How to fill and lay earthbags conventionally
Normally, earthbags are filled with damp earth. The earth should have about 20-25% clay in it. If you are using bags rather than tubes, then you first fill the bottom of the bag and squash the damp dirt into the base and corners to create a nice square bottom. After that you fill the rest of the bag, and lay it on your wall. When all the bags in the row are laid, you tamp the entire layer with something heavy and flat. Tamping is key. It squashes the clayey dirt into a compacted, immovable layer. Eventually, when the house dries, that dirt becomes a solid clay brick.
The issue with handling damp earth
All of the above is pretty time consuming, and dragging bags full of damp dirt around is hard work. Under normal circumstances, and to prevent a hernia, once the wall gets higher you begin filling the bags on the wall itself. Again, this is pretty slow going, and can drive impatient types like me mad.
Is there another way?
I say, there’s always another way. :) Last year in my earthbag workshop in Turkey, we stumbled upon a brand new technique, altogether by accident, and it changed our earthbag world. You know how it is; someone makes a mistake, and it ends up being the best thing that happened.
The mistake was that a few volunteers threw a row of earthbags onto the wall without dampening the earth first. As I went round and prodded the bags, I could feel they were bone dry. Just a bunch of loose aggregate. You can read why you don’t want loose aggregate here.
Now...there is a common misconception that the polypropylene bags usually used for earthbagging aren’t breathable. This isn’t correct. They are definitely breathable and permeable. If they weren’t, your dirt wall would never dry out properly. So, knowing this, I decided to try and wet the bags on the wall (well, actually I decided someone else would wet the bags, but you know what I mean).
A kind helper grabbed a hose and gave the dry layer of bags a really good soaking. Then he grabbed the tamper and tamped the lot down. When I checked the bags, they were as good as the rest. The bags had absorbed the water, and the tamping had distributed the water evenly through the earthbag.
What’s the advantage of this?
The advantage of wetting the bags on the wall is that you don’t have to cart all that damp earth about, nor do you have to dampen the earth on the ground and mix it in (which is a bit of a bind in itself). It is a lot lot easier to work with the loose dirt, and easier to fill the sacks, too.
Step-by-step how to lay earthbags using the new technique:
1. Make sure your clay is distributed evenly into your dirt.
2. Fill your earthbags with dry soil.
3. Lay them on the wall.
4. Take a hose and give the whole layer a thorough wetting. Make sure all the bags are well dampened.
5. If you’re using individual bags, go around and check the corners of the bags are nice and tight, and not sticking out. Reshape and regusset them where necessary.
6. Tamp the whole layer.
Note: This technique only works by dampening one layer of bags at a time. Don’t throw a whole house up and then think you can squirt a hose on it. It won’t work.
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