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 is 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

[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.

[poza]

why not use gravel for all the courses? is there a benefit (other than $$) to using soil on the upper courses?

[Owen Geiger]

You can use gravel bags to get above where moisture can cause damage, but too high and then the wall becomes unstable.

[Win Guy]

Cool! My father wants to do something like this on his property. I should show him this!
Win Guy

[kwood4]

I currently live in my straw bale house, here in Ontario. I need a root cellar. Would this structure make a good root cellar? should I build it into the side of a hill , or on the level ground and surround it with earth? Would love to hear your feedback. In Ontario we can get down to -25 C in the winter and ++ 30 with high humidity in the summer.
thanks for your great video - most useful and I will repost on my blog at EcoStrawHouse.com

[Owen Geiger]

Sure, that's one of the best uses. You can build into a hillside or backfill as you say. It's easier to build into a hillside since you don't have to add as much soil around it later. Make sure you use enough layers of plastic to keep water out.

[yikesitsmindy]

This is a beautiful structure. I would love to see the inside. How do you think this would hold up in New Jersey? We have a wide range of weather conditions 12 inches of rain last week and 2 feet of snow 3 months from now.

[Owen Geiger]

It should hold up just fine. Raise the site well above flood stage, slope the ground away from the dome, use gravel bags on lower courses and use EPDM rubber membrane over the top. Be careful not to puncture it while adding soil on top.

For even greater durability, you could add lime or cement to the soil mix. Stabilized soil will hold up even under water.

[SIRJAMES09]

this is AWESOME!!! I would love to have a home like this!!TY for sharing Sir.

[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]

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

[sunshiine]

This is absolutely amazing! I want one! I can't wait to show the real builder! Thanks for sharing your stuff!

[grimshade]

How can I calculate the number of bags involved in a corbelled, caternary arch? The figures in Kaki Hunter's book only account for straight walls. Do you have any good ideas for getting an approximation for the math, at least?

[husamwadi]

ITS SHREK TIME!!!!

[The nerdling]

that is so cool.
if i make one i will do it into a ledge which is at my place make it really big and put lights in it then use it as my lab, oh yeh and put windows and a put belly stove in it

[urtlesquirt]

GANDALF NOOOOOOOOOOOOO!!

[hohum]

Might you consider an intern for your next project---ME

I am tired of paying rent,

I can do:
stained glass
weld, STICK, MIG, TIG, O/A, PLASMA
ceramics
blacksmithing
built a COB wall
chair caning
fiberglass
wood working

operate:
mill
lathe
gear hob
most any hand tool
air/hydraulic

fast learner.

[mark429]

Wow, want free room & board in Upstate NY? I could use an indentured servant,err I mean "intern" j/k =)

That is an impressive skill set ya got there... cheers and good luck!

[npknhdfrvr]

It's like a real-life hobbit hole

[VianPatyr]

Viry nice post. Is it possible to add some additional rooms to this dome to make more space? I have seen some such buildings in Mari El, they are called <;0=45 ?ç@B

[Owen Geiger]

Oh sure. Lots of people are building dome clusters. It's easier to build multiple small domes than large domes.

[iminthebathroom]

Wish one of these would work where I live. Northwestern BC, pacific rain forest.

[Owen Geiger]

There's a Cal-earth dome in BC. I saw their real estate listing. They built with stabilized earth. I recommend using some insulation. (Maybe their house was too cold and that's why they were selling it.)

You can build a roofed dome for greater protection. Keep searching our sites. All these topics are covered for free.

[iminthebathroom]

interesting, i wonder where in BC though, our geography varies such that microclimates are a given. I'm in Kitimat, translates as "people of the snow" Really should read "soggy people" I used to live in Montreal, Quebec and we way more snow and colder temperatures. Average cold in the winter is -12, summers up to the extreme of +42 with an average of +26. Regardless it rains a lot, not in down pours but a constant mist. I'll have to look into to it, not so much for a domicile but a cabin of sorts. Thanks again!

[Owen Geiger]

Be sure to read How to Build an Insulated Earthbag House
http://www.instructables.com/id/How-to-Build-an-Insulated-Earthbag-House/