How to Build an Earthbag Dome

Note: If you’re new to earthbag building, first read the introductory Step-by-Step Earthbag Building Instructable and How to Build an Earthbag Roundhouse . Also, my new Earthbag Building Guide and Earthbag Building DVD are now available.

We built this earthbag dome at our home in Thailand for Mother Earth News Magazine in 2007. The article that describes the complete building process in detail was published August/September 2009. It is now free on the Internet: Low-Cost Multipurpose Minibuilding Made With Earthbags , by Owen Geiger.

This earthbag dome Instructable simplifies the process and illustrates each step of construction with photos. The two critical drawings are also included here. Please refer to the complete article before asking questions.

This multi-purpose dome can serve as a storage shed or cool pantry above ground, or as a rootcellar or storm shelter below ground. No building permit is typically needed, because it is below the minimum size required by building codes, is not inhabited and is not attached to a residence.

Earthbag structures provide a cool space in summer and an escape from the cold in winter (ideal for humans and animals), which means this earthbag dome is well suited for many purposes, like a quiet space for relaxing or playing music, as well as those listed previously. Depending on your needs, the most practical combination of uses might be a rootcellar/cool pantry for daily use and a disaster shelter for emergencies such as tornadoes or hurricanes.

The key concept that makes earthbag domes work is corbelling. This means each course (each row) of bags is inset slightly from the course below. Corbelled domes made of adobe and stone have been built for thousands of years. The concept has been applied to earthbags in the last few decades.

Basic project information:
18’ exterior diameter; 8’ interior diameter; 11’ exterior diameter, 50 sq. ft. interior floor space; total cost of materials: $300, which is about $6/square foot.

Tools:
Tamper(s), round nose shovel(s), grape hoe or grub hoe (digging tool), 13” x 16” sheetmetal slider, knife, hammer, 2’ level, 2” x 4” x 10’ leveling board, tape measure, fencing pliers, handsaw, trowel, garden hose with spray nozzle, 6’ or 8’ stepladder

The following instructions assume you have cleared and leveled the site, removed topsoil, positioned fill soil around the building site to minimize work, dug a trench to stable subsoil, put about 12” of gravel in the trench, and added two stakes with string lines: a center stake with string line to measure the radius, and a stake in front of the door to measure the dome curvature. Bags or tubes can be used. We demonstrate bags, because they’re often available recycled for very low cost. My YouTube Channel has a short video showing how the dome was built.

Step 1 Dome Plans

Let’s briefly take a look at the plans so you’ll better understand the building process. The first drawing is the floorplan that shows the dimensions for the dome base and the angled buttresses in front. The buttresses provide reinforcing on both sides of the door and also act as retaining walls to hold back the earth. Make a rubble trench under the buttresses the same as the dome, and interlock (overlap) each course where the dome and buttresses intersect.

The second drawing is the dome section that shows key vertical dimensions, earthbag foundation, door and arch. Note the wood stake in front of the door. The string line on this stake guides the curvature of the dome (112” radius in this case). This dimension remains constant. Put the stake off to one side of the doorway so you’re not tripping on it during construction.

Comments

[iSurgeon]

So, what is that on top of the barbed wire? Is that to hold it in place? Is it temporary or does it become part of the structure?

[Owen Geiger]

Those are bricks to hold the barbed wire in place. Be careful because it can spring up and cut you.

[patron_zero]

I've been looking for a 'landscape-friendly' design for a doghouse, more play yard day shelter, for our mutts, this looks to be very promising !

[Arghus]

would it be a problem going up a floor? and in what country u build these houses?

[Owen Geiger]

The first floor can easily support a second floor, but lifting heavy soil high in the air is difficult. It would be more efficient to build a lightweight second story. Earthbag houses are being built all over the world. Our blog has readers from about 100 countries, and we've profiled completed projects in dozens of countries.

[benedict688]

Looks cool, but I wonder what you could do to make it stronger against earthquakes. I know the foundation wouldn't be legal in california, and Im not sure about the rest of it.

[Owen Geiger]

We have loads of information on making earthbag buildings earthquake resistant, because many earthbag projects are in seismic areas. Search our Earthbag Building Blog at http://earthbagbuilding.wordpress.com/, EarthbagBuilding.com and EarthbagStructures.com. You can get code approval and you can make them extremely earthquake resistant (among the strongest buildings in the world).

[danzo321]

Thinking this would be a great d-i-y storm shelter.

[danzo321]

I was thinking these bags might be kind of slippery.

[Owen Geiger]

Barbed wire between courses prevents slippage.

[Mr.Yoness]

Oh, that makes sense. Sooo cool!!! I think i will make one for my backyard!

[cincymikeb]

Awesome instructible . I was thinking about a domed roof made of wine bottles and concrete . I have seen walls made this way .Its surely not practical but think how cool it would look !
,I'm sure it's possible but curious about your thoughts ?

[Owen Geiger]

Cement tends to shrink as it dries. You'd likely have small gaps around the bottles from the shrinkage. One option is to mix sawdust with cement or lime to reduce shrinkage. But again, this wouldn't be real durable on domes. Roofed structures provide much greater protection.

[spark master]

this was done , and published in Mother Earth News many many years ago, try their web site to find it for details. They used wine bots/beer cans/everything anything hollow to lighten the load. And an internal or garden privacy wall made like this with wine bots would be stunning (nice blue bottles blocking the solar axial path .

[Owen Geiger]

That sounds interesting, but it would be prone to leaks and overheating.

[Mr.Yoness]

Awesome 'ible'!!! How safe is it? I'm just not sure how the bags stay together without caving in...

[Owen Geiger]

Domes are one of the strongest shapes in nature. You could drive a tractor or truck over the top. The bags hold together because 1. they're tamped solid (which has extremely high compressive strength -- 10x wood framed walls), 2. barbed wire prevents slippage between bags.

Be sure to check out our earthbag blog and other websites for complete info.
http://earthbagbuilding.wordpress.com/

[danzo321]

If you had included capped 2-liter soda bottles, squashing the dirtbags against them, you'd have skylights. Wouldn't work with the grass layer, but what other toppings have you considered?

[Anianna]

If I were to dig a whole, say 3-4 ft at its deepest point, in a hillside, would I have to build from the bottom of the hole up or could I simply build a roof starting at the top edge of the hole and building up into a dome? We have very firm soil; very hard to dig.

[Owen Geiger]

You could do that with a lightweight roof like a traditional wickiup made with bent saplings. This would create a small, simple shelter.

But you can't build an earthbag wall or other heavy wall the way you describe or the sides would collapse.

[Anianna]

Thank you very much.

[triumphman]

No way could I feel safe in there! Cave- ins being deadly. Sorry, I would not let my dog sleep in there. Ok, for Hobbits, I guess.

[triumphman]

I would be concerned with being buried under all that weight when it caves in! I could never get a good nights rest either. That is a lot of work and resources. You have to have all that material at hand. I can't see it being worthwhile. Nice if you are a Hobbit. But they had round doors. They were kind of round anyway. Thanks for sharing this labor intensive 'ible.

[Oshgood]

Beautiful instructable! Beautiful process! Beautiful results!
Thank you for sharing this... It´s beautiful! I am going to build my own house soon and this method looks very interesting.

Love frome chile!

Eugenio

[Redstormx1]

It would also slow down thieves who simply dig there way through your walls .

[Owen Geiger]

You think they're going to 'dig' through 2" of plaster plus 15" of hard tamped earth and 2" more plaster without somebody noticing? I'm pretty sure they'll pick easier targets like 2x4 houses.

[Redstormx1]

What kind of lawn mower is use to trim the grass ?

[Owen Geiger]

We use a weed whip and sometimes pruning shears on top about 2-3 times a year when it gets really tall. My friend says we have to cut the grass before it goes to seed or it will die and then we would have to resod the dome.

[supershot1]

how much are the earthbags alone??

[theshedlife]

about 12 hours a day?

[Owen Geiger]

Not sure what you're saying. I sure don't work outside 12 hours a day. Most of my time is spent researching, writing and designing houses. The earthbag dome was finished a little at a time on weekends.

[Owen Geiger]

You have to shop around just like anything. Prices range from 6 cents (our latest price for recycled bags in new condition) up to 45 cents or so each.

[Zdaddy]

Mildew?

[mrwaffles2]

wow... amazing

[ramesh babu]

Its great and very nice sir,but you provide a arch to this dome is it stability for long time,however it is incredible.

[Owen Geiger]

Arches can last thousands of years. Look it up on Google.

[mgalyean]

How easy is it to repair a leak if one develops compared to a shed built normally? I guess I'm getting at how "maintainable" is the structure compared to something which has a structure more exposed to maintenance and less "woven" and "integrated" to the extent that it can be hard to replace/repair a section (perhaps damaged by rodents) without risking structural failure.

Be that as it may, I'm thinking an alternate construction technique that might be quite a bit less labor intensive would be to create a large compacted mound of the correct dirt type using a front loader, then progressively hollow it out while reinforcing using standard tunneling/mining techniques, then finish up with a layer of sprayed in rebar'd concrete on the interior if so desired. If a layer of gravel could somehow be engineered between the concrete and the dirt you'd get nice drainage to the periphery and leaks would be minimized. I just can't help thinking about all the plastic for the dirt bags and the 6 mil for preventing leaks and how it might be avoided. Gravel drains nicely generally.

[Owen Geiger]

You're describing ferrocement. That's a good way to build, although you'll still have to be careful to waterproof everything carefully. You don't need to make an earth mound. Just form the rebar in the desired shape and cover with at least 1-2 layers of plaster mesh. You can get the details on the Internet for free.

You can also combine earthbags with ferrocement to insulate the building. I've been describing my ideas on how to do this on our Earthbag Building Blog: http://earthbagbuilding.wordpress.com/

You can fill the bags with various types of insulation. Or you can fill bags or tubes with geopolymer. The bags or tubes are stacked next to the ferrocement frame and tied to it. The geopolymer can be lightweight and insulating. http://earthbagbuilding.wordpress.com/2011/09/23/lightweight-insulating-geopolymer-earthbags-part-3/

[bvis]

Ahhh the bottom rung is the only one with Gravel. The rest is earth. Very nice.

[Owen Geiger]

The bottom two courses of bags are filled with gravel. This photo shows the 2nd course.