How to Build an Earthbag Dome

Step 10 Angle Ends of Bags Toward the Center

On straight earthbag walls, you can just butt the bags against each other. But for roundhouses and domes, you need to align the bag ends to the center point so the bags sit tightly against each other. Hit the bottom of each bag with a board until it aligns with the center of the dome. The second photo shows how the bag joints appear looking from above. (They look like mitered joints.) Repeat this process throughout the dome. At the top, the process becomes more pronounced as the radius decreases.

Comments

[D00M99]

When you say to hit the bottom of the bag until it aligns with the center what does that mean? I don't quite understand which specific side it is.

[Owen Geiger]

Bags are filled in an upright position in place on the wall. So obviously the bottom of the bag is ... on the bottom. Tilt the bag into place when it's full. Then hit the bottom of the bag to align with the center point of the dome or roundhouse. This typically involves 1-3 smacks with a 2x4. Sometimes I just give it a kick with my foot.

[frazjef]

Thanks so much. I live in Mali where the vast majority of people build with dirt anyway. I'm praying that these techniques will increase their standard of living.
Quick question: "How do I know how much to reduce the size of each successive layer?"

[Owen Geiger]

Each course is the same size.

On a related note: Fill bags to maximum capacity so you don't need so many bags and so there's more overlap between courses.

[mrguy19187]

I think frazjef might have meant to ask: as you go up the dome, how does one know what amount to decrease the circumference of each successive course in order to make the dome shape look right and be stable.

[Owen Geiger]

Just follow the radius of the rope that's stretched from the front door. There's nothing to figure out. It's virtually foolproof.

There are other methods of building domes that will create different shapes: catenary and volcano shaped domes. Each has advantages.