Cob Chimney?

[Michael Saunby]

This 17th century farmhouse has brick chimneys.  I suspect that prior to 
these it had stone.  There are a few stone chimneys on cob buildings here
and I expect they nearly all have flue liners.  With thatched buildings 
you need to be very careful about hot gases escaping into the roof, so 
on these old buildings chimneys get a lot of attention!

I keep seeing mention of straw free cob being used for flues and ovens.
Does cob really burn?  The original flues here are just ordinary cob
with an earth and cow hair plaster; it must have been ok for the first
hundred years or so.  I think I'd be more worried about cracks in the 
flue with the fire and poisoning risks.

-- 
Michael Saunby
Teachmore Farm, Jacobstowe, Okehampton, Devon, United Kingdom. EX20 3AJ