posted 7 years ago
Earthbags could work, but will be stronger if the walls are curved out a bit. Check out MyLittleHomestead on Youtube to see their earthbag buildings, one of them has a lower level below grade but it is a circle so it will have great strength due to that. Tying in several deadman for straighter walls will complicate the waterproofing unless you plan to leave out the plastic sheeting against the walls and stick to only the umbrella, which I wouldn't recommend.
Wooden posts say every 8-10 feet with earth bags as filler, with a bit or arc bowing out towards the surrounding earth should resist the soil pressure and still allow you to place sheeting along the outside for water protection. I'm not an engineer though, so overbuild if you don't hire one to calculate loads for you. Saturated soil plus snow load, plus the weight of you or whatever might walk on the roof can add up!
The holy trinity of wholesomeness: Fred Rogers - be kind to others; Steve Irwin - be kind to animals; Bob Ross - be kind to yourself