[GSBN] Drainage within a plaster system

[Sarah Johnston]

  My intention would be to apply a 30mm clay/sand/straw plaster with  
this product embedded into/ onto the top of the plaster.  Or 20mm of  
lime/cement/ sand/ fibre plaster in place of the clay.  This would be  
the typical structural plaster and the thin plaster over the drainage  
mat would be to visually hide the mat and stop the wind from driving  
rain through the mat, thus adding to the typical plaster rather than  
weakening the system.

I am hoping this product would be robust enough to be able to hang the  
thin plaster on it with no wires creating any potential weakness in  
the weather tightness of the plaster system.  Due to the legal climate  
in NZ, the engineering is achieved by means other than the plaster  
system, cross bracing etc.  While the plaster is not considered to be  
structural, the system will be exposed to seismic activity due to the  
fact that Christchurch is still experiencing pretty good shakes on a  
regular basis.  (There have actually been over 11,000 shakes of 2.0 or  
more since the 'big one' three years ago)!  Do these engineering  
numbers support my hope???

  http://www.cirtex.co.nz/files/file/663/Duraflow+GNG+700+Series+Data+Sheet.pdf

As this drainage mat  is in addition to a fairly typical plaster  
system I am hoping the small amount of moisture which could  
potentially find its way through the outer plaster, across the  
drainage gap and into the typical plaster system would not be enough  
to become any issue with no typar type product.  I just need to find  
out how to get a sample big enough to test....

I look forward to reading through more of your "ranting and raving on  
this topic," John. and any other input would be great!

Sven Johnston
Sol Design Ltd
www.soldesign.co.nz


On 9/07/2013, at 9:04 AM, Frank Tettemer wrote:

> Hi Sven,
>
> While this flexible drainage plain may well provide the needed path  
> for intrusive water, and allow drainage from within the wall plaster,
> would it not also prevent bonding of the render to the straw bales  
> in the wall assembly?
>
> I'm imagining a 'brown' coat of plaster, worked into the exterior of  
> the bales, and the application of the Duraflow material to this  
> first plaster coat, while it is still wet and workable. Then the  
> second coat of plaster covers the Duraflow material, yes?
>
> Would this compromise the structural needs of the outer skin, in  
> it's function for structural engineering and seismic resiliency?
>
> Or, to say it all a different way:
> Wouldn't the use of the Duraflow weaken the strength of the wall  
> assembly?
>
> -- 
> Frank Tettemer
> Living Sol ~ Building and Design
> www.livingsol.com
> 613 756 3884
>
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Sarah Johnston
Sol Design, Ltd.
50A Connolly Street
Geraldine New Zealand
03 693 7369
sarahjohnston at ihug.co.nz