Per instructions from Bat Conservation International, we installed a treated post at least 10 feet tall. Ours ended up with about 3 feet in the ground and 12 feet out.
Progressive back-filling and tamping while watching for plumb using a post leveler (strap-on plastic level) is essential to getting a good post installation. Our post was scrounged and had a bow on one end so we made a wide hole and put the bowed end under ground.
Using opposing ladders and installers provides some additional safety measures.
A-OK and ready for inhabitants, rent-free!
In addition to attracting more bats to our orchard and nursery area, we gain a cool vertical feature.
This shot shows the second bat box opposing the one shown above. One is wider than the other so we placed the wider one facing north so that the overlap would receive some sunlight from the south and help keep it warm.
Ready for your own bat house? If so, start here.