Understanding how to work with strawbale, rubble trench, timber frame and living roof

Hi there! Brainstorming here,
I am looking to build a natural round house on the top of a hill in Québec, Canada. I read Tony Wrench's Building a Low Impact Round House and I fell in love with his vision, although, in my case I would make some changes to add longevity to the house. I have been reading a lot about Ben Law' techniques and I love them as well, especially the Woodland House.

However, my design ideas are :
-Building a 30' diameter round house with natural materials
-Rubble trench foundation bellow frost line, with a drain at the bottom, a dry stone stem wall and insulation in the soil on the outside to prevent thermal bridging (not sure where to put it exactly)
-Round wood timber frame supporting structure with a reciprocal roof of 30 degree slope with secondary posts at mid span (see preliminary sketch) with or without the window in the middle of the roof which is a big leak hazard to me.
-Earthen floor with a hydronic radiant floor system
-Living roof if possible, although I am not sure how to insulate such a roof with natural materiel, thought I am willing to spend money on a well insulated and structurally sound roof.(it can get bellow -20 degrees celcius in winter so around R-50)
-The walls made from natural, local and low cost material such as in order of interest : straw bale, cordwood, hemcrete, cob.
-Protecting the walls with 3 ft. overhang roof.
-Lime plaster finish on the exterior.

If you agree that your building is an experiment and are therefore responsible from any problem sign here : Gabriel Babin

My main design concerns right now are :
-How to sit the house on solid foundation, both he timber frame structure and the straw bale walls?
-How to link the straw bale wall with the timber frame structure and the rubble trench foundation?
-How to insulate the exterior of the rubble trench to prevent thermal bridging?
-How to properly insulate and structure the living roof over the timber frame reciprocal roof and therefore prevent water leak for 50 years or more?

Any advice or suggestion would be greatly appreciated,
Dearly Gabriel

I would be very cautious about a 30' radius (!?), 30% slope, green roof in Quebec.  The radial roof is intriguing but I worry about snow load; the green roof will not shed snow well.  A 60' span without support is unlikely to meet code.  And I think the central 'eye' at the roof peak is part of the self-supporting design.

Hi Douglas Campbell, I made a mistake, it is not 30’ radius but diameter. Also I added secondary posts to better support the roof.