[GSBN] Drainage within a plaster system

[Derek Stearns Roff]

Your approach seems promising to me, Sven.  The final thin plaster layer has to be thick enough to stand up to the physical abuse that the outside plaster surface will receive.  I don't think that is a problem, it just sets a minimum thickness boundary.  Another plus of this approach is that the surface layer will be easier to inspect, repair, or even replace than a monolithic three-coat plaster system.

Derek

On Jul 10, 2013, at 3:33 AM, Sarah Johnston wrote:

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<http://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




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Derek Roff
derek at unm.edu<mailto:derek at unm.edu>


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