Many factors come into play when deciding how to create your aviary, depending on which part of the country you live in. If you build indoor aviaries, you must consider that diseases spread more easily inside than outside. Cleanup is more labor intensive inside, and ventilation is very important, as well as lighting. On the upside, you have control over the weather conditions and are more protected against theft. Disease from wild birds and predation from some of the larger wild animals that may be indigenous to your area are eliminated.
Outdoor aviaries have disadvantages to consider when in the planning stages.
Preventing escape is a priority when designing the cages or aviary, as well as preventing predators from the outside gaining access to your birds. You are much more vulnerable to theft and weather conditions. Of course the advantages make it worth the effort to build outside aviaries. The ultraviolet rays from the sun are a wonderful sanitizer when it comes to bacteria, virus, fungus and many of the protozoa. The sun also allows natural vitamin D3 to be utilized.