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Re: GSBN:Re: fire test -- your opinions?
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...
From: Rob Tom archilogic@...
To: GSBN GSBN@...
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
> the people who will need a fire rating for their building (I
> 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
expected of such plasters when used in non-SBC scenarios, it seems
redundant to expend scarce research & testing resources to test
PC/lime plasters on almost identical substrates (albeit oriented
Granted, one would expect the strings to fail relatively quickly on
on-edge stacked bales (elapsed time quite likely predictable based on
existing test data) but one would hope that anyone building with
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
due to edge-stacking should not be an issue.
It could be easily argued that the biggest Brown mark against SBC is
high embodied-energy content of the cement and/or lime that is used in
"typical" SBH, (ie slab-on grade foundation, PC and/or lime plaster
inside and out).
If the only officially-recognised fire test data "out there" is data
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
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
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
or fire official that 40mm or more thickness of a Portland cement or
plaster is at least as fire resistive as any of the conventional
materials that are routinely used in urban housing situations --
wood or aluminum siding, synthetic stucco-covered polystyrene foam
Nor is there any doubt in my mind that Portland cement/lime plasters
not provide sufficient protection against rain wetting of SB walls if
plaster is fully exposed.
If SBC were to gain widespread use in urban scenarios, I doubt very
that the tight confines of urban and suburban lots would allow for the
widespread use of wrap-around porches and sufficiently wide overhangs
would be required to provide adequate protection for fully exposed
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
want to be creating a scenario where future SBH builders will be
to use PC/lime plasters under those rainscreens even though the
resistance/hardness/durability aren't really required and where
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-edge bales if you absolutely must test a PC/lime plaster, but the
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.
=== * ===
Kanata, Ontario, Canada
<ArchiLogic at chaffyahoo dot ca>
(winnow the chaff from my edress in your reply)
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