[Cob] cob oven cracks

[Shannon Dealy]

To quote Kiko Denzer (who has been building ovens and teaching oven 
building for over a decade if my memory is correct):

   "Some cracking is inevitable.  Most will not bea cause for concern.  All
   clays shrink as they dry; some more, some less.  Adding sand to your mix
   can minimize this effect . . ."

The degree of cracking if severe may be a cause for concern, but I have 
never seen, built, or heard of an oven that didn't crack.  Keep in mind 
that the inner shell of the oven is not significantly structural unlike 
the walls to a house.  If you are unsure about any details of building an 
earthen oven, I highly recommend Kiko Denzer's book "Build Your Own Earth 
Oven".  It can be ordered directly from the author's web site at:

    http://www.handprintpress.com/

In the interest of full disclosure, yes he is a friend of mine, and no I 
don't get anything for plugging his book.

FWIW.

Shannon C. Dealy      |               DeaTech Research Inc.
dealy at deatech.com     |          - Custom Software Development -
Phone: (800) 467-5820 |          - Natural Building Instruction -
    or: (541) 929-4089 |                  www.deatech.com