what are my options for a fast cold earth wall?

I need to get a small earth wall up fast. It will be the back wall of a solar greenhouse. If I can get this wall and some of the wooden framework up and covered with building plastic, I will be able to work on the glazing and interior all winter. Colorado winters can be very cold and snowy, but only for a few days here and there. Most days it gets up above forty degrees, and snow rarely lasts more then a week on the ground.

So, I need an earth wall which can take a some light frosts and go up fast. What would be best? Earthbag, cob, slipform rammed earth, or slipform poured stabilized adobe? This wall also needs to be able to take greenhouse conditions (under a layer of lime plaster.)

Earthbag would need buttresses. Rammed earth needs forms. Cob can go slow and mold in a damp cold period. I am not sure on the process for slipform adobe.

CEBs are out of the question due to lack of money for a machine.

Gilbert Fritz wrote:
Earthbag would need buttresses. Rammed earth needs forms. Cob can go slow and mold in a damp cold period. I am not sure on the process for slipform adobe.

All of these techniques will behave about the same in terms of the need for buttresses, to my knowledge. That is, for the same thickness and taper, earthbags aren't going to need buttressing and adobes not need it. So speed is your real issue.

It seems like the carpentry involved in formwork might be intimidating you- is that an accurate impression?

I can't claim to have built with all four of the styles you mentioned, but I gather that cob is the slowest. Making adobes now, in the fourth week of September, and waiting a couple weeks for them to dry before you build with them... that's probably too slow for you too.

So earthbag or rammed earth? I hear that earthbag is faster. Have you sourced some bags?