Often, people want to be as near the nest as possible to be able to hear and see their resident birds. Since barn owls are highly tolerant of human activity, the answer is that barn owls will often nest very near a house. We have photos of occupied boxes as little as thirty feet away from the house. During breeding season the birds can be very vocal at night, and when the chicks are nearly grown, they spend a lot of time near the entrance, begging for food. So, perhaps a distance of fifty feet minimum is a good compromise.