[Cob] NZ standards

[Graeme North]

Thanks for your comments Bernhard

Test bricks do behave a bit differently from walls, that is for sure -part of the fun. we have been looking at test results higher than I suggest too with good end results up so not quite sure yet what the end figure we use may be.  

How to even start to standardise the mushrooming effect  you describe, and that we experience, makes my head hurt.   (Better call it "bulging" so the moisture freaks do not get too worried)

The NZ Earth Building Standards revisions are underway but currently bogged down a bit in the bureaucracy as our dear neo-liberal government (I am being polite) is trying to turn Standards NZ into something that suits it ideology rather than help projects such as ours. But we are hopeful of good progress this coming year, if not this.

But we currently do use the current standards to argue successfully for cob.

I chair the working group for NZ E/B Standards so best to keep in touch through me.

Cheers

Graeme 

 
 
On 9/10/2014, at 7:03 AM, Bernhard Masterson <bernhard_masterson at hotmail.com> wrote:

> Hello Graeme,
> 
> .5% shrinkage seems reasonable, but I find that in practice I can build well with mixes that show shrinkage up to 1% in a test brick.  Building with higher shrinking cob works when one is building at a rate where the previous lift has had some time to dry and shrink but is still slightly plastic so the application of a new lift causes the previous to mushroom slightly.  The mushrooming action counters the shrinkage seen where drying cob can pull away from window bucks etc.  Would it make sense to address this in the New Zealand revision?
> 
> Also I am curious as to the status of the revision.  A couple of years ago I worked with some friends and turned in an application for load bearing cob walls to the city of Portland, Oregon (here in the U.S).  The city development office was interested but they were concerned about setting a less than ideal precedent and suggested we just wait to see what the NZ revision looked like.  Is there any sort of a working group that I could contact to stay up to date?
> 
> Thanks,
> 
> - Bernhard 
> 
> 
> Get under a sustainable lifestyle umbrella, the carbon is going to hit the fan.
> 
> ____________________________________http://www.bernhardmasterson.com
> Natural building instruction and consultation
> 
> Date: Wed, 8 Oct 2014 10:08:19 +1300
> From: Graeme North <graeme at ecodesign.co.nz>
> To: Feile Butler <feile at mudandwood.com>
> Cc: Coblist <coblist at deatech.com>, Pablo Loayza
> 	<info at naturallivingschool.com>
> Subject: Re: [Cob] Alternative Materials Justification
> Message-ID: <327DBA59-44BE-45E1-B4D5-986E023E13C7 at ecodesign.co.nz>
> Content-Type: text/plain; charset=iso-8859-1
>  
> A small correction to the NZ standards reference
>  
> These do not specifically refer to cob apart from an informative sections but have been used many times to design cob buildings by making bricks and testing them to NZS 4298 as for adobe, with an additional shrinkage test thrown in. Cob was partially referred to in this manner as we were having trouble determining a reliable pre-construction test limit for cob shrinkage, but will be fully included in the revision currently under way. We are currently thinking about 0.5% over a standard 600mm long shrinkage box but any ideas on this welcome too.  
>  
> cheers
>  
> Graeme 
> Graeme North Architects
> 49 Matthew Road
> RD1
> Warkworth 0981
> 
>