Houses can be erected from 10-15 ft above the ground. No vines, shrubs, fences or wires should be near the martin houses. These only contribute to the deaths of colonies of martins. Martins houses can be placed closed to one another. There are many PM house plans available through DNR, other state conservation departments and birdhouse books, but many, if not all, are not houses that are correct for today's Purple Martin interest.
Gourds are new again and are very popular now in the martin interest.
Today, we use 8-12 inch bottle gourds, easily grown in backyards with proper information. They are painted white to reflect heat. In this way, we can easily nestcheck our martins in season and clean the nests out in the Fall. The advantages of gourds is that they are not typically preferred by starlings and sparrows because they swing. Martins do not mind the gourd swing.