Cob House in Joshua Tree, CA questions

Hey folks!
I am new to Cob building, and could not be more psyched to start the journey. I will soon be purcasing some rural land in Joshua Tree, CA, and would like to build a 625 square  foot cob home out there. I am still a ways off from starting any kind of building (Probably next summer), but am scheming and planning my build every second. The foundation will certainly be the most difficult part, as I do not have much concrete experience.

That brings up my first question: Has anyone laid down a foundation for a 625 sqaure foot cob home themselves with success? Any tips?

Second question concerning the cob itself. From the Morongo Basin soil analysis done by the DOA it seems like the soil/earth around where I want to build is only 1-8% clay. Is there anyway that would work for cob? Am I going to have to source my clay from somewhere else? Lincoln clay? If so, any idea how much I would need for 625 square feet, single story, 20" thick walls?

Third question: How feasible is it to build "under the radar"? I would rather not spend a fortune and time on permiting. Anyone had good success building under the radar in rural areas? I don't need the governments hands in my home.

Thanks folks! Can't wait to get this started!

Taylor Olsooon wrote:Hey folks!
I am new to Cob building, and could not be more psyched to start the journey. I will soon be purcasing some rural land in Joshua Tree, CA, and would like to build a 625 square  foot cob home out there. I am still a ways off from starting any kind of building (Probably next summer), but am scheming and planning my build every second. The foundation will certainly be the most difficult part, as I do not have much concrete experience.

That brings up my first question: Has anyone laid down a foundation for a 625 sqaure foot cob home themselves with success? Any tips?

Second question concerning the cob itself. From the Morongo Basin soil analysis done by the DOA it seems like the soil/earth around where I want to build is only 1-8% clay. Is there anyway that would work for cob? Am I going to have to source my clay from somewhere else? Lincoln clay? If so, any idea how much I would need for 625 square feet, single story, 20" thick walls?

Third question: How feasible is it to build "under the radar"? I would rather not spend a fortune and time on permiting. Anyone had good success building under the radar in rural areas? I don't need the governments hands in my home.

Thanks folks! Can't wait to get this started!

I have a friend who may be in Joshua Tree if you are interested in company/help.. and I have always done as much as possible “under the radar”. Play it smart, but this is your life.. and falling prey to the mental trap of “needing permission” to live is a choice! As far as the soil composition, make a test adobe brick. Best of luck in all that you do..

I have built 1150 sq ft compressed earth block house.
I assembled all foundation reinforcing myself with a help of a laborer. I made the forms. During the pour I got more help. I can share reinforcing detail with you (designed by an engineer). Working with rebars is simple but will squeeze a lot of sweat and will generate major body pain - you just need a manual bender. In case of more complicated bends it's good to have a bender that works in horizontal plane. I ordered all stirrups - I would waste too much time bending them.

For cob mix you will rather need to amend your soil with clay.
For just outside walls of this thickness you will need around 34 m3 of material. Assuming that you already have 5% clay and want to add 20% then you would need around 7 m3 of clay, so it would be a truckload (short dump truck). You will have to do some research to source clay in large amounts. I bought it by a truckload from a local nursery - around 10 tons, total $900 (clay + delivery) in 2018.  

Stay under the radar, but build it right.

Not sure if you are aware, but California quietly adopted monolithic adobe aka cob into California building Code

https://codes.iccsafe.org/content/IRC2021P1/appendix-au-cob-construction-monolithic-adobe-