Excellent report, Loretta. Thanks.
During that waiting period for tenants, did you have any issues with wasps trying to build nests, or similar? Also, now that you do have no vacancy, do you see any probs with critters trying to get a bat snack?...or, are the slat openings too small for access?
I've never had any problem with wasps or other insects trying to occupy the bat house, even when it was empty but maybe it's because it's made out of cedar. I do get plenty of mud-daubers on the ceiling of my porches! I'm going to paint the porch ceilings blue like the sky, I'm told it discourages wasps and other insects.
No critters have tried snacking on the bats, I don't think anything could get up there and there is only one opening, no slats, it's basically just a box. The box has a peaked roof and a bat symbol (think batman) wood burned (stamped) on the eave. On the inside of the box the back wood is scored with a saw to help them hold on. Very easy to make but I bought mine.
Here are some old pictures taken with a cell phone.



If you've seen bats flying around at night be patient, they will find the house and occupy it. When I first put my bat house up I never noticed any bats at all and I live in the country. Now it's easy to spot a bat on any night.