Cob: How thin is thick for footings?

[lyn behan]

I live in NSW, Australia and new to cob, our problem is the cost of footings 
- (the wider the wall the wider the footings). For a 1 storey house on 
reinforced concrete footings (mandatory requirement here) what is the 
minimum width of loadbearing wall?  Anyone in Australia with experience of 
getting council approval for a cob building?
We would also like a sod roof but not concrete. The problems we foresee are 
the effectiveness of the waterproofing membrane and if on wood the problem 
of termites and bushfires. Anyone out there who has had a wooden sod roof 
for more than 20 years?
Thanks
Lyn
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