Make sure theres no less than 12' from the very bottom to the ground. Bats glide when taking off and need at least 12' to get the motor running. I've never put one on the side of a building. I have however built three on phone poles in the wide open and all three are full of bats. Boboro, I think you wouldn't like the smell that will be coming from that box if you do get them to inhabit it. They will also pee all down the side of the building, and it stinks.