Small earthbags are compacted with a plate compactor.

Small earthbags are compacted with a plate compactor.


I love hearing about innovative natural building projects. Ed, a long time reader, sent me an update on his earthbag home in Ecuador. Ed is using confined earthbags that sit within a reinforced concrete frame. This is a good method for those who need to meet building code and for areas that are vulnerable to hurricanes and earthquakes.

Compacted earthbags are set within a reinforced concrete frame with barbed wire between courses.

Compacted earthbags are set within a reinforced concrete frame with barbed wire between courses.


“We finally installed the last of the roughly 2,000 bags it took to build the house. Took a bunch of pics to show the process I finally ended up with. The bags we used were smaller than what you use, compacted they are 4x9x21 inches. [This works because the bags within a concrete frame.] They weigh about 45 pounds apiece. After plastering this still gives me a wall a little over 12 inches wide. I used cadenas through out (the rebar cage that’s $19.50 for one 6 meters long and made from 3/8ths rebar), no buttresses. All bags were filled and compacted in a form then installed compacted. The last batch of bags we did I decided to keep some good records. It took 3 of us 2 hours to run enough road base through a 3/8ths screen for 55 bags. It then took us 1 hour and 15 minutes to mix about 10% clay in a cement mixer and fill the 55 bags. It took us 40 minutes to compact the 55 bags using a plate compacter I bought. It took 35 minutes to install the 55 bags. [Total time: 2 + 1.25 + .45 + .5 = approx. 4.5 hours for 3 sq.m. wall area. Also note, try to buy good soil that doesn’t require extra ingredients and mixing.]

The bags are polypropylene or as they call it here, polypropelina and cost $190 for a thousand of them. The strength of this stuff never ceases to amaze me. On the front part of the house where I have one wall that is 11 feet tall I had to pour the concrete for the bond beam single handed. My problem was how to get the concrete up the ladder because there was no way I was going to carry all of those buckets up the ladder. I decided to try an experiment so I filled a bag with wet concrete to the brim and then just stuck the hook from my chain hoist straight through the weave of the bag with no reinforcement of any kind. I then hoisted the bag to the top of the wall and emptied it. After I had hoisted the bag to the top of the wall 25 times and emptied it there was no indication of impending failure but I got scared of it so I changed the bag. I used this technique for that whole wall and never had a bag fail. I figure I have about 25 cents worth of road base in each bag. The 10% clay is free. Barbed wire is about $20 for 200 meters. Sand and gravel are $22 a meter. A 50 kg. bag of Portland cement is $8.00. I would die a happy man if they started making 25 kg. bags of cement. I pay my workers $2 and hour which is actually about 50 cents an hour above the going rate and they work like freaking mules. Really good guys.

I didn’t take pictures of the concreting but you can see finished examples in the photos. Anyway we are now done with this part and I think the house could take a direct hit from a tractor trailer traveling 50 miles and hour and all it would do is piss the house off. Let me know if you have any questions. Thanks for all of your help and if and when we ever finish it I’ll send those photos.”
Cheers,
Ed

Related:
Confined Earthbag Construction
Confined Earthbag
Interesting idea: You could build a simple foot-levered device that raises the earthbags out of the form after they’re compacted. Also note how the end product is essentially rammed earth or large compressed earth blocks (CEBs). No need for a special CEB press using this method. Resell the plate compactor when your house is finished. Rammed earth requires expensive and time consuming formwork and expensive compaction equipment.


Comments

Update on Confined Earthbag Building — 21 Comments

  1. Love this concept I just don’t get one thing , if you plaster with a natural process what do you do when you get to a concrete colum , I thought you couldn’t use natural plasters on concrete

    • Cover the concrete posts and about 12″-16″ or so of earthbags on each side with plaster mesh. Diamond mesh or professional quality stucco mesh will work better than cheap chicken mesh. This is the standard way of joining dissimilar materials.

  2. I would like to know how the concrete posts were tied into the foundation. Is the foundation for the walls separate, and then placed on top of a gravel trench? Or, is it a separate “combined” post system with footers? A small sketch would be nice with any explanation. I am attempting to design a building to pass code (Post Typhoon Hayden) in the Southern Philippines.

    Thank You for any and all information.

    Don

    • Yes, the posts are tied into the foundation with rebar. There are numerous options. The best way is to talk to a local engineer and follow their advice. Show them pictures of confined earthbag. This will help ensure the best method in your area plus be commonly understood by local builders. This last point is huge. Many workers are reluctant to use unfamiliar methods and will turn down the job or jack up the bid.

      Update: Ask around for engineers who do green building. They’ll be more open to new alternatives. Finding the right engineer will be worth it. With their help you could start a blog to document the build and become one of the go-to contacts in the Philippines. There’s lots of interest there, but it will help to clarify where to buy bags or tubes, the name of the engineer, photos, drawings, details, etc. If you do it right you’ll have one of the strongest buildings in the country. Earthbags are super strong without these added posts as evidenced in Nepal, but sometimes you have to overbuild to win over engineers and architects. They definitely understand confined masonry so they should gladly work with you. Their fee should be reasonable in the PI and worth every peso.

  3. Awesome project Ed!
    Interesting note, your earth blocks are an inch shy all around from what some local adobes are here.
    Do you think the bags are still beneficial with your soil content, awesome compaction and reinforced concrete cage?
    Did you have a typical earthbag wall experience to compare against when you made your comment about standing/working up on the wall and that it felt more stable (before concrete pour)?
    I’ve been thinking about using my buddies jumping jack tamper for ceb in a row of molds. I like your mold set in the ground.
    Also, after replacing a worn out O ring in my old pneumatictamper, it kicks hard enough that I welded on an earthbag sized plate steel base on the bottom. I’m with you Ed, mechanical compaction when possible. 50 lbs with the big plate steel on it now, so I take it up when OSHA isn’t around ;)
    Here in the US, they have half bags of Portland, a bit more money and typically special order. And thanks for the chain hoist idea, why have I been carrying 5 gallon buckets up ladders for so long when I have a chain hoist on my trailer?!

    • Two quick comments and then I’ll let Ed reply. The walls are less stable than usual to walk on because they’re only 10″ wide instead of the usual 15″. I believe the bags are still beneficial because they hold the blocks together so they can be lifted and set in the wall without breaking. The bags aren’t very expensive.

  4. The compactor is extremely heavy, maybe 200 pounds. If you are compacting the bags on the ground the compacted bags are much easier to handle than a bag that isn’t compacted. As we say in Texas the bag that isn’t compacted is kind of like trying to stick a wet noodle up a wildcats $%&. Another thing about filling on the ground that it is much more controllable and your not hauling bucket up and down a wall. Also in my mind this whole operation is much safer because you don’t have people standing on top of an unstable wall. We tried it every way possible and for us this was by far the easiest when all things were considered.

  5. I wished I young and fit. The real story is fat and 60. I used two strands of barbed wire. Didn’t ever sit down and put a calculator to it but just felt the incremental costs were minimal.

  6. This is an interesting approach to earth bags. I like the form with the compacter. I wonder if there is a way to set it on the wall so you are compacting right in place. lifting the compacted bags is an extra step.

  7. A few additional points. All of the barbed wire is tied into the rebar cages. So once concrete is poured the barbed wire becomes a structural part of the columns. Also once the bags dry they are just like cement inside. The cages do have a large footing 2 to 3 feet deep. The foundation is a trench 12 inches wide and 18 inches deep with compacted crushed rock (Comes from screening the road base)with the last 4 inches being bagged rock that keys into the trench. Once the floor is installed all of this will be completely underground. There is also a French drain in the foundation. I chose this site solely for the view which is absolutely stunning but for construction it leaves a lot to be desired so a lot of things were probably overdone. Our temp runs about 50 for a low and 70 for a high 365 days a years so I didn’t have to worry about frost issues.

  8. Quite frankly I could have probably skipped adding clay but felt the small additional cost in time was probably worth it. When we did this the mixer was stationed right by the pile of road base and the clay is great here and from the site so there was no real time involved there. So while two guys were filling and pretamping bags I was filling and running the mixer so in this case there was no real lost time but additional labor. It was very easy for me to stay ahead of them.

    • “It was very easy for me to stay ahead of them.” Must be nice to be young and fit, ha ha.

      Did you use one or two strands of barbed wire?

      Also note, buying pre-made rebar cages is less expensive than buying the same amount of rebar, at least in Ed’s case. I deleted this from your email in an effort to shorten the text, but later realized it’s an important bit of info.

  9. Question for Ed: It sounds like you could have saved about one hour on each batch of 55 bags if you didn’t have to mix clay with the soil.

    The current time is approx. 4.5 hours for 3 sq.m. wall area. So the total using good soil that could be shoveled directly into the bags would be approx. 3.5 hours, correct?

    I realize it’s not always possible to get perfect soil, but it would be interesting to see how this compares with the current total.

    Some workers could be filling the bags while others compact the bags. Comments?

  10. Mr. Geiger,
    I would like to have some information about the foundation. When building a two stories home with Earth bags or Rammed Earth, how deep should the foundation be? Is it important to pour cement for the footers? And are steel beams necessary in the basement for Earth bags homes?

    • That’s hard to answer because of the vast differences in codes, climates, soil types and your budget. I prefer super low cost building methods where there are few or no building codes, and so I most often promote earthbag foundations. Search our blog for details. Consult a knowledgeable green builder in your area for regionally specific information.

      If you have codes, then you’ll probably have to make a reinforced concrete foundation.

  11. This project probably goes into the Cutting Edge Earthbag category. He’s using smaller bags that are lighter, easier to handle and less expensive. He’s using a mechanical compactor that turns the earthbags into rammed earth or compressed earth blocks. (Ancient rammed earth structures are still standing after thousands of years: http://www.naturalbuildingblog.com/ancient-rammed-earth-structures/) The mechanical compactor eliminates hours of hard work tamping bags.

    Confined masonry is common throughout the world and so it’s well understood by engineers, architects and code officials.

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