[GSBN] Use of and protection - steel columns in bale walls

[Derek Roff]

I've seen a black mold layer on the straw around the steel in several 
walls that I have helped dismantle.  My experience is in the 
southwest US, so the examples are in fairly dry, fairly warm 
locations.  I haven't dismantled that many walls, so the fact that I 
have seen this several times causes me some concern.  On the other 
hand, the mold layer is very thin- a millimeter or less.  While I 
didn't do microscopic analysis, I looked carefully at the nature and 
distribution of the black material, and I am convinced that what I 
saw was mold, and not simply discoloration.

The mold that I have seen in this context is superficial, and 
wouldn't cause any structural concerns.  On the other hand, I want SB 
houses to last for many decades, not just the few years that these 
walls had been in existence.  What would happen to this mold over a 
longer time span?  My guess is "not much," but I could be wrong. 
Overall, it decreases my enthusiasm for steel in contact with straw.

Derek "too many hands" Roff


--On Tuesday, June 16, 2009 7:44 PM -0700 John Swearingen 
<jswearingen at skillful-means.com> wrote:

> We've only had problems a couple of times, on sides exposed to very
> hot sunlight, and rather thick steel.
>
> I don't think condensation presents a significant risk, as the
> steel's temperature will be very close to the temperature of the
> surrounding straw.  My notion is that condensation will not occur
> at a theoretical dew point location in the wall, but will happen on
> the back side of the exterior plaster.
>
> John "Dewey Eye" Swearingen
>
>
> On Tue, Jun 16, 2009 at 6:27 PM, John Glassford
> <jacksflat at gmail.com> wrote:
>
> G ' day
>
> We have used steel a few times and the oldest now was built in
> 1998.  This one did not have any protection.   We set the steel
> columns to the inside of the bales.  No problems
>
> With other steel posts we have painted them with a bitumen based
> tar paint these posts were to the outside and the inside:
>
> http://glassford.com.au/main/?page_id=1364
>
> We did the ame with the Hall in Sydney no problems to date.
>
> We try to avoid steel where possible but in big buildings steel is
> the only way to make solid window and door frames.  This building
> below is load bearing jumbo bales with steel window and door frames:
>
> http://glassford.com.au/main/?page_id=773
>
> Kind regards
> John Glassford
> Huff 'n' Puff Constructions
> http://www.glassford.com.au
> 61 2 6927 6027
> In Australia (02) 6927 6027
>
> The Orphan Rescue Kit Africa
> http://theork.com
>
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> http://www.mountainsofthemoon.org
>
>
>
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>
> --
> John Swearingen
>
> Skillful Means
> www.skillful-means.com
> blog: https://skillfulmeansdesign.wordpress.com



Derek Roff
Language Learning Center
Ortega Hall 129, MSC03-2100
University of New Mexico
Albuquerque, NM 87131-0001
505/277-7368, fax 505/277-3885
Internet: derek at unm.edu