[GSBN] Anyone ever try a cob/straw-clay hybrid?
Graeme North
graeme at ecodesign.co.nz
Wed May 1 08:45:02 UTC 2013
Hi Bruce
For what it is worth I have done a small trial wall with 150mm of dense cob laid up integrally with 150mm of low density cob on the exterior. It has worked just fine, and bonded well, and performed well, but yes, I agree with other comments that thicker walls may have issues of drying out to consider if you are using straw or other cellulose based fibre.
Graeme
Graeme North Architects
49 Matthew Rd, RD1, Warkworth NZ 0981
www.ecodesign.co.nz
Apr 30, 2013 08:54:16 AM, GSBN at sustainablesources.com wrote:
>Hello again. ;If you scroll down there are some pictures of this small project, "Terradoma". (http://www.gaiaarkitekter.no/tjome/ )
>Rolf ;
>29. apr. 2013 kl. 21:04 skrev asbn asbn at baubiologie.at>:
>
>Dear Rolf
>Great! Do you have any pictures from this project?I can`t find it on your homepage.
>I have seen Ianto Evans' cob-buildings and read the excellent book Building with Cob by ;Adam Weismann & Katy Bryce, who do this technique in (wet) Great Brittain.
> all the bestHerbert Gruber-----------------asbn - austrian strawbale network3720 Ravelsbach, Baierdorf 6www.baubiologie.at
>
>
>Am 29.04.2013 um 20:40 schrieb rolf:
>
>Hello. Here in Norway we built a small Cob-house with double Cob walls. ;We wanted to find ways to build high insulating walls with Cob - for cold climate. ;
>From inside; 8" Cob - 8" -dry insulation (Perlite) - 6" Cob. Using wooden connectors ;between Cob walls. (This is a small load-bearing structure).
>It worked fine.
>Rolf
> Siv.ark. Rolf JacobsenGaia Tjøme
>Ødekjærvei 653145 TjømeT; 48056168 / 33391900E; rolf at gaiaarkitekter.nowww.gaiaarkitekter.no/tjome ; ;
>
>29. apr. 2013 kl. 19:49 skrev Tim Owen-Kennedy timok33 at gmail.com>:
>
>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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>Econest Architecture Inc.
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