Couple things about the supplies. You will want to make sure the wood is not treated. Treated wood has all sorts of chemicals that wouldn't be good for bats. Also, before you search the entire store, the rubber flaps you need for the hinge are in the plumbing section. You could use a nail gun if you're doing this for personal use. Otherwise you will want to pick up some nails. You will see I used huge roofing nails which aren't the ideal type of nails. This was a conscious decision since the large head on the nails would be easier for the young girls to hit. Also, I did bring wood glue, some small bowls and a bunch of q-tips and had the girls glue each piece before nailing it together.
I made all the cuts for the first sample box. If you're making extras for little kids to build, you will want to take a moment between attaching all the different pieces to measure and record where the nails are going in. That way you can predrill all the holes on the other bat houses. If you have older girls, you can skip this step because they don't need to be predrilled.
Also, if you plan on painting the outside of the box, it might be easier to paint the pieces prior to building the box. I painted all the pieces that would be facing out but left the inside a natural wood. I used black since the color adds extra heat.
First step: Attach the front piece to the side pieces. The front piece will sit inside the side pieces. Please see the handout or pictures for examples. The side pieces and front piece will slant towards the front.
Second step: Attach the bottom piece to the bat house. This piece will also be set inside the side pieces. It will sit flush with the front piece leaving a 10 cm gap in the back for the bats to enter the bat house.
Third step: You need to rough up the back piece. I did this by using a sharp nail and pressure. Then attach the bat house to the back piece.
Last step: Attach the rubber flap to the top piece. The angled portion will go towards the back. Then attach the top to the back piece.
Ta-Da! You have a wonderful bat box to make the local insect eaters happy. Mount the bat box at least 10 feet from the ground in a sun location facing east or south. Bats are happiest when there's at least 6-8 hours of direct sunlight.