[Cob] hybrid bales bags

[Jilly]

Oh I DO have the book, The Hand-Sculpted House. 
That is where I first was given the impression to use straw-bale or hybrid system. 
I understand how to use straw bales for a small area. But to create the entire north wall or large span, I was not sure. Also, was not sure if it was superior to earth bags. 
If I make the north wall all straw bale, load bearing (is that really safe?) won't it compress when I add the roof? So how much higher should the top of the bales be in compared to the cob? Precompresed bales? 

Also I was questioning using all straw bales, then covering with earthen plaster / cob.. or earthen bags and doing the same. Wondering about strength, ease of building, insulation, cost, time in building, ect. 

jilly