Most mobiles use some form of roof trusses. The pole barn style roof is the most secure style, but many use 2x"s screwed to the trusses with steel panels you can use foam between the old & new roof for added insulation. Remember that by design, weight is always an issue with roofs on mobiles
Lots of info on roofs here and everything else here.
http://www.mobilehomerepair.com/phpbb/
Lots of info on roofs here and everything else here.
http://www.mobilehomerepair.com/phpbb/