[Cob] hybrid bags

[Jilly]

I have the books mentioned, regarding earth bags in a foundation setting. I was questioning the use of them as a wall, the north wall. 

http://www.calearth.org/apprent.htm

Or even using them, then cob over the top, for ease of building as well as the fact they are permitted to build in areas. 

I only question the roof, as it is vaulted, what roof material to use, as the cob needs to be protected and I am building in a wetter area - not dry arid, as where this link is located. 

jilly