You may be wondering how to build a chicken coop that will not only keep your chickens locked up and protected from bad weather and predators yet receive the proper ventilation it requires. If so, then you already understand the importance of draft free air movement from within the coop. Chickens, much like humans, need fresh air and oxygen. The same goes for the removal of unwanted excessive moisture and carbon dioxide. A chicken coop with ample air movement and proper ventilation will help remove the ammonia build up and dampness that may grow inside its walls.