Largest round earthbag

Hi everyone. I am doing something I haven't seen done before and I want advice and opinions from everyone I can between now and when I start building. I have hired an architect and structural engineer to design the plans so that they will be approved by our local zoning department. My home will be 60' in diameter including the roof. I will be using a reciprocating roof and exposed beams. I am kind of throwing lots of ideas from yurts, earthbag homes and traditional houses together. We will be using 2"x6" lumber for the interior walls so we can have plumbing and electric ran without issue. There will be no electricity ran on the earthbag walls. I'm using solar exterior lights to eliminate the need for any electric on the exterior walls. We will be using a main post in the center to hold up the large roof. We will be using locally sourced lumber for the roof because of the size and length needed.
  Now for my main question. Is there anything you would change on my floorplan? If so, what and why? I'm also looking for insulation tips, and ideas for North Carolina's foothills. It can get up to 110°F during the summer days and as cold as 0°+/- during winter. I will be using passive solar to help with the electricity costs. My bags will be the 12" by 38" that will be filled in place so there won't be any heavy lifting. The roof will have over 2 foot overhang to help protect the walls. And we will be using stone to wrap the bottom 3 foot to help with the protection. My family members do concrete foundations, so they are helping us with digging of the plumbing lines and they will be helping us fill the bags and all that. I want to make sure that 2' deep is enough for my foundation. And what should be in the foundation trench. I know there should be gravel, but should there be sand or dirt to fill in the gaps? What size gravel should it be and what size gravel should be in the bottom bags? Also, has anyone done a natural bathtub? I want to dig out the tub and lines and not purchase a tub at all. I am imagining a tiny pool. I'm attaching an image of one I found. I really really want this but don't know how to make it happen. Any advice would be appreciated. I also want to do a shower with no actual materials. I will attach that image as well. Has anyone done this? I would appreciate any advice and information you can help me with.

You have many questions, and perhaps you need to break them down into the sequence the house will be built.
IE
- Foundations, size and type
- excavation, foundations plumbing, power, fresh air tubes
- earth bag details
etc, etc.
All the knowledge is about, and you need research to find out what questions you need to ask.

Hey Jennifer,

I agree with John. If you want more responses you might want to break up your questions into multiple posts. Here's my advice:

Jennifer Hartley wrote:Hi everyone. I am doing something I haven't seen done before and I want advice and opinions from everyone I can between now and when I start building. I have hired an architect and structural engineer to design the plans so that they will be approved by our local zoning department. My home will be 60' in diameter including the roof. I will be using a reciprocating roof and exposed beams. I am kind of throwing lots of ideas from yurts, earthbag homes and traditional houses together. We will be using 2"x6" lumber for the interior walls so we can have plumbing and electric ran without issue. There will be no electricity ran on the earthbag walls. I'm using solar exterior lights to eliminate the need for any electric on the exterior walls. We will be using a main post in the center to hold up the large roof. We will be using locally sourced lumber for the roof because of the size and length needed.
  Now for my main question. Is there anything you would change on my floorplan? If so, what and why?

I'm not a big fan of round structures. They tend to waste a lot of space and make the building process a lot more complicated especially at the scale you're talking about.  Reciprocating roofs are difficult to clad and insulate and with 30+ foot timbers you'll probably need a crane to install the roof. You'll also probably want some outside deck/porch space and/or a mud room. I would include that in that plans so it ties in with your roof. You're also going to need to run some electric in the earthbag walls to supply power to your interior spaces (e.g. the coffee station). Overall, at ~2500 square feet I think it's way to big for just a three bedroom/two bath and a huge endeavor to build with earthbag. If you're hiring help it will probably take two or three years and be very expensive. If you're planning to diy it with intermittent help from friends and family I think you'll end up hiring help or abandoning the projects. I would go smaller(~1000 sqft) and much smaller(200 -400 sqft) if you're diying it.

Jennifer Hartley wrote:I'm also looking for insulation tips, and ideas for North Carolina's foothills. It can get up to 110°F during the summer days and as cold as 0°+/- during winter. I will be using passive solar to help with the electricity costs.

Earthbags are best suited for areas with low humidity and large diurnal temperature shifts. If that's not you're environment a hybrid approach is often better. For example, building with straw bale or light clay straw on the east/ west and north(non-sunward) sides and using earthbags/cob and lots of glazing on your south(sunward) sides. Also, a well-insulated and possibly vented (in warmer climates) roof is critical. Also, just say no to western facing windows.

Jennifer Hartley wrote:My bags will be the 12" by 38" that will be filled in place so there won't be any heavy lifting.  

Look up hyperadobe. It's like earthbag but without the barbed wire. Also, your walls need to be a good 18" thick. 12" won't be enough thermal mass.

Jennifer Hartley wrote:The roof will have over 2 foot overhang to help protect the walls. And we will be using stone to wrap the bottom 3 foot to help with the protection. My family members do concrete foundations, so they are helping us with digging of the plumbing lines and they will be helping us fill the bags and all that. I want to make sure that 2' deep is enough for my foundation. And what should be in the foundation trench. I know there should be gravel, but should there be sand or dirt to fill in the gaps? What size gravel should it be and what size gravel should be in the bottom bags?

Get Earthbag Building by Kaki Hunter and Donald Kiffmeyer and Earthbag Building Guide by Owen Geiger. They have a lot of details about foundation work. Here's my video about building a rubble trench:

Hi, I have already paid quite a bit to have the plans made and don't want to change my plans. I can change bag size and look into superadobe, but I don't want to change the size or shape of my plan. We have around 20 people who will be helping and we will be hiring a roof company for the roof to be done correctly. I know it will be costly and am prepared to face that. As for the electric running into the exterior wall, my plan is to have the line come in at that coffee station and have the main breaker box at that spot. Or I may skip the coffee station if that plan doesn't work. Besides that I shouldn't need any power to an exterior wall. I will be using solar exterior lights to skip the need for power on the exterior.

Is there anything you would change on my floorplan?  

jennifer, but you asked for suggestions of changes!

John C Daley wrote:

Is there anything you would change on my floorplan?  

jennifer, but you asked for suggestions of changes!

Sorry, I meant like where things are or if I should add anything. I paid big bucks for a structural engineer to design the blueprint and can adjust it for another few. But I don't want to go smaller or do two stories. I want a home with good size rooms for my family. We have two boys who are homeschooled so they both need room for a desk and enough space for their toys. We know that this will take quite a while and have been planning for 3 years. We aren't scared of the project, just want any advice from others.