- Interior dimensions should be about 5 inches square.
- The hole should be 1 1/2 inches or less to prevent larger birds from stealing the nest site.
- The hole should be 5-8 inches off the floor of the house
Other than that I have read that you shouldn't paint the house. However, I have also seen dozens of advertisements for decoratively painted houses. Right now I have a white house hanging in my back yard as an experiment to see if any birds will nest there.