Build a box that will stay dry and warm. Place the roof of a birdhouse at a slight angle and extend it over the sides and front of the box. In this way, the roof will shed rain or snow and protect the entrance hole and sides from dripping water. Drill four, 1ǚ_inch holes in the floor to provide drainage if water seeps in. The sides of a nest box should extend down beyond the floor so water won't leak in.
Avoid bird houses made of metal. Metal houses will become miniature ovens in summer heat, and reflective metals are highly visible to predators. The house can have metal guards or trim over a different material, however, such as a metal cover to fix an entrance hole to the proper size if needed. Healthy Houses: Bird houses can become crowded as nestlings grow, giving diseases and mites greater opportunities to spread to young birds. A safe bird house is one that takes into account the health of the birds.