[Cob] great article???

[Shannon C. Dealy]

This was apparently intended for the coblist:

On Sat, 16 Jul 2005, Barbara Roemer wrote:

> In my enthusiasm for applying the method Copper pointed to, I made sweeping
> generalizations.  The B.C. testing is very encouraging.  I'm sure I spoke
> too broadly, and my frustration is not with cob as a material but with CA
> codes and the pace of the bureaucracy.  I don't have web sites, but my
> understanding is that given the varied types of seismic waves, one could not
> expect an earthen building by itself to stand up to them all.  It would be
> interesting to overlay a map of the seismic zones in the world on the areas
> of monolithic building traditions and see if there is failure, why it
> occurs, and if not, why.  I'd think it likely to be at the points of
> attachment: at the foundation and at the roof.
>
> What Shannon sez about new material approval is true.  My experience with
> building code is primarily in CA, and with various bale and straw/clay
> systems where I've seen tremendous concern over attachment, whether in
> load-bearing systems or non. (In AZ and NM, with little to no seismic
> activity, there is almost no code concern with the CA issues).  Where
> materials have been permitted, a lot of engineering has been required,
> including, in the case of light straw clay infill, virtually no credit for
> the infill or its structure, and not much credit for the posts and beam,
> meaning a lot of concrete and Hardy panels.  In California straw building,
> both load bearing and infill are permitted in some counties.  Most counties
> would permit load bearing with sufficient engineering, and the testing is
> on-going, so one could theoretically "buy" engineering (in the several
> thousands of dollars range, now, since a lot of expensive testing and
> engineering have been done).  The code concern with straw is over attachment
> of the wall system to the plates or roof bearing assembly.
>
> I generalized from what's worked with straw to what seems likely to work
> with cob (probably not a good idea) because of the attachment dilemma. If
> cob passes testing on the basis of its monolithic nature, isn't the point of
> failure still likely to be the plates?  I don't know, but I'd guess that
> it's roof cave-in that's responsible for more damage than wall-buckling to
> earthen buildings in seismic zones.  And if that's true, or if it's failure
> at the foundation as well (code concern is that a monolithic wall without
> attachment could slide off the foundation in seismic zones 3 & 4, a lot of
> California), then netting or pinning or something like the twining system
> Copper pointed to sounds like a gift.
>
> Barbara
>

Shannon C. Dealy      |               DeaTech Research Inc.
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