Berming earth-tubes like an earthship

Long time lurker first time poster

For the past 4 years I have immersed myself in earthbag/ship construction and have a very good grip on it.

My question is berming earthbags. If
You laid out the long tubes just like the big "u" shaped earthships is it
Possible to berm them?

Would you have to Cob /plaster before berming the backs?
I am closing in on my land in BC, and plan on building an earthship but from eaethbags completely as I think it's a much better way to build then pounding tires. I feel the whole tire thing is old as tires are mass recycled these days and I really enjoy earthbags.

I would like to incorporate the systems in an earthship except with aqua ponics rather than the earthship model.

I understand rubble trenching, filling first few rows with gravel etc, my big concern is the berming and if the bags should be set back every row by an inch or so, resting against the berm???

Wanted to add on my thoughts on berming the bags:

Staggered slightly going back towards the berm with rebar pounded through once at top level.

Was planning on adding thermal wrap etc as per Earthship design. I have acces to front end loader with an Earthbag auger attachment to REALLY speed up the walls.

But where I'm scratching my head is the back end of the bags in the berm, I'm guessing they would deteriorate after time in the berm without cobbing or sealing of some sort??

Hey Sean!
Sorry about the delayed reply. Surprised no earthbaggers jumped at the opportunity to recruit an earthen builder away from the dark side. EB is a much more efficient way to lay down and plaster some rammed earth compared to a tire form. However, tire walls are wider than 50lb bag walls, therefore structurally you'll appreciate incorporating a technique other than straight vertical spans seen in traditional tire work of the earthship "U's".

1. http://www.earthbagbuilding.com/faqs.htm familiarize yourself with these topics, and read the earthbag book by kaki Hunter/Donald kiffmeyer. These spell out ways to address the structural capabilities of bagwork in regard to butressing, long vertical walls, and retaining a berm.
Some options are battering (staggering) back into the berm - very effective but aesthetically strange to me for a main living space unless you were to build that wall in shelving or something. Another option would be posts set inside to the (preferably interior room side) bag wall - these can tie into rafters as well as simplify attaching joists, interior walls, shelving, cabinetry, etc. Another popular option is buttressing. A final option is to round your north walls out into the berm since structurally "round is sound" especially when berming or burying.this can look and function great as long as you're willing to accommodate some curved walls in your floor plan. My cool pantry is buried using this last method.

2. Polypropylene bags supposedly only degrade under UV and harsh pHs. Therefore you don't need to plaster the backside of the bags. If you fill your bags with appropriate earthen fill (No pure sand fill in this application) what if the bags degraded in 100-200 years? I don't see how that would affect anything. In Brazil it is common to burn off the bags. Since your whole build is buried in a wet environment I would recommend a layer of 6 mil against the bagwork, Even if you are laying another on your thermal wrap. Cheap insurance.

3. Consider how you will terminate the southern end of your interior walls. Post at end tied into rafter, buttress at end, or my favorite a short perpendicular wall buttressing your interior wall that is large enough to provide a nook as well as place thermal mass where is counts the most - in direct sunlight.

4.Take a video of that earthbag auger in action. Slightly jealous.

5. Is that your real last name?

-Earthbag chris