For several years, Kelly and I have been filtering all the best earthbag content from the Web, writing extensively on all aspects of earthbag building and organizing the information for readers. There’s now an enormous amount of information available – so much that it’s difficult to keep up with everything. That’s one reason why our sites are helpful. We gather the best information so you don’t have to spend endless hours looking for it, wasting time clicking through low quality sites, blurry videos, etc. No one else has anything close to this amount of content. Below are just a few links from EarthbagBuilding.com (the mothership) and our Earthbag Building Blog. Also note how we strive to keep all these pages up to date so readers aren’t faced with a bunch of broken links. (And it’s free.)
Earthbag Projects and Pictures
Earthbag Videos
Earthbag Articles
Earthbag Testing
Earthbag Blogs (recently updated and expanded to include earthbag blogs in Spanish)
When stabilizing clay with lime what is the correct ratio? What is the minimal depth of the foundation footing trench necessary when things like frost and water table are not an issue? If one is able to keep heavy clay soils dry what is the impact of using these soil right out of the ground?
Earthbag soil mix doesn’t have to be perfect and it usually doesn’t have to be stabilized. Most any soil will work, even typical clay subsoil. Try hard to minimize extra mixing to save labor. Try to find a soil that’s ‘good enough’ and doesn’t need amended. Amending the soil can double or triple the labor. I suggest buying road base, etc. that is ‘shovel read’ — it can be placed into the bags as is. Make sample bags and test them for hardness when they dry. It would be less expensive to mix in sand than lime. If you do use lime (make test bags) then experiment with how much lime is needed. There are many kinds of soil and the only way to know what works is by experimenting or talking to a professional in your area who knows the local soils. Keep the soil dry in the wall and almost any soil will work.
Some people have built right on grade — right on the ground level. This is risky because the ground could settle or get washed away in a flood. I highly suggest 1′-2′ deep rubble trench to support the heavy walls and help drain water away. Use double bags of gravel on at least 1-2 courses of earthbags to prevent wicking of moisture.
Owen’s advice is solid.
I would suggest one additional thought.
As far as how deep your foundation should be, I would suggest seeking out experienced builders in your local area. Those builders most likely will not be familiar with earthbag foundation, but don’t let that deter you from seeking their wisdom. They will understand the local soil conditions, frost conditions, water tables, etc. They will already know and understand how deep a foundation must be in your area to be strong and stable. They will know what your local subsoil can support.
When seeking local advice, I encourage you to find old timers that have experience building using more traditional techniques. Older stone masonry foundations are excellent indicators. So are old dry stacked stone foundations. If you find a consistent pattern about how deep wide and thick those old foundations are, you can get a very good idea about how a gravel filled earthbag foundation of similar dimensions will perform in your local area.
Find older structures in your area similar in size to what you wish to build that were built using those old techniques and look them over closely. Learn what has been proven to work well in your area in the past. Take that wisdom and incorporate it into your structure.
This need not be a difficult process. Just pay attention during your normal daily activities as you travel in your area. Look for those old structures. Don’t be ashamed to stop and ask the owner if you can look it over and perhaps learn more about how it was constructed. Most owners will be more than happy to oblige. Take a few photos. If the homeowner is willing to allow it, you can take a metal rod, such as a piece of rebar, and pound it into the ground next to the foundation at various angles next to the foundation to try to determine how deep the foundation goes. Of course, this metal rod technique is not effective for foundations that include a full basement. Old full basement foundations are best observed from the inside.
Modern foundation contractors almost always will be less helpful than the old timers. The younger generations will tend to say that their modern “poured concrete” way is the only way. Don’t let their skepticism fool you.
The old timers won’t know much about earthbags either, but they will have a much broader understanding about what is possible using alternative techniques. Seek their wisdom. You’ll learn a lot and be very glad you did.
Good advice. Thanks for sharing. Soil and climate conditions vary widely and so it’s always good to talk to experienced builders in your area.
You guys are doing a great service and I am always interested to discover what else is going on in the world of earthbags and alternatives. Hoping that one day you’ll get down to Patagonai to check out our little thing in person.
Thanks Paul. Kelly and I have been following your work for a long time. You’ve been a major inspiration to others in earthbag building and the larger environmental movement. I’d love to visit someday. See what happens. I’m not really traveling much these days.
Dear Owen, thank you so much for all your’s answres. It’s was very helpfull for me, and I find almoust all my answers in your blog. But, becouse you have so much information, and because some time I don’t find quicly exactly what I want, I stil have some question:
The wall it’s still breatheable because of the polipropilene bags? And how much it’s take for the wall to dry (in general)? I already start to fill some bags(with yellow clay and sand) and the rain came and I let them with no cover, and of course now they are more moist inside. It can be afected the wall because of this,( because I want to keep builning in this winter)?
You have any ideea about a under house room (for kiping the fruit and vegetables ), if it’s ok to put all around of this room, bags fill with gravel?
Thank you, thank you, thank you…
Hi Angie, you want the walls to dry out before winter. Otherwise the moisture in the soil will freeze and expand and break up the soil. Standard woven poly bags will allow moisture to pass through, but mesh bags will speed drying considerably. Also, it’s good to drape some plastic or tarps across the tops of walls to keep rain off.
Yes, you can build a rootcellar with bags of gravel if it’s designed correctly. (Free rootcellar design coming soon.) You need to reinforce the walls to resist the horizontal thrust of the soil and keep out moisture with plastic.
We really appreciate the time and effort you have put into your site and gathering all the information from the web. We are totally enamored by the concept and process of earthbag building. Having spent the last several weeks and month poring over this site and links we are about to start on our first structure a 6 meter dome (although we are now considering doing a practice smaller 2.5 meter dome to break our teeth on) Our question is this: Our big 6 meter diameter foundation trench has been dug out / into a shallow gradient hillside – one third of the circle is between 1.5 meters sloping to 50 centimeters underground. We are planning to start the spring line two bags up from the level ground and back fill the space into the hill. Will the preassure of the backfilled earth and hillside jeopardize its structural integrity? there are no We are going to have buttressing either side of our two doors which are on opposite sides of the dome – is this enough or would you recommend additional buttressing to be on the safe side? Finally we are building with bags not tubes as we were not able to purchase tubes where we are (Cyprus, EU) We would really appreciate any advice/ guidance you could offer us and can happily supply more information/ photos of the site.
Thanks. No problem with the back fill against the dome. Domes are very strong. Note my dome toolshed that’s buried in earth. It never budged at all. http://www.instructables.com/id/How-to-Build-an-Earthbag-Dome/
You two are doing an excellent job of informing the world of EB-ing. I commend you wholeheartedly. Thank you for all your work and effort!
It wouldn’t surprise me to see in the future even more categories, such as EB in Earthquake areas with heavy rainfall. How to water proof your Dome, plan for eaves, insulate, types of shingles and shakes and liscence plates. I’d love one covered in copper tiles… :)