Site-built construction must deal with problems associated with an outdoor site.
There may be a large amount of waste as materials left unused are often disposed of instead of recycled. Inclement weather and inadequate storage can damage materials.
Lumber and other supplies must be dealt with where they are dropped off by supply trucks. Open sites are vulnerable to theft and vandalism. Also, those working on the house must deal with inclement weather, such as cold, high heat, high humidity, and rain.