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Re: GSBN:plaster and straw question



Rene
I think that the main issue is :
Why did the stucco (render) crack?
Was it due to soil movement
Was it due to insufficient bale compression
Was it due to delamination of the render off the bales.

Then I totally agree with you regarding overhangs and good detailing.

You know the old adage for moisture not getting into buildings:
They must wear good rubber boots (Damp proof course), good raincoat (good
render and detailing) and wear a good hat (overhang).
I'd like to hear more from Graeme from New Zealand as they have huge
problems with moisture.

Bohdan
----- Original Message -----
From: "Paul Olivier" xpolivier@...
To: GSBN@...
Cc: rene.dalmeijer@...
Sent: Wednesday, July 05, 2006 10:29 PM
Subject: Re: GSBN:plaster and straw question


>From: Rene Dalmeijer rene.dalmeijer@...
To: "Paul Olivier" xpolivier@...
Subject: Re: GSBN:plaster and straw question
Date: Wed, 5 Jul 2006 11:59:09 +0200

Paul,

I would like to react directly. Based on my current knowledge.

Basically straw is susceptible to mold growth if moisture levels are above
20%. A good SB design should ensure that these levels occur only rarely
and
for short spells only thus ensuring a long life-span.

Measures to be taken:
- sufficient overhangs

Does this mean that all walls have to be protected by porches or
overhangs?

- no cracks in the interior or exterior plaster basically the plaster
surface should be airtight.

Can this be achieved with reasonable certainty?

This was a very big problem in the two SB structures I put up in Texas.
Cracks in the external stucco coatings appeared.
This was a cementatious stucco applied in three layers by a professional.
At the time I availed myself of the best expertise in SB construction,
and I followed the best advice I could get.

- the plaster should be moisture permeable therefore the preference for
earth or lime plasters

Moisture permeability was strongly advised, but earth or lime plasters
were not underlined at the time as being critical.
Can earth or lime plasters hold up, for example, in a hot and humid
south Louisiana climate, where storms and hurricanes often pound the
wall of a house (unprotectd by porches) with horizontally falling rain?
Have we not reached a fundamental contraint of the
strawbale method? Are there places it should not go?

- detailing of all interfaces should take account of the above and also
avoid cold bridges leading to internal condensation

This makes sense.

If the above measures are taken and sufficient maintenance is carried out
a
SB wall will last for ever in as far as I know nearly all climate zones.

This statement needs more clarification in view of the questions
posed above.

Thanks so much. I truly appreciate your direct response to my
previous email.

Paul Olivier
ESR International LLC
(now living in Vietnam)

Tel 1-214-306-8746
Tel 1-337-447-4124
<a  target="_blank" href="http://www.esrint.com/";>http://www.esrint.com/</a>









Thanks.

Paul Olivier
ESR International LLC

Tel 1-214-306-8746
Tel 1-337-447-4124
<a  target="_blank" href="http://www.esrint.com/";>http://www.esrint.com/</a>





From: Rene Dalmeijer rene.dalmeijer@...
To: "Paul Olivier" xpolivier@...
Subject: Re: GSBN:plaster and straw question
Date: Wed, 5 Jul 2006 11:59:09 +0200

Paul,

I would like to react directly. Based on my current knowledge.

Basically straw is susceptible to mold growth if moisture levels are above
20%. A good SB design should ensure that these levels occur only rarely
and
for short spells only thus ensuring a long life-span.

Measures to be taken:
- sufficient overhangs

Does this mean that all walls have to be covered by porches or overhangs?

- no cracks in the interior or exterior plaster basically the plaster
surface should be airtight

This was a very big problem in the two SB structures I put up In Texas.
Cracks in the external stucco appeared.

At the time I tried to avail myself of the best expertise in SB
construction,
and to follow the best advice I could get.

- the plaster should be moisture permeable therefore the preference for
earth or lime plasters
- detailing of all interfaces should take account of the above and also
avoid cold bridges leading to internal condensation

If the above measures are taken and sufficient maintenance is carried out
a
SB wall will last for ever in as far as I know nearly all climate zones.

Rene
On Jul 3, 2006, at 08:10, Paul Olivier wrote:

But how does one solve unequivocally the problem of strawbale moisture
penetration,
especially in a moist and humid climate? Is the moisture penetration that
we are so concerned about simply due to faulty construction techniques?