Has anyone out there ever made one of these forest huts.

 I think I could figure it out, but I am not sure about foundation and waterproofing method
http://www.svenskaturistforeningen.se/en/Discover-Sweden/Facilities-and-activities/Vastmanland/Vandrarhem/STF-Hostel-KolarbynSkinnskatteberg/Pictures/

Picture of Has anyone out there ever made one of these forest huts.
Looks like corrugated steal on the inside. May just be overlapping planks. It would need to be pretty heavy duty no matter what it is to take the weight of the dirt and moss. The angle of the hut and the dirt will help prevent water from coming in.