>>597427Hmm I'm not sure will there be no mold between the layers of polyethylene, but Mike Oehler of the "50 dollar and up underground house book" fame seems to use this system for roofs and his buildings stood up quite well. There should be sufficient ventilation since with my craftsmanship the door would be nowhere near airtight and it should provide some nice draw from the outside to the stove and chimney. Alternatively it would be quite simple to add a small window or airhole for ventilation. But yeah it would probably be only used for sleeping since the ceiling would be low I just based the internal layout on the Finnish goahti or lavvu where the fire is in the middle (attaching a shitty pic).
However I could move the stove closer to the side opposite the entrance, that would free up some space. The crawlspaces would be used for storing stuff, tools so the space would not be completely wasted. And I've already scavenged some clay firebricks to lay around the stove, that would add a bit of safety as well as heat retention.