What Can I Put in my Earthbags?
This is a question that seems to come up quite a lot in various forms, so I’ve decided to write a post on it.
What Can I Put in my Earthbags?
The answer is: It depends what you want to do with them.
If you want superadobe, which is a specific technique to create solid clay/mud bricks by allowing the mixture to cure on the wall, then you need an damp earth-clay mix. About 20-30% clay is ideal. The mud needs to stick together in a ball when you roll it in your hand. It shouldn’t be breaking up like oatmeal.
What’s the big deal about superadobe? With superadobe, the earthbags cure on the wall, and once dry are rock solid WITH OR WITHOUT THE BAGS. A friend of mine forgot a stove pipe hole in his superadobe wall. In the end he had to dig out a hole with a teaspoon because the walls were so darn solid. He said it was like escape from Colditz:) You could burn the bags off, and your building would stay standing.
Experiments have shown you can add things into the damp clay-earth mix without too much impact, especially if the bags are left intact. Stones less than an inch (2-3 cm) in width can be left in. Some people have added things like pumice for insulation.
Stabilized bags for foundations.
You can mix your mud with lime to stabilize it for foundations, which obviously see a lot more water and pressure than the rest of your walls. You can also fill them with limecrete, gravel, or a mixture of both for the foundations.
Can’t you just fill the bags with sand? Or stones? Or any loose aggregate?
Not if you want to sleep soundly. It is the solid compacted earth/clay brick that contributes to the structural strength of the building. Domes have been known to collapse because the aggregate inside was loose, and thus shifted as the build progressed.
In theory, for simple projects, if your earthbags are tough and hold, you could put anything in them. Certainly, the army have been building sandbag bunkers for years. But here’s the thing. Rip those bags open and you have...you got it. A mess. There are a number of ways the bags can lose their integrity: Polypropylene bags deteriorate fast in the sun. Jute bags tend to rot if used in damp climates. And if you happen to have mice attempt to move in – which take it from me if you live in the wild you will – then every rustle and scamper is a harbinger of doom. Mice love to shred things like sacks, polypropylene or otherwise. The only thing they can’t comfortably destroy seems to be metal.
The bottom line is, if you want your earthbag house to remain solid even if someone slashes the bags open, superadobe is the way to go.
So there you have it. In an earthbag.
Now let's hear your stories. Have you tried filling your bags with something else? Did it work?
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27/3/2017 12:49:41 pm
2/4/2017 12:13:48 pm
hi my name is steve. i notice i. these photos of you with the yellow bag on your head that the earthbag foundation is dug into the ground quite deeply. why is thst?
2/4/2017 01:18:26 pm
The rubble trench foundations were dug about 50 cm below the surface, not so deep. It might be the angle of the photo. The earth excavated from the foundations is piled up around the edge in the photo which may make it look deeper than it is. That earth was then used in the earthbags later on.
13/9/2017 02:51:08 pm
Hi, I've been reading up and studying the COB build method for several years. I now have some land and wish to build, I've had my head turned a little with your Earthbag projects and wanted to know a couple of differences.
13/9/2017 08:23:19 pm
Yes earthbag is faster as the dirt cures in the bags and you don't have to wait for one layer to dry before moving to the next. It's also far more resilient to earthquakes and flooding. Your foundation idea is sound in my opinion. Indeed I have seen projects with cob built atop earthbag stem walls just as you intend. To really make it water resistant you could fill the bags entirely with limecrete too. But earth stabilised with lime should be good enough. Yes the hard part about earthbag is the heavy lifting, and yes it can be a challenge to keep the walls straight :)
14/12/2017 05:02:56 pm
9/10/2021 04:58:27 am
# Great Post! Thank you for sharing useful information. We are also
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