[GSBN] Anyone ever try a cob/straw-clay hybrid?

[Tim Owen-Kennedy]

I would tend to agree with Paula and Chris, We've not done whole wall
assemblies but sections of wall similarly and it has been problematic. We
have done multi stories of bale with 6-12" of structural cob exterior, tied
to the bales with a light wattle in the center of the cob.

If you are considering a 26" overall assembly I would be tempted to build
one monolithic for ease of construction - cost savings and  balanced
drying; concentrating on a mix that maximizes insulation while barely
meeting your structural requirements (including factor of safety).
Insulative agregates and various types of fiber that are less mold
generating. I could imagine cobbing with three or more mixes that are
specified to be denser from the exterior to the interior and still
integrating the whole assembly as you went.

Seems to obvious for no one to have tried that before...Hope they or
someone they know are on this list.

Either way I'm inspired to do some testing

Tim


On Mon, Apr 29, 2013 at 10:32 AM, Paula Baker-Laporte <paula at econest.com>wrote:

> My concern would also be that the straw clay would only be able to dry
> from one side and that the cob would add to the moisture content for a long
> time...too long to dry the wall out safely.
> Building the straw clay wall first and then adding something like adobe to
> the interior could work.
>
> Paula
>
>
> On Mon, Apr 29, 2013 at 10:07 AM, Chris Magwood <chris at endeavourcentre.org
> > wrote:
>
>>  My concern would be drying for the straw/clay. We have a hard time
>> getting straw/clay to dry in our warm but humid summer. We count on a week
>> per inch of wall thickness, and that's with both sides of the wall exposed.
>> Sometimes we have to help things along with a fan on the interior because
>> the drying is slower in the still air. With one side of the straw/clay up
>> against cob (which may still be drying itself?) I would worry about the
>> straw/clay not drying out at all before it starts to get mushy in there.
>>
>> What about double wythe cob with a dry insulation in between?
>>
>> Chris
>>
>> On 13-04-29 11:38 AM, Bruce King wrote:
>>
>>
>>  A client in North Carolina (mixed climate, no earthquakes) wants to
>> build a large assembly structure on load-bearing cob, which doesn't
>> insulate too well.  He doesn't want to use bales with thick earthen
>> plaster, either.
>>
>>  So our idea was to build a wall that would look like this, from inside
>> to out:
>>
>>  14" -- 18" of load-bearing cob
>> 8" -- 12" of light straw-clay
>> lime plaster
>>
>>  Has anyone already done this, or heard of it?  Any reports of comments?
>>
>> Thank you!
>>
>>  Bruce King
>>
>>           (415) 987-7271
>> Skype: brucekingokok
>>          Twitter: @brucekinggreen
>>   http://www.housetalkgreen.com
>> http://bruce-king.com/
>>
>>
>>
>>
>>
>>
>>
>> _______________________________________________
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>>
>>
>> --
>> Chris Magwood
>> Director, Endeavour Centrewww.endeavourcentre.org
>>
>>
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>>
>
>
> --
> Paula Baker-Laporte FAIA,BBP
> Econest Architecture Inc.
> www.EcoNest.com
> paula at econest.com
> Phone: 541.488.9508
>
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>


-- 
Tim Owen-Kennedy, Owner
Vital Systems, natural building & design
P O Box 751, Ukiah, CA 95482
www.vitalsystems.net
888.859.6336
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