[Strawbale] Bales on edge and insulated structures

Derek Roff derek at unm...
Wed Oct 13 15:43:14 CEST 2010

Hi, Rikki,

It sounds like you've got a system that is working well for you, and 
that is great.  My view is that most building decisions have pluses 
and minuses.  The pluses are the reason that we pick a system, and 
the minuses have to be dealt with.  Usually, they can be, if we want 
to make the effort.

You ask what are the disadvantages of your three sided column 
approach.  One is that a three sided box column will be substantially 
less strong than a four sided one.  The fourth side makes a large 
difference in the weight the column can support, and the out of plane 
loads that it can resist.  I'm not saying that you shouldn't build 
this way.  Just that when a builder removes strength from one element 
in a building, she/he will have to be sure that sufficient strength 
remains, or add strength via other building elements.

If I'm visualizing correctly, I would say another disadvantage is 
that this kind of column interrupts the running bond stacking of the 
bales.  This makes the wall less stable, and less able to resist out 
of plane loads.  It means another interface between dissimilar 
materials, which can lead to air infiltration and plaster cracking. 
Again, these issues can be dealt with, if one chooses.

Best wishes,

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...

--On Wednesday, October 13, 2010 1:20 PM +0200 Rikki Nitzkin 
<rikkinitzkin at earthlink...> wrote:

> After listening to this last debate, I have a doubt...
> I have built very few wooden structures for straw (mostly I use
> loadbearing), but when I do, I have always found that using Box
> Beams   (like the ones used for loadbearing roof-plates) vertically
> as a   structure work very easily. In the case of using them as
> posts I only   cover one side with OSB (9mm), not both, to save on
> material. They are   easy to make, insulate, fix to the base plate,
> and permit you to top   the structure off with a beam (probably
> another box beam) centered   over the bales- which makes it easy to
> compress the bales within the   structure (with car jacks or truck
> straps). This makes a very solid,   straight wall with an insulated
> structure and permits using on-edge   bales.
> When I do this (so far only with small "demonstration" buildings)
> it   works well. I usually put the box beam posts in the corners,
> and   around windows, and if there where a longer wall with no
> openings   (never happened so far) I would put more posts in- with
> a maximum of   2,5 meters between posts (which is the length of the
> OSB).
> What are the disadvantages of doing this? I see only advantages...
> except (if using on-edge bales) that the first layer of plaster is
> a   bit more difficult to apply.
> If there are no disadvantages, why don't people use this sistem
> very   often?
> take care,
> Rikki

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