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Re: GSBN:Re: fire test -- your opinions?



Rob,

Though I largely agree with what you are saying (especially the part
about the high impacts of portland cement and lime) it is also the case
that for those of us down south those other tests, as far as the
insurance and code folks are concerned, don't really exist because they
aren't in full compliance with everything they think makes them valid.
If we were sure that the earthen plastered wall would pass the hose
stream test I think we'd be much more ready to jump on that bandwagon,
and take that gamble, though I've been a strong proponent of earthen
plasters for many years.

So, I wonder if anyone knows of successful fire tests of bales with
earthen plaster? If so were they for a similar time period and did
these other tests have requirements similar to the E-119 hose stream
test? There's a lot at stake and we're not discounting the importance
of the issue of trying to reduce the ecological footprint of these
structures. We're also trying to make sure we end up with something
that will truly serve the evolution of bale construction once we've
spent this considerable chunk of money on these tests. Worst case
scenario may be that we test two wall panels and neither passes.
Obviously getting something to pass that is not what people want or
should be building is as bad and maybe worse. But we need this to be
result in progress for the acceptance of bale walls.

Let's keep talking about it...

David

-----Original Message-----
From: Rob Tom archilogic@...
To: GSBN GSBN@...
Cc: ecobruce@...
Sent: Wed, 26 Apr 2006 17:41:12 -0400
Subject: GSBN:Re: fire test -- your opinions?

 Bruce, King of Sausalito wrote:

> ASTM fire test ... the tentative wall types are two-string Texas
> wheat bales---one with bales flat, and one with bales on edge---both
 > with no pins or mesh, and both with two coats of lime-cement
plaster.

 > the people who will need a fire rating for their building (I
suspect)
> will also need the higher hardness and durability of lime-cement.
>
> Any comments?

Given that we already we already have data for the fire-resistive
performance of Portland cement lime plasters when used to encapsulate
straw bales and that there are already data and standards in existence
 which clearly define the cover requirements and what performance can
be
 expected of such plasters when used in non-SBC scenarios, it seems
doubly
 redundant to expend scarce research & testing resources to test
identical
PC/lime plasters on almost identical substrates (albeit oriented
differently).

 Granted, one would expect the strings to fail relatively quickly on
the
on-edge stacked bales (elapsed time quite likely predictable based on
 existing test data) but one would hope that anyone building with
on-edge
stacked bales would know that through-the-wall ties would be needed to
 make up for the poorer straw/plaster bond anyway so that string
failure
due to edge-stacking should not be an issue.

 It could be easily argued that the biggest Brown mark against SBC is
the
 high embodied-energy content of the cement and/or lime that is used in
the
 "typical" SBH, (ie slab-on grade foundation, PC and/or lime plaster
skins
inside and out).

 If the only officially-recognised fire test data "out there" is data
for
PC/lime plasters then those will likely be the only plaster types that
 will be recognised by the officials who decide upon what gets written
into
the Codes or gets built in their jurisdictions for a long, long time.
(Remember the rebar pins requirement ?)

In most parts of the world outside of Krazy Kalifohnia (where the
 landscape spontaneously self-combusts on a regular basis) fires begin
on
the interiors of buildings and it is the fire resistance of interior
materials that are of primary concern.

There is really no reason why we should not be promoting the use of
earthen plasters on interiors since its weakness (poor weathering
resistance) is not an issue on interiors.

 There is no doubt in my mind nor should there be in that of any
building
 or fire official that 40mm or more thickness of a Portland cement or
lime
 plaster is at least as fire resistive as any of the conventional
cladding
 materials that are routinely used in urban housing situations --
vinyl,
 wood or aluminum siding, synthetic stucco-covered polystyrene foam
boards
etc.

 Nor is there any doubt in my mind that Portland cement/lime plasters
do
 not provide sufficient protection against rain wetting of SB walls if
the
plaster is fully exposed.

 If SBC were to gain widespread use in urban scenarios, I doubt very
much
that the tight confines of urban and suburban lots would allow for the
 widespread use of wrap-around porches and sufficiently wide overhangs
that
would be required to provide adequate protection for fully exposed
plasters.

So that tells me rainscreen claddings will likely be the cladding of
necessity in urban situations and since bales need to be fully
 encapsulated by plaster, even beneath rainscreen claddings, do we
really
 want to be creating a scenario where future SBH builders will be
required
 to use PC/lime plasters under those rainscreens even though the
weather
 resistance/hardness/durability aren't really required and where
earthen
plasters (albeit slightly thicker to make up for lower strength) would
serve quite nicely ?

 I say if only two walls can be tested, test one with PC/lime plaster
on
 on-edge bales if you absolutely must test a PC/lime plaster, but the
other
one absitively & posolutely should be an earthen mix, preferably a mix
that is *the* best in the SB World so that the numbers that do result,
will amaze the pants off of the officials.

=== * ===
Rob Tom
Kanata, Ontario, Canada
<ArchiLogic at chaffyahoo dot ca>
(winnow the chaff from my edress in your reply)

Please visit <a  target="_blank" href="http://www.mercycorps.org/";>http://www.mercycorps.org/</a>

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