The sides should be smooth to avoid abrasions of the nose. Wire cages do not retain heat and can result in foot and nose trauma. Cages should be simple in design to facilitate cleaning. Cages made of wood must be sealed with polyurethane or a similar waterproofing agent and joints caulked to allow cleaning and disinfection. Fresh polyurethane must be allowed to dry several days and the cage thoroughly aired out prior to placing a reptile in the cage or toxicity may result.
Lizards require large cages to accommodate their active behavior.
A 40-gallon terrarium with a screen lid will accommodate a young iguana. Since iguanas grow so fast, however, the larger the terrarium you can buy, the better. As the iguana grows and becomes longer than 3 feet, you will need something custom built. In warmer areas of the United States, large outdoor walk-in enclosures provide a good habitat. The substrate is what lines the bottom of the cage.