It started out as a reply to a comment, and it ended up becoming a post so here it is…
The foundation was what we spent most of our time and energy on, and our biggest frustration. If we had the money before we started, we would have consulted with a professional. The french drain was overkill since we get about 1′ of rain a year, but we didn’t understand how the ground absorbed it really well until after our first year of living here. And we didn’t use any special fill for the stemwall. The temperature stays comfortable inside, even with a single wood stove… especially when it got down to -20 degrees. And we’ve had no problems with the dome structure so far.
Doors & Windows
Figuring out how to put in the door/s and windows… and dealing with the slant… Make sure your window and door forms are sturdy on the sides. We used OSB and after a while had a tendency to bow inward when we stacked bags against them. Not a show-stopper, but a pain when you finally plaster that area. We ended up using a rubber mallet to pound the stray bag into place before plastering over it.
The wood stove residing in the middle of the main dome was doable for the first year, but a pain to move around without bumping into it, and again with the slant of the dome itself makes it hard to build an exit for the stove pipe, and keep the integrity of the bags intact, and keep the pipe far enough away from the structure. We ended up moving the stove to the side and adding two 90 degree elbows to the stove pipe. You have to remove that section of the pipe to clean, but you have more room in the center of the dome. Which is good when you add a dog and cat to the mix. Also, our rafters served as a fixture to secure the stove pipe box, so that worked out… and we really didn’t need to use double-wall pipe at the top (exiting out of the dome top). The pipe wasn’t even hot by the time it reached the rafters at 12’… so overkill and a waste of money on the double-wall stove pipe.
We didn’t buy UV protected bags… (in hindsight… not very smart). With our altitude 4200 ft. leaving our bags uncovered during the summer made them brittle and prone to just looking at them and having them split open and a flow of scoria come flowing out of the bag. So spend the extra money for UV protected/treated bags. Don’t be cheap.
Scaffolding & Hoist System
Make sure you have some kind of scaffolding when you build above your own body height. And prepare to lift heavy bags of scoria (about 40-45 lbs each, but still a lot less than dirt). The rafters you see in the photos were only put in place because we didn’t have scaffolding to complete the main dome from 12 ft (rafter height) to 18 ft (top of dome) We used the back of the pickup bed, to the (now removed mine-shaft entrance), to the outside rafters (with OSB screwed to the top as a platform), and muscled the bags the remainder of the way. (I suggest you invest in some sort of a hoist system and don’t put your wife through the agony of schlepping bags 12′ to 18′ up.)
Trying to get it all done in three months with just a husband and wife team… We lived in our VW from June 1 to mid-October. But since it rained 3 out of 4 weeks in June, while we were still building the shed to store what stuff we have, we didn’t start on the dome until July 9 and finished it just enough to move in with one week to spare before the first major snow storm hit.
Unless you live in a dry arid climate… stay away from mud and cob as your exterior plaster. (On second thought… stay away from it period because it needs an overhang.) Had we the luxury of time and good warm weather we would have at least applied a layer of papercrete. Instead, we needed a covering to protect the bags from the sun and seal them from the snow… so mud/cob was the quickest option. It came back to haunt us in the spring when we had a torrential rain storm which washed the mud off the dome, soaked the bags and turned the entire living interior into a rain forest. We had to sleep under a plastic sheet that evening. And it leaked EVERYWHERE! It was the lowest most demoralizing point of our whole experience to date. (Except watching an earthworm crawling through the wall while we were eating.)
We are still in the process of plastering the remaining exterior with a second layer, and still in the process of plastering the interior with its first layer. The papercrete has worked well, but it is… a pain to process. You need a lot (I stress… A LOT!) of shredded newspaper. Unless you know someone with an industrial document shredder you will end up using thrift store document shredders (for $5 a piece) that overheat every 5-10 minutes… so buy a few of them. While one is cooling off you can move to the next shredder and continue. It takes about four hours to fill a 55 gallon water barrel with shredded newspaper. We got our newspaper when we head into town. We stop by the newspaper recycling bin, one climbs in and hands the other handfuls of newspapers. Make sure you say hello to the unsuspecting recycler who opens the trap door on the other side to dump their newspapers in the bin. I usually say… “Hello, I’ll take those for you. Thanks for recycling with us.”
More info will be added when we think of it.