I've been reading alot about earth bag, and was simply wondering why people even bother useing the earthbag system. It seems like cob or adobe is just as striong, but more ecologicaly healthy? Or is there something I've missed about earthbag that cob doesn't offer.
I am aesthetically very attracted to cob construction, though my site (and this area in general) are very sandy, so I'd have to have it brought in from some miles away. So recently I've been thinking about earthbag...though neither earthbag OR cob alone would do very well in Michigan's cold winter climate without supplemental insulation. For this reason I'm interested in both strawbale construction and underground/bermed houses with a good passive solar design, in tandem w/ an efficient (masonry?) stove that captures a lot of the heat into some sort of thermal mass and radiates it slowly. PJ
It seems like the big difference between cob/earthbag/adobe is what you have available for resources and labor and what sort of design you want. They are all labor-intensive techniques that you can use various labor saving methods.
For me adobe and CEB blocks are readily available at low cost - so I'm going that route. Also, I currently live in an oval house and find it somewhat annoying from a space efficiency standpoint. So the curves that are easy with cob or earthbag are lost on me. Give me recti-linear construction with rounded edges any day.
But you must build a roof on top of the cob building, unless you are in a desert.
The earthbags just continue to spiral up to the point peak and that is the roof.
I did see rather a lot of dome shaped earthbag buildings on the earthbag site. I also noticed that any of the pictures of the dome shaped earthbag homes were as first built. That is empty without furniture. Except for one which had a failed or at least failing roof. I did find a number of earthbag homes that looked like they had been lived in for some time, but they all had a "real" roof. I also read the FAQs through. They state that the dome roof is not for wet climates... so the earthbag dome is ok for a desert, but not where it rains, same as cob. BTW, the earthbag dome is also not recommended to be buried. It is ok to berm against the walls so long as there is a vapor barrier on the outside of it. (at least all of the plans I found had it) I think sharp gravel in chicken wire might be good for a bermed wall.
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