[GSBN] Deconstruction

Tracy Vogel tactileinteriors at hughes.net
Fri Jul 31 16:14:50 CDT 2009


Sounds like a great opportunity.  I love deconstruction...

And I agree with everyone else¹s input on what to document/test.  Do you
happen to know or are you able to get the information on original
application and the mixes?  As per Martin¹s inference, with that information
it might be possible to test the original plaster and compression etc and
then have a base line to compare the failure to.

Keep samples, lots of them.  Of course they will change relatively quickly
as well with drying and air flow and may be worth little shortly after

What are the parameters of the failure?  Was it localized or a full wall?
Was it only the top of the wall or all the way to the bottom?  Are you doing
localized repairs or a rebuild of the wall?  Would it be possible to
determine if the mold spores were from application or solely from the
failure?  How far did the mold impregnate the bales, and the plaster?  Is
the mold only on the straw/ fiber in the plaster?  Did the plaster have
methyl cellulose or other binding additives?  If it is an exterior (or
interior) wall was it sealed (with what) and therefore was it less
permeable?  Was there a fine finish coat that also may have lowered
permeability?  The plaster was up for 10 years right?  Is there anyway to
determine how much water, at what rate, over what amount of time flowed
through the wall?

How much do you think this may cost to assess?  I do think we could learn
something here that is valuable although my preference for CASBA funding
would be for full data sets that give us comparative analysis.  Data before
and after in a realistic setting.

I look forward to hearing more.

Tactile Interiors

On 7/31/09 9:17 AM, "martin hammer" <mfhammer at pacbell.net> wrote:

> On 7/30/09 11:32 AM, "Tim Owen-Kennedy" <timok33 at gmail.com> wrote:
>> I just started pulling apart an earth plastered straw bale wall that was
>> damaged due to roof failure and there is actually some significant mold.
>> Going to document as much as possible . . . but wanted to know if any of you
>> had any pet concepts or things you've always wanted to know about if you
>> could just tear into a wall . . .
>> Tim, if it¹s not too late:
>> In areas where you haven¹t yet pulled off plaster, I recommend you drill a
>> grid of holes in the plaster (one side only, maybe a 12² grid) in order to
>> insert a moisture meter probe, and take readings 2² from each plaster face
>> and in the center of the bale.  Then pull the plaster off each face and see
>> how the visible damage correlates with the moisture readings.
>> You could take the same readings after the plaster is pulled off, which would
>> be a lot easier, but soon after the plaster is off, the moisture content of
>> the straw (especially near the surface) might significantly change.  It may
>> already have changed since the water intrusion incident, but there¹s no way
>> to go back in time (yet) (or maybe there is, and there are people among us
>> who are from the future) (anyone on this list?).
>> Like Graeme I¹d like to see an assessment of the steel reinforcement after 10
>> years in a weather-exposed earth plaster.
>> Like Dave Arkin I¹m interested in saving plaster samples (ones that will
>> yield as large a cube as possible) for compression testing.  Although I
>> assume you don¹t have compression values from the time of application for
>> comparison.  Also, although it¹s worth testing samples 10 years after
>> application, I don¹t anticipate compression values much different than a
>> typical earth plaster tested 30 days after it was created.   I believe that
>> once an earth plaster (or adobe brick, etc.) is fully dry, it has reached its
>> maximum compressive strength.  It doesn¹t cure and become stronger over time
>> (even indefinitely) like materials with cement or lime binders.  It simply
>> dries.
>> If there¹s any additional costs associated with some of your ³research² work,
>> maybe CASBA could cover it?  With what has been discussed so far it doesn¹t
>> seem it would amount to much.
>> Thanks for requesting input, and I look forward to hearing what you discover.
>> Martin Hammer
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