There’s great, untapped potential for superinsulated earthbag buildings in cold climates. Here’s a way to combine the best features of earthbags and yurts. The basic idea is to combine earthbag walls filled with lightweight insulation such as scoria (lava rock), with a traditional yurt roof frame that’s insulated with perlite or vermiculite.
Yurts (ghers) have been used in Mongolia and other areas for centuries. Traditional yurts are well suited for cold, windy places, in part because the wind just blows around them. They can, however, be made even more comfortable with extra insulation in earthbags.
Scoria is perfect for superinsulated earthbag walls: low cost, all natural, rot proof, fireproof, doesn’t attract pests, lightweight and easy to work with. Scoria is great for building walls since the aggregates tend to lock together and form stable walls. Tie courses together with twine for best results, and then cover walls with canvas.
Yurt roof frames are readily available through numerous suppliers, and fast and easy to assemble. The steel tension cable is strong yet light. They are very resource efficient, using minimal wood, but often lack adequate insulation. I recommend tying bags of lightweight insulation to the bottom of the frame. Perlite and vermiculite would be excellent choices for ceiling insulation since they’re very lightweight.
This design is portable, just like traditional yurts. The entire structure can be disassembled and transported if necessary. This would be a dream structure for places like Minnesota, Canada, Alaska, Siberia and Mongolia because it would be super comfortable, inexpensive, portable, wind resistant, owner built and could be built in many sizes. Add a skylight, rocket stove, small solar panel and composting toilet and then you can laugh at the wind howling by.
Note: you can use recycled bags if available (often farmers have them). You can also order tubes from poly bag suppliers. They make custom sizes. Tubes are faster to fill since you don’t have to stop and tie the ends as often. A 12″ tube (measured when empty) that provides 10″ of insulation when filled would be ideal for many cold climates. Simply tie the tubes to the yurt frame with twine. Use whatever insulation is most practical in your area.