With all due respect, and having consulted the Wise Lady from Philadelphia, the cost of putting down 6 mil poly as a ground vapor barrier under a mobile home costs less than $60. U.S. If I were selling a home and if that were the only concern raised by a buyer I would leap into...
I don't have a perm rating yet but 6 mil polyethylene has a perm rating of about 0.06 - very low. That would explain why, if I guess right, the product is micro-perforated to let it breathe moisture vapor out while keeping actual water out. OPINION: I prefer the non-plastic house...