Why earthbag, why not cob?

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.

Cob requires clay. If you don't live in an area where clay naturally occurs, then you have to pay to bring it in, which pretty much defeats the purpose of building with locally available materials.

earthbags are considerably faster (think days, not months), much more moisture resistant (used for flood control), and don't require a long curing time (cob can literally take years to dry out).

But also, there's the mixing. Cob and adobe are very labor intensive, and mixing is hard work. Earthbags are hard work as well, but there is less work with that system.

You can also fill them with anything.

Water usage is a whole lot less with earthbags.

I don't think adobe or cob would be more ecologically healthy, necessarily. You can find scrap feed bags anywhere, so keeping those out of a landfill is not a bad idea.

There are probably more reasons, but those are the big ones.

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

I love cob.

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.

jeanna

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.

Yes, it is the labor-intensive issue...

Also, in some places (california) cob is not approved for earthquake codes, while earthbag is.