Cob Chimney?

[Mike Carter]

Has anyone out there built a Cob chimney (above roofline)?

Our flue is made out of Cob (no straw, high sand mix liner) and is built
into the wall.  BUT, we need to extend a chimney up above the roof level.
This means that there will be no "hat" to speak of over the Cob on the
chimney if we use Cob for the chimney wall (in addition to the flue liner).

1)  Should we do the exposed (7' or so) part of the chimney with Cob or use
something else, like brick?

2)  If we use Cob, can we use a water-resistant coating (like stucco) since
the Cob can breath from the inside of the flue pipes (there are 2 of these,
8" in diameter).  Or should we just use a very thick plaster and plan of
maintaining the chimney every couple of years?

Mike Carter
cobcrew at sprynet.com
Austin, TX    USA