[Cob] great article???

[Shannon C. Dealy]

On Thu, 14 Jul 2005, Barbara Roemer wrote:

> I disagree with Ocean.  Earth buildings have a very spotty history in

The spotty history of earth buildings in seismic zones so far as I have 
seen and heard is strictly limited to mud brick / adobe style 
construction.  Monolithic cob type structures (which are not nearly as 
widely used) have generally done very well.

> seismic zones.  With particular waves, they are deadly.  To get any cob
> structures through CA code, or any other spot with seismic considerations,
> it will take some kind of cohesive exoskeleton or internal web, something
> much more continuous than the straw in cob.  It is true that adobe bricks
[snip]

I know of no information which would support this statement, at most it 
could be said that the above would be true if one wanted an easier way to 
get something "cob like" code approved in a seismic zone, but the same 
could be said of going post and beam with cob infill, these approaches are 
not unreasonable compromises, but are by no means a proven necessity 
for cob in a seismic zone.  To get proper cob code approved in a 
seismic zone will require the same thing that any other new material 
requires, good structural engineering data to design from, backed by
proper materials testing data.  The recent shake table tests at the 
University of British Columbia would appear to indicate that cob can be 
designed and constructed to meet seismic codes (without exoskeletons or 
internal webs), and the past history of some real world cob structures 
backs this up.  The question is not can it be done or can it meet code, 
but rather who will foot the bill for the necessary engineering data so it 
can be constructed correctly for a seismic zone.

Shannon C. Dealy      |               DeaTech Research Inc.
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