[GSBN] Fwd: Humidity within a bale house....

[ejgeorge at riseup.net]

Ironically, two messages just came through on the NBNE list regarding  
a strawbale root cellar and a straw bale walkin cooler with similar  
humidity concerns -- I've added them below if anyone wants to comment...

ej

ej George
Certified Sustainable Building Consultant
607-387-3602
ejgeorge at riseup.net


Quoting "Rikki Nitzkin" <rikkinitzkin at earthlink.net>:
>>
>> I have recently gotten an email from a man who wants to build a SB   
>> mushroom farm. He would like to know if it is a problem that the   
>> INTERIOR of the building has a humidity level of 75-90%.
>>
>> I usually prefer to use breathable earth plasters (or lime), but I   
>> am wondering if this would be a good case to apply a WATERPROOF   
>> (cement? latex paint?) plaster to the interior of the building to   
>> avoid excess humidity in the walls.
>>
>> Any thoughts/suggestions?
>>
>> Rikki Jennifer Nitzkin
>> Coordinadora de la Red de Construcción con Balas de Paja
>> www.casasdepaja.org
>> casasdepaja at yahoo.es
>> http://casasdepaja.blogspot.com/
>>
>>

Straw Bale Root Cellar...Yea, sounds crazy no?

My client wants to spare the cost of building an underground bunker  
for a root cellar. I proposed to incorporate one in the straw bale  
?connector? between the old bale home and the new bale home (this is  
the Earth Sweet Home Institute in Dumerston, VT). I generally  
understand the basic principles of a root cellar; temp, humidity, air.  
To spare you all the details of the design my main concern is the  
desired level of humidity. Two of the four walls of this above ground  
root cellar are straw bale and of the two, only one, (the longest), is  
exposed to the outside. The other two including the ceiling are  
conventionally framed with cellulose or rigid with an AB. What have  
people used to make the interior plaster have close to a 0 perm  
rating? And is this just a crazy idea of mine?

andy mueller
greenspace colllaborative
www.greenspacecollaborative.com

hmm...

my root cellar is in my basement.  two walls are basement foundation  
walls, without damp-proofing or insulation.  the floor has no slab,  
just gravel and footer drains.  the other two walls are stud framed;  
they and the ceiling are insulated with batts and sheetrocked.  I  
applied a two-coat epoxy paint to the rock to make a vapor-impermeable  
and scrub-able surface.  The interior humidity should be in the 90%  
range, optimally; given that relative atmospheric humidity in the  
winter is very low, ventilating this air makes for drier than ideal  
conditions requiring regular misting and spraying of the room.  This  
is where both the diesel wall surface and the drain floor come in  
really handy.  Also, things do get very funky in there, so being able  
to wash the walls down in h2o2 or other disinfectant is important.

If you wanted to trick out the interior plaster to be waterproof, I  
suppose you could just go ahead and apply a similar strong paint to  
the surface; I wouldn't bother with anything that couldn't receive a  
good vigorous wipe-down, and I'd aim on getting the surface as smooth  
as practically possible.

I hope this helps...good luck and keep us posted!

Deva


From: Jacob Deva Racusin <buildnatural at googlemail.com>
Subject: [nbne] straw bale cooler
To: nbne at lists.riseup.net
Date: Monday, April 6, 2009, 1:38 PM

Alright, Andy, I'll see your root cellar and raise you a produce cooler...

I just spoke with a client who runs a farm with his wife, and they want to
build an insulated cooler to store their produce after harvest during the
summer.  They would like to use straw as an ecologically-friendly insulation
material.  They will be putting up the walls within the envelope of an  
existing
barn; they would remove the siding from the walls where the bales would be
located, build internal-wrap bale walls (barn framing to the exterior,  
plaster,
and re-side.  Commercial air conditioner will control interior climate.

Am I missing something in thinking that straw with good plastering  
interior and
out will be able to handle this situation?  We're looking at 80-90 degF and
high humidity (70-100%?) outside in the summer, and 35-40 degF and much lower
humidity inside.  Of course condensation inside could be an issue, but the
plaster should be able to control that I would think/hope, if the  
space is kept
ventilated (which it will with powered air conditioner).  Bigger concern I
suppose is condensation in the wall, which seemingly would be most  
likely close
to the interior, thus a very well-detailed exterior plaster coat will be key.
This won't have the same pressures of high interior humidity (and
associated decomposition) as the root cellar, although cleaning will  
still be an
issue to some degree...

Am I being too risky in recommending bales, or does this seem reasonable?  It
kinda seems like baling in the southeast, only a bit more extreme...I  
appreciate
any feedback or resources.  Anyone know of any precedence?

Best,
Deva