[Cob] Exterior finishes for insulated cob

[Sky Orndoff]

Hi!

I'm thinking about making a cob building in Montana.  I'm thinking cob because I 
like the sculpting and the thermal mass.  Because it will be in Montana, and 
because I'm an energy auditor who believes in insulation more than thermal mass, 
I'm interested in insulating it thickly, probably with a shredded cellulose.  I 
think I'll use wood 1.5"x12"s to frame a cellulose wall onto the outside of the 
cob. We have a lot of dead and dying trees that are being logged already and can 
be delivered to a friends sawmill for free.  I'll probably put cellulose between 
the boards about 24" OC.  What I would like advice on is an appropriate exterior 
cladding or siding or exterior coating for the celulose insulated wall.  I want 
to do a floorplan with curved walls, keeping the walls vertical, so the cladding 
will have to be flexible in one direction.  What would people advise for this?  
Something with sand-clay?  Some type of product?  Suggestions for other 
solutions than the one I'm thinking of now?

Thanks for your consideration,

JS Orndoff