PreFab homes are built in climate controlled factories and they have come a long way. The timeline is also much shorter from purchase to installation. Depending on where a person lives the building of a home can take anywhere from 3 months to a year because of weather conditions. The cost may be a little more but one thing also is the labor. Workers show up more at a build when the weather is just right. My cousin worked in one of those factories and conditions were perfect. If it's too hot or too cold many contract workers always have some excuse not to work. Also remember they are not the same as a mobile home (an axle base).