The floor of both pine and oak boxes is inset slightly and the bottom of the walls tapered. This helps the rain drip from the box rather than being absorbed into the end grain of the wood. It also helps to increase the life of the box.
To help deter predators a ledge is incorporated inside the box. This prevents cats and the like from scooping the eggs or the chicks from the nest.
The entrance to the box is covered with a metal plate. This prevents squirrels and woodpeckers from enlarging the hole to gain access to the box.
Finally, to ensure that rain does not enter the box when hung flat against a tree or wall, the box is designed to be simply supported away from the wall. The box is easily hung by means of a top hook and secured by a bottom screw. This ensures both easy hanging and removal yet remains sturdily fixed in position.