Cob: RE: breathing cob walls

Mon May 15 13:37:42 CDT 2000

In the same vein, how does applying tile to a cob wall work?  I mean, say I
wanted to put up tiles in a bathing area, wouldn't putting up glazed tiles
with mortar seal the wall, and wouldn't that be bad?  Or could you just
embed the tiles in the cob?  I also had a friend who was thinking of using
tile to mosaic the outside of a cob building...  Would this cause breathing
problems?

-----Original Message-----
From: Bob [mailto:owl at steadi.org]
Sent: Friday, May 12, 2000 11:57 PM
To: coblist at deatech.com
Subject: Cob: breathing cob walls

I'm glad someone brought up the need for cob walls to breathe.  In New
Mexico the restorers had the bright idea of coating the outside of a very
old adobe church with mortar to protect it from the weather etc.  It almost
destroyed it, however.  Moisture that is in most all air entered the wall
from the inside and got trapped just under the mortar. Over the years it
softened the clay in the raw (unfired)  bricks.  Watertight sealants will
gradually soften the clay under them.  It may not show in a year but it will
over time. 
 This church was in a quite dry climate near Santa Fe, New Mexico.  If you
would like more details I will look up the recent Smithsonian article and
put the page and issue on this net.

IT IS DANGEROUS TO TRY TO SEAL AN ADOBE OR COB WALL.  THEY NEED TO BREATHE.

Potassium silicate, I believe is a sealants that can cause this gradual
deterioration of unfired clay walls.    You may be undermining your
building.  Just what potassium silicate would do to garden walls is another
question.  Perhaps they would make the wall last longer than an unprotected
rain drenched wall.  Much better are the ideas of putting a roof on the wall
with an overhang and putting stones in it that stick out.  Even terracotta
(cooked earth) tiles that are not glazed, just low fired, would be good
protection even though they are a little porous.  Most of the rain would run
off.  If the wall breathed the little moisture that went through into the
wall would likely work its way to the sides and evaporate.

What is important to remember is that even inanimate things are dynamic,
changing slowly or fast depending on the climate.  In the Egyptian desert
they can last for thousands of years but there are few places  that dry in
the world.  Even the ancient hieroglyphics thousands of years old, when
inclosed and viewed by too many  tourists can be destroyed by the moisture
evaporating from their bodies.  So we have to bend with the weather and the
impacts of changing climates and recognize that every move we make impacts
the world of future generations.  Acid rain, thanks to our  blind use of
technology, is decaying even stone monuments that lasted thousands of years.
The automobiles in Athens are destroying the ancient Athenian buildings, for
example.

Americans look for quick fixes.  When they are efforts to short cut natural
processes they always backfire.  Cob is great because it is mostly a product
of nature and when properly used and cared for can last for ages.  Tune into
it and it will give you a singing house.  Try to defeat the natural process
and they will let you down, or let the roof down on your heads.

Bob 

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<DIV>In the same vein, 
how does applying tile to a cob wall work?  I mean, say I wanted to put up 
tiles in a bathing area, wouldn't putting up glazed tiles with mortar seal the 
wall, and wouldn't that be bad?  Or could you just embed the tiles in the 
cob?  I also had a friend who was thinking of using tile to mosaic the 
outside of a cob building...  Would this cause breathing 
problems?</DIV>
<BLOCKQUOTE>
 <DIV align=left class=OutlookMessageHeader dir=ltr>-----Original Message----- From: Bob 
 [mailto:owl at steadi.org] Sent: Friday, May 12, 2000 11:57 
 PM To: coblist at deatech.com Subject: Cob: breathing cob 
 walls </DIV>I'm glad someone brought up the need for cob walls 
 to breathe.  In New Mexico the restorers had the bright idea of coating 
 the outside of a very old adobe church with mortar to protect it from the 
 weather etc.  It almost destroyed it, however.  Moisture that is in 
 most all air entered the wall from the inside and got trapped just under the 
 mortar. Over the years it softened the clay in the raw (unfired)  
 bricks.  Watertight sealants will gradually soften the clay under 
 them.  It may not show in a year but it will over time.  This 
 church was in a quite dry climate near Santa Fe, New Mexico.  If you 
 would like more details I will look up the recent Smithsonian article and put 
 the page and issue on this net.   IT IS DANGEROUS TO TRY TO SEAL AN 
 ADOBE OR COB WALL.  THEY NEED TO BREATHE. Potassium silicate, I 
 believe is a sealants that can cause this gradual deterioration of unfired 
 clay walls.    You may be undermining your building.  Just 
 what potassium silicate would do to garden walls is another question.  
 Perhaps they would make the wall last longer than an unprotected  rain 
 drenched wall.  Much better are the ideas of putting a roof on the wall 
 with an overhang and putting stones in it that stick out.  Even 
 terracotta (cooked earth) tiles that are not glazed, just low fired, would be 
 good protection even though they are a little porous.  Most of the rain 
 would run off.  If the wall breathed the little moisture that went 
 through into the wall would likely work its way to the sides and 
 evaporate. What is important to remember is that even inanimate things 
 are dynamic, changing slowly or fast depending on the climate.  In the 
 Egyptian desert they can last for thousands of years but there are few 
 places  that dry in the world.  Even the ancient hieroglyphics 
 thousands of years old, when inclosed and viewed by too many  tourists 
 can be destroyed by the moisture evaporating from their bodies.  So we 
 have to bend with the weather and the impacts of changing climates and 
 recognize that every move we make impacts the world of future 
 generations.  Acid rain, thanks to our  blind use of technology, is 
 decaying even stone monuments that lasted thousands of years.  The 
 automobiles in Athens are destroying the ancient Athenian buildings, for 
 example. Americans look for quick fixes.  When they are efforts to 
 short cut natural processes they always backfire.  Cob is great because 
 it is mostly a product of nature and when properly used and cared for can last 
 for ages.  Tune into it and it will give you a singing house.  Try 
 to defeat the natural process and they will let you down, or let the roof down 
 on your heads. Bob </BLOCKQUOTE></BODY></HTML>