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Kiko Denzer on Art



Cob: indoor walls

Shannon C. Dealy dealy at deatech.com
Sun Jun 27 03:10:59 CDT 1999


On Sat, 26 Jun 1999, alexander neumann wrote:

> Hello everyone, 
> 
> Is there anyone who can confirm the prejudice that earthen indoor walls in
> modern airthíght houses make the indoor air too dry for humans and plants?
> And that the walls get wet over time?

Never heard of this one, but it doesn't make any sense.  Just as cob
moderates the temperature, it should also moderate the humidity inside the
house.  Cob walls never become completely dry, they stabilize at a
moisture level that is roughly equal to the average annual humidity.
As far as the walls getting wet over time, this is silly, the walls
start off extremely wet and it can take a year or more for a cob structure
to dry to a stable moisture level.  The only way for the moisture
level to start climbing again would be if you have a leak in the roof or
standing water at the base of the wall.

[SNIP]
> I can imagine that prejudice coming from old exterior walls  after
> "modernisation".

There have been serious moisture problems inside the walls of old earthen
buildings that have been treated with modern exterior sealants and
plasters.  These modern materials effectively seal the exterior of the
wall, so that moisture released into the interior of the building by the
inhabitants from breathing, cooking, washing, etc., cannot migrate out
through the walls, so it builds up over time in the wall near the exterior
seal, and eventually can reach levels which cause damage to the wall.


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