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.
“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 required 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.”
Confined Earthbag Construction
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.