[Cob] Moisture, mold, and walls

[Joseph R Dupont]

legionairs disease was cased not by the air conditioning but hot water ..
old hot water .. never flushed
in the pipes.. breading for decades.. hot but not hot enough to kill the
bacteria.

On Sun, 25 Jul 2004 11:54:57 -0700 (PDT) "Shannon C. Dealy"
<dealy at deatech.com> writes:
> On Sun, 25 Jul 2004, GlobalCirclenet wrote:
> 
> [snip]
> > mold problem it's because the house isn't properly sealed against 
> moisture
> > where it should be sealed, and you have to move out. Then it costs 
> a
> [snip]
> 
> This isn't correct, while a lack of seal against moisture could 
> cause mold
> problems, it is in fact buildings that are to tightly sealed which 
> are the
> ones making it into the news and are the source of the reports on 
> "sick
> building syndrome".  I have looked at the facts surrounding quite a 
> few of
> these, and in each case, the wall system sealed the house so tightly 
> that
> moisture could not escape, and since living is an inherently 
> moisture
> producing activity, moisture levels shot up in variouss places in 
> the
> walls and interiors of these buildings, ultimately reaching the 
> point
> which would support mold growth.  Cracks in interior plasters on 
> bales
> isn't going to create a mold problem in and of itself (though in 
> wet
> climates exterior cracks could), it also requires a source of 
> sufficient
> moisture concentrating in that area, so cracks in a bale plaster job 
> in a
> bathroom is far more of a concern than plaster cracks in a living 
> room.
> The problem is not that moisture gets into walls, regardless of 
> what
> they are made of (bales, cob, wood frame, concrete, steel, etc.), IT 
> WILL,
> the problem is does the wall system allow the moisture to escape 
> from any
> and all areas on average as fast as it infiltrates.  It is important 
> to
> note here that by escape, I mean pass through the wall, since it 
> must be
> able to reach the side of the wall with lower humidity, or it 
> hasn't
> escaped.  Cracks in interior plasters on bale walls allow more 
> direct
> contact with the interior air of the building, but this is a 
> relatively
> minor issue unless that air has extremely high relative humidity 
> (such as
> a bathroom or possibly kitchen), in which case, even a straight 
> earthen
> plaster over the wall may have issues as well, and may not be 
> sufficient
> to protect the bales behind them.  Moisture is going to get into the 
> wall
> through even a perfect plaster job, it is even going to condense in 
> the
> wall (bales or otherwise), but as long as it is able to migrate out
> reasonably quickly by wicking, air migration, or other means, mold 
> is not
> going to be a problem.
> 
> How moisture gets into and out of walls is one of the most 
> important
> lessons of modern building, because a large percentage of building
> officials, architects, and building material manufacturers do not
> understand this most basic of problems, and in the interest of 
> higher
> insulation / energy efficiency, reduced maintenance, etc., make the
> absolutely worst possible design choices.  Some of them have learned 
> from
> these mistakes (based in the recent increase in articles regarding
> moisture and wall breathability), many are still clueless.
> 
> [snip]
> > will mold faster than wood. Cob or other earthen material will not 
> mold.
> [snip]
> 
> It might be more correct to say that the interior of cob or earthen
> materials will not mold (where the interior of straw bales 
> definitely
> will mold), the straw sticking out of cob as well as the organic 
> matter in
> the soil the cob was made with will mold on it's surface, even after 
> the
> cob has dried if the relative humidity is high enough (and yes, I do 
> know
> from personal experience -- I sometimes wonder if I don't experiment 
> far
> to much :-)  Mold will actually grow on anything, since even the 
> dust in
> the air has sufficient organic matter to support mold, all it has to 
> do is
> settle somewhere moist, this is how galvanized steel ducting in 
> houses and
> office building is able to support the growth of mold.
> 
> 
> Shannon C. Dealy      |               DeaTech Research Inc.
> dealy at deatech.com     |          - Custom Software Development -
>                       |    Embedded Systems, Real-time, Device 
> Drivers
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> 
> 
> 
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