Ideal buildings for barn owl nestboxes are at least 4 metres 13ft high with an opening or hole at least 3 metres 10ft above ground level which overlooks open countryside where the nestbox can be positioned 3 metres 10 ft above the ground. Purpose to construct and install a fully functioning barn owl nest box that can be used for nesting broods why build a barn owl box barn owls are one of the most widespread owl species in the world but in many parts of their range across the united states populations have been declining because of habitat loss. 1 appropriate size too many barn owl box designs create a nest box that might be only 18 deep while this size can attract a breeding pair keep in mind that barn owls produce an extraordinary number of young seven is quite common