[GSBN] Drainage within a plaster system
Sarah Johnston
sarahjohnston at ihug.co.nz
Sat Jul 13 18:52:43 UTC 2013
Thank you for your thoughts John and Ian.
I believe you are both correct. I did fail to mention that it is my
intention to structurally connect the exterior plaster to the
perimeter beam at the top of the wall with a batten fixed through the
entire plaster and drainage plane system. Once the peeling effect is
minimized at the top of the wall, the 'normal' gravitational loading
will be in the 'machine direction' of the fabric. My gut feeling is
that this fabric would work very well in this orientation. The big
question to me is the movement of mother earth. How much out of plane
movement can this withstand?? I will let everyone know if/ when :) I
get successful text results.
Give it go.... Sven
On 11/07/2013, at 12:56 PM, Ian Redfern wrote:
> Good afternoon John, Sven and All,
>
> I like the concept of a thin drainage plane behind a rain screen
> which this product will provide
> HOWEVER secudrain is designed for horizontal loading where the
> product resists crushing forces yet maintains in plane drainage e.g.
> Interlayers of roads or landfills.
> The apparent confusion is the pull apart strength (tensile strength)
> along and across the sheet, not the tear off or SHEAR effect of
> vertical loads where the rain screen plaster coats hang onto the
> outer skin of the cloth - as John and found this stuff will tear
> apart !
>
> So
>
> My suggestion is to pin this over the (structural) scratch coat that
> is direct plastered onto the straw, then overlay this with cintoflex
> D and lay up the two or three coat lime plaster rain screen and
> finish this off with a lime wash
> The rain screen will be supported by the cintoflex (refer Bruce
> Kings book for loadings and fixing tests) along the soffit line, and
> will need additional fastening along the bottom plate above the J
> flashing. The cintoflex will probably need some "anti billowing"
> fixings of say roberto pins into the bales at up to 400 centers
> across the face of the wall
>
> ian
>
> www.adobesouth.co.nz
> Ian Redfern
> Adobe South
> A: 5 Lancewood Rise, Onerahi, Whangarei
> P: 09 436 4040 M: 027 490 2324
> E: ian at adobesouth.co.nz
>
> From: John Swearingen <jswearingen at skillful-means.com>
> Reply-To: Global Straw Building Network <GSBN at sustainablesources.com>
> Date: Thursday, July 11, 2013 9:23 AM
> To: Global Straw Building Network <GSBN at sustainablesources.com>
> Subject: Re: [GSBN] Drainage within a plaster system
>
> Sven...are you confusing "machine direction"? Doesn't it refer to
> tension in the plane of the material. The sandwich materials like
> this that I've seen can all be pulled apart by hand (we do it
> regularly), and that doesn't seem strong enough for a major seismic
> event...
>
> John "Cross Machine" Swearingen
>
>
>
> On Wed, Jul 10, 2013 at 2:05 PM, Sarah Johnston <sarahjohnston at ihug.co.nz
> > wrote:
>> Thank you all for your thoughts...
>>
>> The plaster keys into the geotextile and the geotextile is well
>> bonded to the mat. The specs say that the tensile strength
>> (Machine Direction) is 7.5 KN/M for the mat with the geotextile
>> bonded to both sides. I do not know what this number equates to in
>> potential thickness of plaster hanging on it.... Any thoughts
>> anyone??
>>
>> The secuDrain http://www.cirtex.co.nz/files/file/375/Std+Secudrain+131+C+WD+401+131+C%2C+Rev+5_en.pdf
>> does seem like it should be better and the specs suggest the
>> tensile strength is twice as good as the duraflow. The reason I
>> have not been considering the secudrain over the duraflow is that
>> the samples I have do not seem to reflect the data on the
>> website. The duraflow was far more difficult to pull apart.. I
>> guess it all comes back to trying them both on a wall, then test
>> them.
>>
>> If we have living green walls like John suggests... Would that
>> make us 'greenies'?
>>
>> Sven
>>
>> On 11/07/2013, at 2:47 AM, John Swearingen wrote:
>>
>>> The drainage mat is very thin, and I'm not understanding how you
>>> plan to "embed" the mat to the base coat, and then bond the
>>> exterior plaster to the geotextile, both securely enough to keep
>>> the plaster layer from falling off in a good shake? BTW, I would
>>> consider using their "SecuDrain" rather than Duraflow especially
>>> if you can get it with geotextile on one side only.
>>>
>>> Have you thought of wrapping the building in something like
>>> DuraGreen? Never mind the plaster, grow plants.
>>>
>>> John
>>>
>>>
>>> On Wed, Jul 10, 2013 at 2:33 AM, Sarah Johnston <sarahjohnston at ihug.co.nz
>>> > 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
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>>
>>
>>
>>
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>
>
>
> --
> John Swearingen
> Skillful Means Design & Construction
> 2550 9th Street Suite 209A
> Berkeley, CA 94710
> 510.849.1800 phone
> 510.849.1900 fax
>
> Web Site: http://www.skillful-means.com
> Blog: https://skillfulmeansdesign.wordpress.com
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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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