Based on that and subsequent input, here's a sketch of the side view of the design I'm presently favoring.
The earth bag walls go straight up with periodic buttresses along the horizontal length. At 8 feet up will be the floor joists, then the straight earth bag walls will end up another two feet. At that point will start the 10-foot radius concrete dome, which will have insulation around it. So the parabolic, catenary arch has been nixed. We're still sticking with the slight arch as the house goes east and west, concave to the north to help the house resist the backfill. Torg also recommended having anchors out in the back-fill, tied to the earth bag wall. The east and west ends of the house will still be rounded. Torg pointed out that having the north wall convex to the backfill would tend to wall failure, whereas having the north side concave to the backfill would tend to the earth packing the wall tighter -- the arch principle.
Torg suggested that I not use any cement in the earth bags, saying that cement will crack in the event of an earthquake or settling, whereas rammed earth in the earth bags will just “reanneal”.
Regarding most of our building time being through the winder, per the 180-days provided by the 1031 roll-over, John Day suggested that I use a "high tunnel" cover over the site. This could entail using pvc pipe with plastic overlaid, and some kind of heater inside, e.g. propane, augmented with a rocket stove. This would enable us to build through freezing temperatures outside.
I'm wondering if this is a plausible approach. How much PVC pipe and plastic will that require; and how hard will that temporary shelter be to build? How much energy will it take to heat to prevent freezing?
Another question I have regards storage. What would be the best way to store my building supplies and other things while we are building?
Torg said that even with the compact earth, not using cement, we would want to keep the structure above freezing so that the wetted earth can properly dry.
In addition to his other skills, Torg also is an architect (not presently licensed in Utah). He said he could draw up our plans, including the electrical, plumbing (including rainwater capture, cisterns, and compost tank for the main restroom), and engineering aspects; and he has an associate who is a licensed Engineer in Utah, who could then sign off on the plans.
I'll need to decide what appliances and how many will be AC versus DC for each room, to determine how many lines to run to that room. In earth bag construction, the wiring and plumbing is laid down as you go. You don't want to run conduit, because the metal tends to bend from the compacting process.
One of the things the community is talking about getting right away is a track hoe for excavation, road building, back filling etc. By the time we rent a track hoe for the various homes we want to build on the site, we will have paid for the track hoe; and we can get our money back out of the track hoe when we're done.
That sounds nice, except that up front we are strapped for cash, so I would rather rent at first. Aaron N. knows two people with track hoes.
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