Insulation

[Jafo]

IMO wood is the best option because it is a dry heat. The insulation/moisture topic is a hot one within the yurt community. My opinion on this is basically this:

Have you ever been in an attic of a normal house? Do you see vents in there? Have you ever been in an unvented attic? It is usually full of mold and rot.

Mongolians live in a dry climate and even they leave their roof open most of the time. A yurt must be ventilated, just like any other structure, or it is going to get damp.