Some manufacturers use copper or other metals on the outside of houses for durability or decorative purposes. This is not a good idea. These metal parts can get very hot in the summer sun, especially in the deep south. There is also a bluebird house on the market that does not have a roof. The location of the house is very important.
Bluebirds prefer open grassy areas with enough trees or wires to provide perches.
Pastures, open woods, and orchards make good locations. A golf course is a very good example of bluebird habitat. Avoid thick woods, large open areas with no trees, or open areas with very tall grass. The usual distance between houses is about 200 feet. Bluebirds are territorial and will usually not allow another pair to nest in the approximately 2 acres they claim as their own.