Here's my update on the bat house project. Folks have sent coments asking for an update - don't have any bats quite yet, bu their house is installed and open for business. Thanks to Creator's Studio, I had plenty of good paint, so I lavished several coats to make sure this bat house has a long life.
Following the excellent (and free) shop plans from http://www.floridabats.org, I dug through the lumber at Home Depot to find 1x boards of cedar, brought them home, and cut it into the various lengths called for in the plans. I had some ¾” OSB left over from another project, so I saved about $15 on materials; I made the two baffles out of OSB instead of the marine-grade plywood the plans specified. I would normally be concerned about how OSB deteriorates when wet, but since the baffles are inside a rain-tight box and I gave them three heavy coats of paint before assembly I figure they will do just fine.
The assembly instructions were clear. After fastening mesh material (to give the bats something to climb on/cling to, everything went together using construction screws (with star pattern drive.) All joints received a coating of waterproof carpentry glue. When the glue dried, all corners received a generous bead of silicone caulk; plan said to do one or the other, so I did both to ensure a dry interior.
The bat house received several coats of paint even though cedar weathers quite well. The paint is a top-of-the-line indoor/outdoor tintable primer by Zinsser which spread nicely and took extra coats easily. The bat house is mounted on a brace made of pressure treated 2x4 beams; the 2x4 brace is secured to a pressure treated 4x4. I departed from the plans as regarding mounting instructions because I wanted to provide extra strength against severe winds and I wanted to be able to take the box down for cleaning and repairs. As it turned out, my choice of mounting method also made it a lot easier to install.
I used what is known as a “French cleat” on the back of the bat house that mates with an opposing cleat atop the mounting brace. A French cleat will not only hold an enormous weight, it will prevent sagging or loosening over time. Two construction screws secure the bottom of the bat house to the lower cross member of the mounting brace, so it is firmly in place.
Thanks to the generous supply of paint, I coated the mounting brace and the 4x4 – pressure treated wood benefits from this extra protective coating. I recommend painting the supports as well as the box as it looks so much nicer when installed.
Firmly installed along the back fence, our bat house is ready for occupancy. The on-line bat experts instruct that new bat houses should be in place during the winter months as bats go looking for new lodging in the spring when their habitat gets crowded. It is hard to see, but technically, this is winter in Florida, so the timing is perfect. All the other variables such as height above ground, southerly exposure, paint color, etc. have been followed carefully, so we should get bats this spring.
The finished bat house slipped into place – the French cleat made it very easy and very stable. I drove two more construction screws through flat washers at each corner of the landing pad to complete the installation. Now we watch and wait . . . .
I figure about $75 in materials, but I had some things in my shop like screws, scrap lumber, and caulk, so I managed a savings. Creator's Studio awarded me lots of paint, so that was another thing I didn't have to get. The 4x4 post would have been another expense, but I had to make hurricane repairs and decided to put in an extra tall fence post - I have thought about installing a bat house for some time and knew I'd need it high off the ground. Some use a 2" galvanized pipe to support their bat house (and secure it with U-bolts, but I opted for an all-wood construction so it would be part of my fence.
In addition to putting a dent in the local mosquito population, I hope to use the guano that will accumulate underneath the bat house. I've read that watering plants with a "tea" made from soaking bat guano makes an excellent (and free) natural fertilizer. I guess I have indeed gone batty!