[GSBN] prefab strawbale

[cmagwood at kos.net]

> 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.

Well, as somebody who is committed to both owner-built SB
and pre-fab, I'd like to suggest that the two are not
mutually exclusive. In fact, they can exist in perfect
peace and harmony! My reasons for such belief follow...

> 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.

Some people find stacking their own bales the perfect
solution. Others actually do find the idea quite
intimidating and typically choose between doing their own
SB or hiring a non-SB contractor to build them a stick
house. Prefab doesn't stop the owner builder, but it sure
encourages the other type to choose SB.

> 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.

I would have to heartily disagree with this. I've seen
enough shoddily sealed and flashed owner-built (and
contractor built!) SB to know that the way we are doing
the panels (with built in wall base flashing and vapour
barrier details at all seams) results in a very tight
building envelope that is the equal to the best built site
SB homes and far better than most.

> 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.

There has surely been enough testing of load-bearing
panels now to know what's necessary in the way of mesh.
Our Ontario engineers have been very comfortable with us
building site-made SB meshless for years. True, this isn't
adequate for California, but looking at the earthquake
results for the Pakistan project gives us some clue that
super-pretensioned mesh is not the only way to make strong
walls for earthquake zones. There is no reason that panels
can't be made with mesh... they can be made to equal their
site-built counterparts for whatever circumstances they
need to meet.

> 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.

I can! Cost, for one. Our panelized building this year
took unskilled student labour and turned out perfectly
plastered, flashed and VB'ed walls in one quarter of the
time it would have taken to site build. More reasons: The
plaster is not relying on two or three coats and the
sometimes questionable bond between them, there were no
weather issues, tarping, bad plaster curing due to sun,
wind, rain, hot, cold, etc. The walls are straight and
true (for those many, many people who like'em that way for
some reason!). The owner didn't have to have bales, sand
and binder delivered to site, tarped, covered, etc, and
then deal with the on-site mess of plastering. The plaster
is of an even thickness, with no questionable spots where
bale bulges thin things out. I could go on...

> Pre-fabricating SB panels off-site doesn't make much sense
> from a
> viewpoint of basic economic$$ either.

Yes, it does. It means a bale wall can be had for less
cost than a frame wall, and it can be had by owner
builders, contractors and even evil developers, and the
advantages of bale walls can be enjoyed by more people.
Site built SB for the owner builder can deliver this too,
but often it's not the case. There are more than enough
cases of owner-built SB going over the costs of
conventional building. Prefab guarantees against this (at
least for the wall portion of the build!).

> It's akin to a bicycle tube manufacturer in Asia shipping
> their product to
> North America fully-inflated.

I would say that unless an owner builder is carrying the
straw bales, sand and plaster binder to his/her site by
bicycle, donkey, hand-cart or other carbon neutral
delivery system (put up your hands if you've done this!),
then there's not much difference between having all the
individual components of a wall brought to site by a
machine, or having the assembled components arrive by
machine. The prefab system we're working on can be set up
in micro-"factories" close to building sites. Our panels
this year stopped the ingredients on their way to the
building site, assembled them and then delivered the
finished product to the site, saving all three deliveries
from going as far.

> 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".

Our system uses no more wood than the best load-bearing
design, and in fact less than most. It is identical to a
low wood usage, load-bearing wall. Owner builders who want
to stack their own bales can still do so. But how many who
stack'em still hire out the plastering? That's the onerous
part, and lots of dedicated owner-builders hire people
with machines to do this work for them (at great cost).

> 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.

Sorry, but this makes no sense to me. How does the
rain-screen bond to the straw? Wasn't this tried to
disastrous effect by those guys in Minnesota? We know that
plaster-on-straw walls work, and these prefab panels
create THE SAME plaster-on-straw system. Can it be
susceptible to moisture? Yup, just like SB. Can it be made
to meet that challenge and work in the real world. Just
ask the few thousand SB home owners whose houses haven't
rotted.

> If the straw is going to be made a proprietary component,

There's NO talk of proprietary in our efforts. In fact,
I'm spending all kinds of time showing people how to do
this for themselves (including owner builders who would
make their own panels). The system is free for the taking,
and we continuously and publicly discuss it and talk about
what's worked and what hasn't, just like with site-built.

> As to how
> the trapped moisture problem would be solved, that is
> something for the
> proprietors of the proprietary process to figure out.

Well, I'm not a proprietor but I don't know what trapped
moisture problem you are talking about. We start with
bales that are as dry as usual, and apply a plaster with
the same amount of water in it, and give the walls the
same amount of exposure to the outdoors (minus a couple
days in the form... not sp different, I would think, to
having a building tarped (except for less time). We use
plasters with the same ability to transpire that moisture,
so what moisture is being trapped that isn't being trapped
on-site? I keep coming to the same point: these are the
exact same walls we've always been building, all we do is
plaster them lying down in a different place.
>
> But the best direction I think, is not the "panel"
> approach.
> I think that a better "bale" is the way to go.

And, of course, there is room for this kind of development
too. But will the better bale use machines to make it? I
think so. And in making that "better bale" as you
describe, will hiccups be encountered? Will moisture
concerns exist? Will having super bales made in Wyoming
and distributed via Home Depot be the solution?

The beauty, to me, of our prefab system is that it stays
small, local, close to the production of the resources,
costs nothing to set up as a factory, is not proprietary,
can be adapted to many styles of wall and building... hey,
a lot like SB!

What do I love about SB? I love the fact that all kinds of
approaches get tried, discussed and developed. I would
never promote prefab as the only way to go. If I did, I'd
stop making the hand-crafted, site-built SB buildings I
make and start a factory. I love site built SB. But I can
see its limitations and I happen to think that the prefab
system we've worked out eliminates those limitations. It's
not for everybody, of course, but it could be for a lot of
people.

Thanks for the space to discuss this!

Chris