Cob: foundation ? why ?

[John Fordice]

Shannon & all,
To this list I feel we should add:
	6.- For seismic stability in earthquake country.  This is a very
important issue.  The inclusion of a reinforced concrete or masonry
foundation which is tied vertically (with either straps outside the wall
or rods inside the wall) to a rigid or flexible bond beam on top of the
wall has been tested and proven to assure the stability of adobe walled
structures when subjected to an earthquake with forces over three times
greater than that required by the building codes used in North America. 
In the absence of any predictable proof that cob buildings will survive
a severe earthquake, other than the limited examples from New Zealand, I
personally feel that this proven system of assuring earthquake survival
of an earthen building is a warranted precaution for anyone building
with cob where earthquakes may occur.

john fordice
maker of Cobbers Thumbs
TCCP  

"Shannon C. Dealy" wrote:

> 
> All of the reasons I can think of (there may be some I haven't thought of)
> to have a foundation under cob are as follows:
> 
>    1 - Prevent frost heave from shifting the building and damaging the
>        walls.
>    2 - Get the wall off the ground so that water from the ground
>        will not seep into the wall.
>    3 - Get the wall high enough off the ground so that rain splash will
>        not errode the wall.  What I am referring to here is raindrops
>        hitting the ground and splattering onto the wall.  In a couple of
>        buildings I have looked at, errosion from this is a significant
>        problem, where wind driven rain which directly impacts the walls
>        has little or no effect.
>    4 - Create a more stable base for the wall if the ground is not stable
>        enough to directly support it.
>    5 - To appease local building authorities so they will give you a
>        permit.
> 
> If these items do not apply to your application or are otherwise dealt
> with, I see no reason why you couldn't build it directly on the ground.
> Item three above might possibly be dealt with by embedding large flat
> rocks in the outside of the bottom of the wall, or just plastering the
> outside of the base of the wall on a regular basis.
> 
> Shannon C. Dealy      |               DeaTech Research Inc.
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