1) Size - Since iguanas can grow up to 6 feet in length, do I need an entire room to house them? Well the short answer to that is no but the enclosure still needs to be big enough to fulfill your iguana's needs.
The ideal cage will not limit the size of your iguana and the activities that take place inside the cage will ultimately determine the size.
Your iguana should not feel cramped and should be able to move around freely and easily.
Iguanas enjoy climbing up onto the branches of trees and they also like to jump and swim from time to time.
Therefore adequate space for these activities must be provided.
Generally when the iguana reaches full size it may be necessary to move it to a bigger cage which should be prepared for in advance.
2) Temperature - Since Iguanas are cold blooded animals, they need to constantly regulate their body temperatures.
This means that the environment in which they are placed in must be warm enough to fulfill their heating needs.
There needs to be a supply of different temperatures in the cage so that the iguana can move from spot to spot in order to regulate its body temperature.
Cages that are built outside must ensure that there are sunny and shady spots available for the iguana.
The exposure to the sunlight, allows for iguanas to receive enough heat, which is required to regulate their body temperatures.
At night, however, the iguana must be brought inside because they can die from the cold.
Also there should be a source of heat without light inside for night time purposes, to ensure sufficient warmth for your pet.
3) Humidity - In order to live comfortably, iguanas need a high level of humidity.
They tend to get dehydrated easily because they don't drink enough water.
In native habitats, the high humidity prevents dehydration which is why you should try to replicate their habitat as best as you can.
If you do not provide enough humidity for your iguana, it will shorten its life span.
Humidity also assists in loosening the skin which makes shedding easier.
The ideal humidity should be around 65 to 75 percent in order to ensure maximum development and health.
4) Lighting - Iguanas require a source of UVA and UVB light in order to assist in producing vitamin D3, which ultimately helps in consuming calcium.
Obviously the best source of light is the sun, but the glass or plastic coverings on iguana cages tend to filter out any of the UV rays that are needed.
Therefore, you must ensure that your iguana has plenty time to bask in direct sunlight without any blockage.
Without enough light, iguanas can be prone to developing The Metabolic Bone Disease which is a common cause of death in iguanas that live in captivity.
Also make sure that there is an artificial source of UV light in the cage in order to make up for days when sunlight is not available or sufficient.
So, there you have it.
Follow these simple guidelines and you will be well on your way to building the perfect iguana cage.