Step 17: Conclusion
Domes are the strongest form in nature and easily support enormous forces. We added about 20 truck loads of soil on the dome without it moving one bit. I’m confident another 100 truck loads could be put directly on top and it wouldn’t make any difference, because the dome is all in compression, and tamped earth (road base in our case) can support very high loads. So if you want to build underground, domes are a good way to go – that or roundhouses. Both gain their strength from the circle: forces (loads) are transferred directly to the ground. There are no components to fail as in post and beam or wood frame walls.
Domes have lots of other advantages. They create the most floor space for a given length of wall. There are no wasted corners. The feeling inside is magical. Those who live in domes (and roundhouses) most likely never live in boxes again. Wind flows around domes and does not build up pressure against them. You can build domes without wood. You can build domes with minimal tools and materials – no nails, no wood, no plywood, no shingles. This makes domes a good candidate for those who lack carpentry skills and for emergency shelters for disaster areas and war refugees. Give people some rice or grain bags and a little training, and soon they can build their own sturdy, safe shelters.
But no building system is perfect for all climates and situations. For instance, domes are not culturally accepted in some areas. Domes evolved in desert regions where wood was scarce, and are not the best choice in rainy climates. They’re exposed to the elements and vulnerable to leaks. It’s difficult to get a perfect plaster job that doesn’t leak. A leak could soften the soil and cause the dome to collapse, so the fill soil has to be stabilized, which adds to the labor and expense. For this reason we typically advise against domes in rainy climates, but this is not to say it can’t be done. There’s a dome in Koh Phangan, Thailand where it rains almost constantly for months at a time, and it hasn’t leaked yet. It was built by Phangan Earthworks with expert plasterer’s. However, few people can match this skill level, even those who do plaster work for a living. Plastered domes are particularly risky where there are freeze/thaw cycles. Water will get into every little crack (plaster always has small cracks) and burst the plaster when it freezes. That’s how nature turns mountains of stone into sand and gravel…
So the choice is yours. Domes are enormously popular among earthbag builders. If you live in a rainy climate, you could build a dome with a living roof like we did. We’ve had no leaks so far. Another good option is to build a roofed dome like the Kentucky Dome Home .
Photos: Meemee Kanyarath