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Re: GSBN:fire test -- your opinions?



I also agree w/ Dan and John. While I'm hopeful that both walls will
pass in whatever configuration they are built in, I think that wire mesh
will only help make the wall stronger (especially w/ cement in the mix),
and feel that it's worh it to hedge our bets -since we have the opportunity.

BTW I'm assuming that when we say mesh, we are talking about  the
product called "chicken wire" in my part of the world.

Ben Obregon

Dan Smith wrote:

I agree with John, that at least one of the tests should be cement or
(cement-lime) plaster with mesh, as this would allow the best option of
getting a 2 hour rating, if that's possible in this test.

Dan Smith

-----Original Message-----
From: GSBN [<a  target="_blank" href="mailto:GSBN@...";>mailto:GSBN@...] On Behalf Of John
Swearingen
Sent: Wednesday, April 26, 2006 10:32 AM
To: 'GSBN'
Subject: RE: GSBN:fire test -- your opinions?

I agree with Bill that I wouldn't expect much performance difference
between
flat and edgy bales as far as heat transmission goes--wouldn't that
closely
correspond to the R-value, which is similar.

So the only reason for testing bales on edge would be to see if the
strings
would pop, and we know that with some certainty.  What we don't know is
what
will happen after they pop, in a situation where the plaster is
compromised.
Once a bale even begins to disgorge, the conflagration spreads like
wildflowers in a prairie. In an assembly using mesh, disgorgement would
be
prevented as long as the mesh holds. (Obviously metal mesh has an
advantage
over plastic or natural fiber here).

Marty mentioned that in the dark of the night he's worried that a
plaster
failure would allow disgorgement and this could lead to a failure of the
entire assembly which would result in frowns on the faces of inspectors
and
could ruin the value of the test for just about everybody.   He might be
right, and so I'd suggest doing a test with some kind of standard metal
mesh.or doing the first test w/o mesh, and if the scenario above occurs,
use
mesh for the second test.

Of all the performance variables that could be tested--such as plaster,
mesh, orientation--the one that I would predict would give the greatest
difference, potentially, would be mesh, followed by earth plaster.

John "My Strings are Melting" Swearingen

John Swearingen
SKILLFUL MEANS
design and construction
HYPERLINK "www.skillful-means.com"www.skillful-means.com


-----Original Message-----
From: GSBN [HYPERLINK
"<a  target="_blank" href="mailto:GSBN@..."mailto:GSBN@...";>mailto:GSBN@..."mailto:GSBN@...]
On
Behalf Of billc_lists@...
Sent: Wednesday, April 26, 2006 12:57 AM
To: GSBN
Subject: Re: GSBN:fire test -- your opinions?


Hi all,

Interesting points re: edge vs flat, cement vs cement-lime vs lime vs
earthen plasters.

I think it's clear that order to really get the full data, more than two
tests will need to be done. Typically in a scientific procedure you'd
change
just one variable at a time, for instance bales on edge vs bales flat,
with
all other variables (plaster, etc) remaining the same. Then you'd vary
another constraint, such as the plaster types, so that if you'd already
done
edge vs flat with one type of render you'd be able to predict how the
performance would vary (or not) using different plasters as a result of
bale
orientation.  Otherwise you have trouble saying exactly what caused any
difference you may have observed.

I personally don't think that we'll see a huge difference between edge
vs
flat, though I can certainly see the reasoning behind doing such tests
to be
sure.  I don't think molten strings are going to make much difference,
especially in a test wall which is built within a four sided frame -
it's
not likely that the straw is going to go anywhere. The question is more
a
matter of how heat is transferred through the bale - do the hollow
straws
allow it to move faster through flat bales?  Do vertical straws cause
heat
to move to the top more quickly, causing failure there?


Regarding plasters, curiosity got the best of me and I pulled some
numbers
from the SB Registry to see just what people are using on their walls.
For
exterior walls, they can choose from:

cement plaster
earth or clay plaster
lime plaster
wood siding over plastered bales
wood siding over unplastered bales
other - Describe if other

or any combination of the above.  Of those who reported their exterior
finish, the resulting numbers are:

Exteriors:

Cement only: 235

Earth only: 72

Earth/lime: 34

Lime only: 51

with a scattering of other strange combinations (perhaps different
treatments for different walls).  For interior walls, they can choose
from:

cement plaster
earth or clay plaster
lime plaster
gypsum plaster
wood
sheetrock
other - Describe if other

or any combination.  The resulting numbers are:


Interiors:

Cement only: 116

Cement plus other: 39 (includes cement &amp; gypsum, cement &amp; sheetrock,
cement
&amp; wood, etc)

Earth only: 94

Earth &amp; Gypsum: 13

Earth &amp; lime: 13

earth &amp; other: 15

and again, a few who did other, more bizarre combinations.


So though these numbers are by no means definitive, it looks to me that
cement beats earth for exteriors in general by about 2 to 1, but they're
pretty close to an even match for interiors.

Which then begs the question:  Are we testing for fire resistance of
interior walls or exterior, or both?

On the flat vs edge orientation, I see 316 flat vs 84 on edge.

I don't know if those numbers will help anyone make a decision, but I
figured I'd throw them out there.  There's more reported use of earth
plaster than I expected there to be.


--
Bill Christensen
<HYPERLINK
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GSBN is an invitation-only forum of key individuals and representatives
of regional straw construction organizations. The costs of operating
this list are underwritten by The Last Straw Journal in exchange for use
of the GSBN as an advisory board and technical editing arm.

For instructions on joining, leaving, or otherwise using the GSBN list,
send email to GSBN@...HELP in the SUBJECT line.

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----
GSBN is an invitation-only forum of key individuals and representatives of regional straw construction organizations. The costs of operating this list are underwritten by The Last Straw Journal in exchange for use of the GSBN as an advisory board and technical editing arm.

For instructions on joining, leaving, or otherwise using the GSBN list, send email to GSBN@...HELP in the SUBJECT line.
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