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Re: [Strawbale] prefab strawbale
On Sat, 12 Sep 2009, in GSBN Digest, Vol 17, Issue 4
Derek Roff <derek@unm...> wrote:
[ <snipped> for the sake of brevity, see end-note ]
I am very interested in strawbale panels, and in finding ways to increase
the use of bales in all kinds of construction.
I agree ... that we will need to find more
industrial bale building methods, if we are to interest certain
segments of the building industry.
Finally! I get to disagree with the Derelict.
To be perfectly frank (and at the risk of getting the Straw Wolf very PO'd
at me), the notion of pre-fab straw bale panels elicits in me, a reaction
not unlike that when I first saw bits of lettuce and other miscellaneous
vegetable parts in hermetically-sealed, tarted-up plastic bags being sold
as the raw materials for salads in supermarkets, presumably intended for
the harried cook who is either too time-challenged and/or too
hand-eye-co-ordination-challenged to break up the lettuce on their own.
In other words, a reaction of puzzlement and incredulity tinged with a bit
of disgust (at the level of sloth that would be associated with the use of
such a "product").
I don't think that the answer (or even _a_ way) to increase the use of
straw "in all kinds of construction" is to make the basic module even more
cumbersome and difficult to handle by putting a bunch into a pre-assembled
panel that needs machinery just to move it.
Furthermore, bales pre-assembled into large panels tends to push
owner/builders out of the building process whereas the process of stacking
individual bales to make walls is such an intuitive thing that people who
would otherwise find the spectre of building their own home intimidating,
are less so.
And the idea of pre-fabricating pre-plastered straw bale panels has the
same problems as the naked straw bale panels, but multiplied by a factor
of #X and with the addition of the potential for serious moisture-related
problems even before the panel has left the fabrication site and
moisture-related problems after erection at the site due to inherent
shortcomings in "the system" with regards to proper flashing and
air-sealing details.
The pre-plastered panels also pretty much preclude any possibility of
utilising the mesh for pre or post-tensioning to provide the wall sections
with lateral resistance to live loading, the most effective/efficient
means of providing that resistance.
And the list of "cons" doesn't end there. Fact is, I'm hard-pressed to
come up with any points about pre-fab SB panels that improve SB walls for
a homeowner.
Pre-fabricating SB panels off-site doesn't make much sense from a
viewpoint of basic economic$$ either.
It's akin to a bicycle tube manufacturer in Asia shipping their product to
North America fully-inflated.
Stacking bales up to make walls is not such an onerous task that it needs
to be pre-done for people. Neithter is making up a frame to surround a few
bales to create a "panel".
The difficult part of making a SB wall is the plastering so rather than
ship the entire wall section with straw, it would seem to make more sense
to simply pre-fabricate pre-cast rainscreen panels and let the builder get
their own straw locally, straight from the grower.
If the straw is going to be made a proprietary component, then rather than
simply stacking up run-of-the-mill bales to make those panels, some
thought and effort might go into taking the straw from jumbo bales or
round bales (the growers preferred unit, production of small rectangular
bales being a labour-intensive process (read: Major PITA) for which it is
increasingly difficult to find the necessary labour) ... to make a
continuous straw core that is unbroken by joints and can be varied in
thickness (and hence R-value) to suit a particular job specification.
And ideally, this process would be one that is portable so that the entire
wall length could be cast on-site/in-situ as a tilt-up panel. As to how
the trapped moisture problem would be solved, that is something for the
proprietors of the proprietary process to figure out.
But the best direction I think, is not the "panel" approach.
I think that a better "bale" is the way to go.
Rather than trying to utilise a basic module that is essentially a
handy-sized package of toilet tissue for livestock, a stackable,
_building_ module where the straw of a known density/moisture content is
encapsulated with an effective air/fire/insect/rodent barrier into a
reliably consistent unit that can be managed by one person using only
their hands and stacked like unit masonry or insulated concrete forms to
make a wall, would be a Good Thing that would have a better chance of
being gobbled up by "the building industry".
{For those not on the GSBN List who would like to see the original context
of this discussion, please visit the accessible-to-the-public GSBN archive
on somewhere on YahooGroups. You'll have to pester Wild Bill-bob
Christensen for the location of those archives 'cuz Man, I really don't
know where the heck they are.)
--
=== * ===
Rob Tom
Kanata, Ontario, Canada
< A r c h i L o g i c at ChaffY a h o o dot C a >
(manually winnow the chaff from my edress in your reply)
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