Not Concrete

Joe, you really should look into ferrocement as a design option. Steel reinforcement bar is comparatively inexpensive and easy to shape for framing and so is the galvanized "chicken wire" mesh used to "wrap" the frame. You then use little cement, as it is stuccoed onto both sides (inner and outer) of the layers of mesh and frame. Many ship hulls have been made using this sturdy, thin-shell concrete method of construction, as it is much cheaper than steel. Find the Concrete Dome instructions for detailed instructions. This design is already there for you. Built properly, will be earthquake, wind and falling-tree resistant. It won't float, however. Consider building it on higher ground.

Offered by Granville.

I'm really wanting to get away from concrete as an answer too, because of the large amount needed and high expense.

Offered by Joe.

Why Gunite? Why not take the simplest, economical approach? After you apply enough layers of mesh, you trowel the mixture on with a hand trowel, keeping a wet edge. First trowel from the inside, then the outside. Skip the plastic tarp, which would weaken the structure. If you doubt these methods, I suggest you look up ferro-cement under the heading of ship-building.

Offered by Granville.