Cob: wall cracks

[Shannon C. Dealy]

On Thu, 2 Nov 2000, Roxboro Yurt wrote:

> I have searched the archives and can't seem to find
> any info on wall cracking.  My cob walls (about 7 ft
> high at this point) are starting to get little
> fractures at the bottom in some places where the cob
> is almost totally dry. Usually about three to four
> inches long and very very narrow. They don't look too
> serious, can anyone tell if this is par for the course
> or something I should be worried about?

Small hairline cracks are quite common in cob and generally are nothing to
be concerned about.  Usually cracking is caused by shrinkage as the cob
dries, though it can also be caused by uneven settling of the building or 
excessive point loads on the walls as well.  While a really good high sand
and fiber cob mix made with a minimal amount of water can greatly reduce
the amount of cracking, they will not eliminate it entirely.

Shannon C. Dealy      |               DeaTech Research Inc.
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